King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

Mihailo Stjepanovic; Violeta Mihailovic-Vucinic; Branislav S Gvozdenovic; Jelena Milin-Lazovic; Slobodan Belic; Natasa Djurdjevic; Nikola Maric; Aleksa Golubovic

doi:10.1371/journal.pone.0273126

. 2023 Sep 5;18(9):e0273126. doi: 10.1371/journal.pone.0273126

King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

Mihailo Stjepanovic ^1,^2,^*, Violeta Mihailovic-Vucinic ², Branislav S Gvozdenovic ³, Jelena Milin-Lazovic ⁴, Slobodan Belic ¹, Natasa Djurdjevic ¹, Nikola Maric ¹, Aleksa Golubovic ¹

Editor: Gernot Zissel⁵

PMCID: PMC10479938 PMID: 37669301

Abstract

Introduction

Sarcoidosis is a multiorgan, multisystem chronic disease of unknown etiology and unpredictable course. Health status is reduced in sarcoidosis and assessing it is a difficult multitask effort due to many faces this disease might have. Recently, a new questionnaire for assessing health status in sarcoidosis was developed by a group of authors from England–King’s Sarcoidosis Questionnaire (KSQ). The benefit of KSQ is the ability to develop the best care plan for the patient, as well as to differentiate the efficacy of the administered treatment.

Objective

The aim of this study was to validate the KSQ in Serbian speaking population of sarcoidosis patients. The test itself is a modular, multi-organ health status measure for patients with sarcoidosis for use in clinic and the evaluation of therapies. The correlation of KSQ with different clinical course of sarcoidosis (acute vs chronic disease) and with the clinical outcome status (COS) in sarcoidosis was also investigated.

Methods

A total of 159 biopsy positive sarcoidosis patients participated in this study. The average age of the participants was 49.67, majority was female (67.3%) and majority had only pulmonary form of sarcoidosis (71.7%). KSQ ‐ new disease-specific health status instrument, was compared with 5 other already existing instruments already used and validated in sarcoidosis (Saint George Respiratory Questionnaire- SGRQ, Daily Activity List -DAL, Fatigue Assessment Scale- FAS, Medical Research Council dyspnea scale–MRC, Borg Dyspnea Scale and 15D as general questionnaire.

Results

KSQ has significant correlation with other quality of life questionnaires already used in sarcoidosis. Translated version of KSQ shows significant internal reliability, similar to the original KSQ. Serbian version of KSQ has significant correlation with different clinical course of sarcoidosis and with COS as well. The translated version of KSQ is reliable sarcoidosis specific instrument for assessing health status in these patients.

Introduction

Sarcoidosis is a multisystemic inflammatory disease of unknown origin, in which non-caseous granuloma present in different organs leads to decrease of function. Depending on the localization and extensivity of granuloma, sarcoidosis can present with a wide variety of signs and symptoms [1].

The most commonly afflicted organ in sarcoidosis are lungs and mediastinal lymph nodes, therefore, performing pulmonary function tests (PFTs) and chest X ray are essential in both diagnostics and follow-ups. Being easily performed and replicated, both procedures can help the physician evaluate the activity and severity of the disease [2]. It should be noted that the clinical presentation of sarcoidosis is not specific, and chief complaints in patients are fatigue, chest pain, cough, dyspnea, fever and swelling of joints. The presentation is further complicated when taking into consideration the chronic and extrapulmonary forms of disease. The available tests and the severity of symptoms have not shown correlation, which has caused a certain division between physicians and patients regarding the intensity of presented symptoms [3]. One of the most commonly presented symptoms in patients with sarcoidosis is fatigue, which is completely subjective parameter, and, if left untreated, can lead to significant cognitive impairment [4, 5].

As sarcoidosis most commonly afflicts the working age population, any prolonged activity of the disease and its symptoms leads to significant decrease of quality of life, which leads to further deterioration of the state of the individual. Previous studies have tried to find a correlation between the intensity of symptoms and the prognosis of the disease [6, 7], however, no precise algorithm could be developed. It should be noted that patients with no symptoms at the moment of diagnostics have better clinical outcome, compared to patients with any clinical presentation.

The relationship between heath status and sarcoidosis was first examined in 1997 [8]. Since that time until now authors have been trying to find out the best measure considering patients quality of life and/or health status [9].

The need for a quality-of-life questionnaire specific for sarcoidosis has led to the development of King’s Sarcoidosis Questionnaire (KSQ) [10]. KSQ is a modular multi-organ health status measure for patients with sarcoidosis for use in clinic and the evaluation of therapies. It consists of five modules: General health status-GHS (10 items), Lung (6 items), Medication (3 items), Skin (3 items) and Eye (7 items). The General health status module is intended to be administered to all patients with sarcoidosis. In addition to this, patients also complete organ specific modules if relevant to their condition. The individual module scores are intended to identify the health domains affected. The medication module can be used in isolation or combined with overall lung and skin health status questionnaires but not eye health status. The completion of the test consists of patients filling out the original seven-point Likert scale and scoring is calculated using a re-ordered scale for appropriate items. The KSQ module and overall (total) scores were transformed to a range of 0–100 [(actual score − lowest possible score/range) ×100], where 100 represents the best health status [10].

The aim of this study was to validate the KSQ in Serbian speaking population of sarcoidosis patients. The objective was also to compare the KSQ as disease-specific health status questionnaire with other already used questionnaires in sarcoidosis.

Material and methods

The study was conducted in the Clinic of Pulmonology, University Clinical Center of Serbia in Belgrade, Serbia, over the period of 6 months. Prior to the start of the study, the study had been presented to the Ethic committee of the Clinic of Pulmonology, University Clinical Center of Serbia, and the permission had been given.

Patients

A total of 159 biopsy positive sarcoidosis patients were enrolled into this study. All of the participants were diagnosed at the Clinic of Pulmonology of the University Clinical Center of Serbia, and were diagnosed by lung biopsy by bronchoscopy. The participation in the study was on voluntary basis, and prior to collecting the data, a written consent was acquired from the patients. All of the participants were of legal age (in Serbia 18-year-old and older), as our Clinic only treats adult patients, and did not have comorbidities that could impact the quality of life. The acquisition of all needed data was performed on their regular check-up, and the patients were chosen at random. Patients who had difficulty understanding the questions (such as illiterate patients), were not taken into consideration. Demographic data was collected, with classification of current organ involvement based on the ACCESS study [11]. Besides the demographic data, we also collected pulmonary function tests, other, previously validated tests, and the outcome of sarcoidosis.

Pulmonary function tests

On the same day patients completed the KSQ, performed spirometry tests on a pneumotachograph (Jaeger, Germany) with measures expressed as % of the reference values according to the ATS/ERS criteria [12]. Pulmonary function measurements included forced expiratory vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), peak expiratory flow (PEF). The transfer factor of the lung for carbon monoxide (DLCO) was measured using the single-breath method (Masterlab, Jaeger, Wurzburg, Germany).

Questionnaires

During the regularly scheduled outpatient clinic visit patients completed the Serbian version of King`s Sarcoidosis Questionnaire (KSQ), two standardized questionnaires for the measuring of health status: a generic measure–the fifteen-dimensional measure of health-related quality of life (15D) [13] and the Saint George Respiratory Questionnaire (SGRQ) [14], as well as Modified Medical Research Council (MRC) Dyspnea Scale, List of Daily Activities (DAL), and Fatigue Assessment Scale (FAS).

15D is an instrument for measurement of health-related quality of life [13]. It consists of 15 different and mutually exclusive health dimensions, each represented by one item [15, 16]. The total questionnaire score ranges between 0 and 1, where 1 signifies the highest level of health status. 15D was previously used in other diseases in multiple languages, and the Serbian version had been previously used in patients with asthma where it demonstrated good psychometric measurement properties [17].

SGRQ is an instrument that was originally designed to measure the health status of COPD patients [14]. Its validity, reliability, and responsiveness had been shown in other pulmonary diseases, including sarcoidosis [17]. The questionnaire consists of 50 items with 76 responses, and encompasses three domains of health status: 1) symptoms, with a special focus on respiratory symptoms; 2) activities, measuring decreased mobility or physical activity and 3) impacts, measuring the psychosocial influence of disease on the everyday life. Scores of these domains, as well as the total score, are scaled from 0 to 100, where higher scores represent higher decrease of quality of life.

Dyspnea was measured by the Modified Medical Research Council (MRC) Dyspnea Scale [18]. The MRC scale classifies subjects into one of five categories according to their degree of dyspnea while performing certain activities. Scores range from 0 to 4, with the higher scores indicating more severe dyspnea.

The degree of limitation in activities of daily living was evaluated with the List of Daily Activities (DAL) [19]. DAL has 11 items, all of which are related to everyday activities that a healthy individual can perform with no impairment. Higher the number of positive responses shows the higher degree of everyday impairment. DAL has been previously utilized in other chronic respiratory diseases, and the previously validated Serbian version has been used in patients with sarcoidosis [19, 20].

Fatigue Assessment Scale (FAS) is a scale specifically devised for measuring the fatigue, and can differentiate between physical and mental fatigue (5 items are related to physical, and 5 items are related to metal fatigue). The response scale is a 5-point scale (1 ‐ never to 5 ‐ always), and the score ranges between 10–50; the score bellow 22 is indicative of no fatigue.

As previously mentioned, all questionnaires except FAS have already been used in assessing symptom severity in Serbian population of sarcoidosis patients [21]. However, FAS has been validated in a broad spectrum of fatigue studies in sarcoidosis [4, 5]. The usage of other questionaries is to compare the results generated by previous, already validated, questionaries with KSQ, and, if any correlation was found, if one questionnaire (KSQ) can replace multiple questionnaires in everyday practice.

Clinical outcome of sarcoidosis

The clinical outcome of sarcoidosis has been defined by WASOG (World Association of Sarcoidosis and other Granulomatous diseases) task force in several clinical phenotypes based on clinical outcome in sarcoidosis patients (COS). To determine COS category, the patients had to be checked up on for a period of 5 years, as of the diagnosing the sarcoidosis [23].

The participants have been separated in nine COS categories, further placed in five groups, based on the current or previous need for systemic therapy, the resolution of the disease, and current status of the condition. The estimated COS groups are shown in Table 1.

Table 1. Clinical outcome in sarcoidosis patients.

	Never treated	No treatment for over a year	Asymptomatic	Symptomatic	Worsening in the last year
Resolved	COS 1	COS 2
Minimal disease	COS 3	COS 4
Persistent disease with no current treatment	COS 5	COS 6
Persistent disease with current treatment and no worsening			COS 7	COS 8
Persistent disease with current treatment					COS 9

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COS- clinical outcome in sarcoidosis patients

Questionnaire translation process

The original English version of the KSQ was officially translated and adopted into the Serbian language by two bilingual experts, working independently in translation form English to Serbian and vice versa. The items have been standardized with the help of physicians from the Serbian Association of Sarcoidosis (SAS), and who had previous experience with the English version of KSQ.

The backward version of the KSQ translation was emailed to the authors of the original KSQ (S Birring and A Patel), alongside with the original version, and the KSQ scores were calculated by one of the original coauthors. After comparing the translated version with the original, the original authors have given the permission for use.

After creating the final Serbian version, cognitive debriefing was performed; five patients and five physicians were chosen at random and were asked if they completely understand the questions from the KSQ. In addition, we asked both doctors and patients to write down their impressions about the new questionnaire. Furthermore, the doctors were asked to give a mark for the questionnaire at the scale from 0–5.

Here are doctors`comments about the KSQ, together with the marks.

Doctors’ comments about KSQ:

Milica Kontic, MD, PhD

I think that KSQ is clear, specific and very well formulated and that will be understandable to sarcoidosis patients and easy to fill out.

(5)

Ana Blanka, MD

I think that questionnaire is very good, because covers all aspects of sarcoidosis. Questions are clear, short and precise which makes this questionnaire understandable and easy to answer. Overview (appearance) is also very clear.

(5)

Jasmina Maric Zivkovic, MD, PhD

Symptoms from all sections are comprehensively (overall) presented. The questionnaire its self is very clear. The only remark: I would change is the order of questions in lung, medication and skin section. In medication and lung section the last question should be in the first place. I think that this sarcoidosis questionnaire is very good and useful. It’s not very long and our patients shouldn’t have any difficulties answering proposed questions.

(5)

Snezana Raljevic, MD

Questionnaire consists of 29 questions, divided into 5 subgroups: General health status, lungs, medications, skin and eyes. Questionnaire is short and clear. It wouldn’t’t take too long for a patient to answer. Questions are understandable to patients and almost all conditions were included that could affect quality of life of sarcoidosis patient. Questions and answers are very well designed so the patients themselves could fill out this questionnaire without any help from investigators.

My opinion is positive for KSQ and I would recommend it for use.

(5)

Aleksandra Dudvarski-Ilic, MD, PhD

Questions absolutely reflect the patients’ opinion about their disease. Almost all aspects of sarcoidosis are represented in this questionnaire that are important for patients. KSQ ic clear and overview is very good. Some terms in Serbian language could be more adjusted.

(4)

Patients about KSQ

Here we also considered patients`medical history, sarcoidosis duration and organ involvement. Additionally, patients were asked to give a mark for the questionnaire at the scale from 0–5.

O.M/ Age 31, sarcoidosis duration: 1-year, Current therapy: Prednisone

I think that this questionnaire includes most of the problems that sarcoidosis patients encounter. It’s very clear and easy to answer.

(5)

I.Dj/ Age 50, sarcoidosis duration: 1-year, Current therapy: No

This questionnaire covers all symptoms of our disease, and I didn’t have any difficulties answering these questions. I am also pleased that there are people who are trying to make our disease easier in this way.

(5)

S.D/Age74, sarcoidosis duration: 8 years, Current therapy: Prednisone+ Methotrexate

I have read this questionnaire very carefully and I think that includes a lot of symptoms that are related to sarcoidosis.

(5)

S. P/Age 56, sarcoidosis duration: 4 years, Current therapy: No

I think that based on my course of the disease this questionnaire covered the essence of sarcoidosis and all the symptoms and conditions sarcoidosis patient can experience.

(5)

D.J/Age 42, sarcoidosis duration: 5 years, Current therapy: Prednisone+ Methotrexate

Questions are precise, but I had hard time answering them. I believe the main lack of this questionnaire is that questions only consider 2-week period. I believe so, because while I am in a hospital, I rest all day and my symptoms are less there comparing when I am at home and having all my daily routine activities. I think real answers could be given when I am in my everyday environment.

(3)

It should be noted that the last patient was administered for the reevaluation of the disease, therefore the period which was not representative.

Statistical analysis

Descriptive statistics were calculated for the baseline demographic and clinical features. Continuous variables were presented as means with standard deviations and 95% confidence intervals (CI), while categorical variables are presented with numbers and percentages. Normality of distribution for continuous variables was tested with mathematical and graphical methods, depending on the variable.

Construct validity was examine using explanatory factor analysis. Factor extraction was performed using the Principal Components Analysis method with Varimax rotation. Correlation between the general and organ specific domains of KSQ and the corresponding questionnaires were determined using Spearman’s correlation coefficients. The internal consistency of the Serbian version of KSQ was assessed for multiple item scales by using Cronbach’s alpha coefficient (ranges from 0–1, the latter meaning perfect reliability).

Differences between KSQ scores in groups with acute and chronic sarcoidosis were analyzed using Students t-test (or Mann Whitney test) as appropriate. Correlation between KSQ scores with COS score, other questionnaires scores and lung functions were calculated using Pearson (or Spearman) correlation coefficient as appropriate. Sample size for correlation was calculated to detect at least correlation coefficient of 0.3, level of significance 0.05 and power of 80%. Therefore, the minimum required sample size for this study is 85. Recommended sample size for factor analysis is 5 to 10 cases per number of items. This rule taps the model precision, i.e., the ability of the parameter estimates to approximate true population values [22].

The level of significance was set at 0.05. Statistical analysis was performed using the IBM SPSS 21 (Chicago, IL, 2012) package.

Results

Results for explanatory factor analysis were presented in Table 2. Kaiser-Meyer-Olkin test for sampling adequacy: 0.894 and highly significant (p<0.001) Bartlett’s Test of Sphericity indicate that the application of factor analysis is adequate. By applying factor analysis, 5 factors were extracted, and which together explain 67.8% of the total variance. All five factors correspond to the five original modules. In the rotated factor matrix, item 1–7 and 10 items have the highest correlation with first domain, 12–16 with third, 20–22 with fifth, 23–25 with fourth, and 23–29 with second domain. Questions 8, 9 and 11 had highest correlation with fifth domain. The obtained structure corresponds to the original structure of the questionnaire with 5 domains and associated items. Correlation between the general and organ specific domains of KSQ and the corresponding questionnaires are presented in Table 3. Construct validity between the general and organ specific domains of KSQ and the corresponding questionnaires are presented in Table 3. Correlation between KSQ modules and SGRQ domains, DAL MRC, FAS and 15D scores was shown to be statistically significant, with the exception for medication and skin score. The correlations between the KSQ GHS and lung domain and all questionnaires (SGRQ domains, DAL MRC, FAS and 15D) were negative (r = -0.523 to -0.751). KSQ medication and skin score showed a negative, weak to moderate correlation with SGRQ domains, DAL MRC, FAS and 15D (r = -0.175 to ‐ 0.350). The Eyes module showed a negative, moderate to strong correlation with the other questionnaires (r = -0.382 to -0.574). KSQ organ modules combined with the GHS module all showed a moderate to strong correlation with the SGRQ domains, DAL MRC, FAS and 15D.

Table 2. Explanatory factor analysis-rotated component matrix.

	Component
question	1	2	3	4	5
1	0.711	0.339	0.311	0.061	0.126
2	0.773	0.275	0.168	0.058	0.116
3	0.723	0.162	0.146	0.054	0.255
4	0.704	0.227	0.385	0.07	0.03
5	0.814	0.218	0.233	0.02	0.043
6	0.596	0.219	0.362	0.194	-0.022
7	0.722	0.18	0.175	0.139	0.102
8	0.078	0.025	0.179	-0.027	0.663
9	0.466	-0.034	0.183	0.118	0.501
10	0.66	-0.008	0.329	0.025	0.159
11	0.341	0.256	0.275	0.092	0.386
12	0.436	0.177	0.745	0.093	0.131
13	0.42	0.173	0.802	0.117	0.16
14	0.49	0.214	0.678	0.035	0.188
15	0.39	0.216	0.749	-0.022	0.095
16	0.396	0.306	0.563	0.018	0.274
17	0.247	0.074	-0.106	0.278	0.718
18	0.367	0.209	-0.025	0.243	0.498
19	-0.102	0.177	0.218	0.125	0.687
20	0.073	0.13	0.08	0.928	0.106
21	0.145	0.207	0.085	0.894	0.092
22	0.075	0.085	0.004	0.856	0.241
23	0.221	0.775	0.06	0.081	0.065
24	0.29	0.736	0.127	0.143	-0.039
25	0.194	0.719	-0.048	0.215	0.106
26	0.097	0.795	0.136	0.034	0.14
27	0.109	0.773	0.296	0.018	0.113
28	0.197	0.807	0.206	0.118	-0.001
29	0.099	0.781	0.145	0.036	0.167

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Table 3. Correlation between the Serbian version of KSQ scores and other questionnaires.

	SGRQ ‐ SYMPTOMS	SGRQ ‐ ACTIVITY	SGRQ ‐ IMPACTS	SGRQ ‐ TOTAL SCORE	Score DAL	Score MRC	FAS total	Score15D
GHS score r p	-0.523 <0.001	-0.623 <0.001	-0.588 <0.001	-0.663 <0.001	-0.668 <0.001	-0.567 <0.001	-0.739 <0.001	-0.699 <0.001
Lung score r p	-0.576 <0.001	-0.704 <0.001	-0.677 <0.001	-0.751 <0.001	-0.742 <0.001	-0.623 <0.001	-0.688 <0.001	-0.623 <0.001
Med score r p	-0.350 <0.001	-0.175 0.036	-0.303 <0.001	-0.284 0.001	ns	ns	-0.292 <0.001	-0.284 0.001
Skin score r p	ns	ns	-0.157 0.051	ns	ns	ns	-0.290 <0.001	-0.172 0.032
Eyes score r p	-0.382 <0.001	-0.400 <0.001	-0.405 <0.001	-0.445 <0.001	-0.380 .002	-0.410 <0.001	-0.538 <0.001	-0.574 <0.001
GHS lung score r p	-0.579 <0.001	-0.698 <0.001	-0.664 <0.001	-0.743 <0.001	-0.747 <0.001	-0.621 <0.001	-0.767 <0.001	-0.714 <0.001
GHS skin score r p	-0.512 <0.001	-0.594 <0.001	-0.580 <0.001	-0.644 <0.001	-0.646 <0.001	-0.535 <0.001	-0.743 <0.001	-0.690 <0.001
GHS eyes score r p	-0.512 <0.001	-0.595 <0.001	-0.558 <0.001	-0.633 <0.001	-0.561 <0.001	-0.554 <0.001	-0.736 <0.001	-0.740 <0.001
GHS LS score r p	-0.560 <0.001	-0.668 <0.001	-0.650 <0.001	-0.721 <0.001	-0.715 <0.001	-0.591 <0.001	-0.773 <0.001	-0.709 <0.001
GHS LM score r p	-0.579 <0.001	-0.646 <0.001	-0.656 <0.001	-0.713 <0.001	-0.746 <0.001	-0.576 <0.001	-0.744 <0.001	-0.689 <0.001
GHS SM score r p	-0.513 <0.001	-0.526 <0.001	-0.567 <0.001	-0.604 <0.001	-0.597 <0.001	-0.472 <0.001	-0.705 <0.001	-0.651 <0.001
GHS LMS score r p	-0.555 <0.001	-0.611 <0.001	-0.636 <0.001	-0.683 <0.001	-0.710 <0.001	-0.546 <0.001	-0.745 <0.001	-0.686 <0.001

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GHS- General Health Status, LS- Lung Skin, LM- Lung Medication, SM- Skin Medication, LSM- Lung Skin Medication, ns- non significant, r- Spearman correlation coefficient, SGRQ- Saint George Respiratory Questionnaire, DAL- Daily Activity List, MRC- Medical Research Council dyspnea scale, FAS- Fatigue Assessment Scale

Internal reliability for KSQ translated version and original version are showed in Table 4. Cronbach’s α coefficients for lungs, skin and eye were higher in translated version of KSQ. Cronbach’s α for general health status and medication were lower in Serbian version of KSQ, when compare to original version. The same coefficient was used in the validation of the original test. Overall Cronbach’s α coefficient was 0.940.

Table 4. Internal reliability for KSQ translated version.

KSQ modules
	General health status	Lung	Skin	Eye	Medication
Number of items	10	6	3	7	3
Cronbach’s α coefficient (Original KSQ)	0.93	0.86	0.84	0.88	0.70
Cronbach’s α coefficient (Translated version of KSQ)	0.90	0.91	0.92	0.91	0.67

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KSQ- King’s sarcoidosis questionnaire

Average age for patients with sarcoidosis was 49.67±11.12 and 2/3 were female. The baseline characteristics of the 159 patients who participated in the study are shown in Table 5.

Table 5. Baseline characteristics of the study participants.

Variables	N (%)
Age (years), mean±sd (95% Confidence Interval)	49.67±11.12 (47.83–51.56)
Gender n (%)
Female	107 (67.3)
Male	52 (32.7)
Smoking n (%)
Non smoker	113 (71.1)
Ex smoker or smoker	46 (28.9)
Stage of the lung disease n (%)
0	43 (27.2%)
1	69 (43.0%)
2	37 (23.4%)
3	10 (6.3%)
Course of sarcoidosis n (%)
Acute	47 (26.9%)
Chronic	112 (70.4%)
Extrapulmonary sarcoidosis n (%)
Yes	45 (28.3%)
No	114 (71.7%)
Different organs involvement n (%)
Skin	8 (5.0%)
Eyes	3 (1.9%)
Liver	3 (1.9%)
Lymph node	6 (3.8%)
Spleen	4 (2.5%)
Heart	2 (1.2%)
CNS	19 (12%)
Medication n (%)
No therapy	71 (44.7%)
Prednisone	73 (45.9%)
Methotrexat	5 (3.1%)
Prednisone and Methotrexat	10 (6.3%)
sACE U/L, mean±sd (95% Confidence Interval)	51.32± 27.45 (46.61–56.03)
Lung function, mean±sd (95% Confidence Interval)
FVC (liter)	3.71±1.08 (3.49–3.84)
FVC (%)	105.50±16.94 (102.89–108.17)
FEV₁ (liter)	2.90±0.90 (2.73–3.02)
FEV₁ (%)	98.44±18.93 (94.87–101.15)
FEV₁/FVC	77.45±10.26 (75.93–79.30)
PEF (liter)	7.41±2.54 (7.04–7.86)
PEF (%)	102.69±21.62 (99.94–106.74)
DCo	8.02±5.88 (6.99–9.10)
DCo (%)	84.36±15.86 (81.51–87.01)
KCo	1.47±0.21 (1.44–1.52)

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CNS- central nervous system, ACE- angiotensin converting enzyme, FVC- functional vital capacity, FEV1- forced expiratory volume in fist second, PEF- peak expiratory flow, DCo- diffusion lung capacity for carbon-monoxide, KCo- Carbon monoxide transfer coefficient

Patients with chronic sarcoidosis showed statistically significant lower scores for all KSQ modules except for GHS and medication score. Also, GHS lung score was lower in chronic patients, difference was close to conventional level of significance (Table 6).

Table 6. KSQ scores in patients with different clinical course of sarcoidosis.

	N	mean±sd	p
GHS score
Acute	46	66.9±21.3	0.213
Chronic	112	62.1±23.6	0.213
Lung score
Acute	46	75.8±19.8	0.013
Chronic	112	66.2±25.2	0.013
Medication score
Acute	46	73.8±17.6	0.124
Chronic	99	67.9±26.7	0.124
Skin score
Acute	45	91.0±18.4	0.012
Chronic	110	81.3±27.8	0.012
Eyes score
Acute	45	83.4±18.8	<0.001
Chronic	110	68.4±26.7	<0.001
GHS lung score
Acute	46	70.5±18.8	0.058
Chronic	112	63.7±23.0	0.058
GHS skin score
Acute	46	70.5±18.9	0.045
Chronic	112	63.7±23.0	0.045
GHS Eyes score
Acute	45	73.9±15.7	0.003
Chronic	110	64.4±22.1	0.003
GHS Lung Skin score
Acute	45	74.1±16.2	0.015
Chronic	110	66.4±21.4	0.015
GHS Lung Medication score
Acute	44	70.5±16.7	0.047
Chronic	99	63.8±21.7	0.047
GHS Skin Medication score
Acute	43	72.8±15.3	0.049
Chronic	98	66.6±20.0	0.049
GSH Lung skin medication score
Acute	43	73.7±14.8	0.016
Chronic	98	62.2±20.5	0.016

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GHS- General Health status

For patients with follow up period more than 5 years, clinical outcome status (COS) was analyzed as they were classified into 9 categories (Table 7).

Table 7. Clinical outcome status and KSQ.

Sarcoidosis patients observed during five years (74 patients)
Resolved	Minimal Disease	Persistent sarcoidosis
COS 1 Never treated	COS 3 Never treated	No current therapy		Current therapy
COS 2 No therapy > One year 2pts	COS 4 No therapy > One year 9pts	COS 5 Never treated	COS 6 No therapy > One year 21pts	No worsening prior year	COS 9 Worsening in prior year 14pts
				COS 7 Asymptomatic 5pts
				COS 8 Symptomatic 23pts

Open in a new tab

COS- clinical outcome status

Correlation between lung function parameters, clinical outcome of sarcoidosis and KSQ scores correlation are presented in Table 8. There was no statistically significant correlation between FVC and KSQ modules. FEV 1 correlate positive statistically significant only with lung score. Positive, statistically significant correlation was observed between PEF and DLco with GHS, Lung, Eye, GHS Lung, GHS Skin score, GHS Eye, GHS Lung Skin, GHS Lung Medication, GHS Skin Medication and GHS Lung Skin Medication score. Statistically significant negative correlation between COS score and KSQ lung, GSH Lung, GSH S, GSH LM, GSH SM, GSH LMS were observed. Negative, moderate statistically significant correlation was observed between COS score and medication score. Correlation between COS and GSH score was negative and close to conventional level of significance. There was no statistically significant correlation between skin, eyes, GHS Eye and COS score.

Table 8. Correlation between lung function parameters, clinical outcome of sarcoidosis and KSQ.

KSQ	Lung function parameters
KSQ	FVC (%)	FEV₁ (%)	PEF (%)	DLco (%)	Clinical outcome of sarcoidosis
GHS score r p	Ns	ns	0.252 0.001	0.289 <0.001	ns
Lung score r p	Ns	0.168 0.034	0.290 <0.001	0.343 <0.001	-0.236 0.042
Medication score R p	ns	ns	ns	ns	-0.369 0.002
Skin score r p	ns	ns	ns	ns	ns
Eye score r p	Ns	ns	0.177 0.027	0.230 0.004	ns
GHS Lung score r p	Ns	ns	0.285 <0.001	0.332 <0.001	-0.256 0.027
GHS Skin score r p	Ns	ns	0.223 0.005	0.305 <0.001	-0.235 0.037
GHS Eye score r p	Ns	ns	0.259 0.001	0.315 <0.001	ns
GHS Lung Skin score r p	Ns	ns	0.259 0.001	0.345 <0.001	-0.245 0.037
GHS Lung Medication score r p	Ns	ns	0.251 0.002	0.380 <0.001	-0.286 0.020
GHS Skin Medication score r p	Ns	ns	0.185 0.027	0.343 <0.001	-0.289 0.020
GHS Lung Skin Medication score r p	Ns	ns	0.227 0.007	0.387 <0.001	-0.283 0.002

Open in a new tab

KSQ- King’s sarcoidosis questionnaire, GHS- General health status, ns- non significant, r- Pearson correlation coefficient, FVC- functional vital capacity, FEV1- forced expiratory volume in fist second, PEF- peak expiratory flow, DLCO- diffusion lung capacity for carbon-monoxide

Discussion

The original English version of Kings Sarcoidosis Questionnaire, with its five modules, had shown to be useful modular health status measure to be used in everyday clinical practice. Being a multimodular tool, depending on the afflicted organs, the physician can apply certain, or all modules in evaluating the state of the patient. The General Health Status module could be utilized in all forms of the disease, and, although being the most nonspecific, could be used in comparing different subpopulations of patients with sarcoidosis. During the creation of the Serbian version, we have appropriated all 29 items of the original version into Serbian language, and in doing so, we have allowed the Serbian version to be utilized in further potential cross-center studies. The internal reliability analyzed using Cronbach’s α coefficient had shown similar results to the English version, as seen in the results section, which further proves the utility of Serbian version.

We have further compared the Serbian version of KSQ with other, standardized, questionnaires, and have shown strong correlation in all fields. SGRD and 15D are general quality of life questionnaires, already in use with both sarcoidosis patients and with other chronic patients, and two of the most common symptoms, dyspnea and fatigue, have their own separate questionnaires (MRS and FAS, respectively). The advantage of KSQ is that all of these results could be generated from one questionnaire, which leads to improved communication with the patients.

KSQ scores generated in this study have shown a statistically significant difference between patients with acute and chronic forms of the disease; the patients with the chronic form have shown significantly worse results as compared to those with acute form, and the difference is present virtually all items. As is to be expected, patients with the chronic form have a higher chance to develop more severe forms of the pulmonary sarcoidosis, as well as extra pulmonary forms, both of which lead to significant decrease in quality of life, especially stage IV pulmonary sarcoidosis, neurosarcoidosis and cardiac sarcoidosis.

It should be noted there is another commonly used questionnaire in everyday practice- Sarcoidosis Health Questionnaire (SHQ), developed prior to KSQ [23]; this questionnaire has 29 items, and is to be utilized in its entirety. The original authors of KSQ have already compared the two questionnaires, and have found certain limitations of SHQ: unlike KSQ, SHQ cannot be tailored to individual phenotypes, SHQ has fewer items that evaluate fatigue, medication and extra pulmonary organs, with no validation for the usage in skin and eye disease. It also should be noted that different methodology has been used in validation of the questionnaires: KSQ with Rasch analysis and SHQ with clinical impact methodology, concurrent validity was higher in KSQ, and a stronger relationship was present between KSQ and SGRQ, as well as KSQ and MES dyspnea score. KSQ has also shown a higher test/retest value, the same was not present in SHQ [10]. During the creation of the Serbian version, we have taken into consideration the previously noted differences between KSQ and SHQ, and have not compared Serbian versions of these tests.

KSQ has been validated in both German and Dutch languages [24, 25]. The authors from the Netherlands have shown good internal consistency for all KSQ, and intraclass correlation coefficients and Bland-Altman plots showed good repeatability of the KSQ, therefore the test was successfully validated for Dutch language [24]. The original English version had 29 models, and in order to fulfil the requirements of the Rasch model, but the German version had to reduce the total number of models to 24; however, the original 29 version can still be used to compare data to international version [25].

There are certain limitations during the creation of the Serbian version. As the original authors have noted, during the creation of quality-of-life questionnaires, it is possible that certain characteristics have not been taken into consideration, but can be an important segment in patient’s life. The quantity of items is also of importance; it is difficult to create a questionnaire of the least number of items, as it could be used in everyday practice, which still maintains its validity. Another point of interest is the interpretation of side effects of therapy. It is not always possible to differentiate the impairment of quality of life caused by the side effects of treatment and the disease, as noted by the authors [10]. One of the important parts when validating any questionnaire is measuring the minimal clinical important difference (MCID) which is defined by the smallest amount of change that is relevant to patients and would indicate the success or detriment of an intervention or warrant changes in the care plan [25]. A study was performed where MCID was calculated for two major domains of the KSQ (the general health and pulmonary-specific). The study had taken into analysis several questionnaires (KSQ, SGRQ, FAS and the Short Form-36) with physiological tests (FVC and six-minute-walk tests). They identified very weak correlations between KSQ scores and physiological (FVC and six-minute-walk tests) measures of the severity of pulmonary sarcoidosis. We have shown a strong correlation between physiological tests and KSQ score, however we have not performed a follow-up, and therefore we could not give our conclusion. A precise MCID has yet to be discovered for KSQ [26, 27].

Conclusion

As the authors of the original study have shown, the questionnaire is a quick and valid tool to identify health status issues important to patients, and can be used to help formulate shared care plans between the patient and physician. The Serbian version of KSQ has shown an important step towards analyzing the quality of life in patients with sarcoidosis, and allows the comparison between centers internationally. Being translated, this version can be used by both physicians and patients that do not speak English, which will lead to the increase of data generation, and will lead to better understanding of quality of life in this disease. It should be noted that the questionnaire should not be used isolated, and should be improved with clinical presentation, radiological and functional tests and other questionnaires. As the original version undergoes reevaluation and improvement, so will the Serbian version.

Supporting information

S1 File

(SAV)

Click here for additional data file.^{(62.2KB, sav)}

S2 File

(DOCX)

Click here for additional data file.^{(16.9KB, docx)}

S3 File

(DOCX)

Click here for additional data file.^{(13.6KB, docx)}

Data Availability

All relevant data are within the paper and its Supporting Information files.

Funding Statement

The author(s) received no specific funding for this work.

References

1.Hunninghake GW, Costabel U, Ando M et al. ATS/ERS/WASOG statement on sarcoidosis. American Thoracic Society/European Respiratory Society/World Association of Sarcoidosis and other Granulomatous Disorders. Sarcoidosis Vasc Diffuse Lung Dis 1999; 16:149–73. [PubMed] [Google Scholar]
2.Baughman RP, Culver DA, Judson MA. A Concise Review of Pulmonary Sarcoidosis. Am J Respir Crit Care Med 2011; 183:573–581. doi: 10.1164/rccm.201006-0865CI [DOI] [PMC free article] [PubMed] [Google Scholar]
3.Cox CE, Donohue JF, Brown CD et al. Health-related quality of life of persons with sarcoidosis. Chest 2004; 125:997–1004. doi: 10.1378/chest.125.3.997 [DOI] [PubMed] [Google Scholar]
4.Drent M, Lower E. De Vries J. Sarcoidosis-associated fatigue. Eur Respir J 2012; 40:255–263. [DOI] [PubMed] [Google Scholar]
5.De Kleijn WPE, Drent M, Vermunt JK, Shigemitsu H, De Vries J. Types of fatigue in sarcoidosis patients. Journal of Psychosomatic Research 2011; 71:416–422. doi: 10.1016/j.jpsychores.2011.09.006 [DOI] [PubMed] [Google Scholar]
6.Te HS, Perlman DM, Shenoy C et al. Clinical characteristics and organ system involvement in sarcoidosis: comparison of the University of Minnesota Cohort with other cohorts. BMC Pulm Med. 2020. Jun 1;20(1):155. doi: 10.1186/s12890-020-01191-x [DOI] [PMC free article] [PubMed] [Google Scholar]
7.Judson MA, Preston S, Hu K et al. Quantifying the relationship between symptoms at presentation and the prognosis of sarcoidosis. Respir Med. 2019 Jun;152: 14–19. doi: 10.1016/j.rmed.2019.03.012. Epub 2019 Mar 23. . [DOI] [PubMed] [Google Scholar]
8.Wirnsberger RM, Drent M, Hekelaar N, et al. Relationship between respiratory muscle function and quality of life in sarcoidosis. Eur Respir J 1997; 10:1450–1455. doi: 10.1183/09031936.97.10071450 [DOI] [PubMed] [Google Scholar]
9.De Vries J, Drent M. Quality of life and health status in sarcoidosis: a review. Semir Respir Crit Care Med 2007; 28(1):121–7. doi: 10.1055/s-2007-970337 [DOI] [PubMed] [Google Scholar]
10.Patel AS, Siegert RJ, Creamer D et al. The development and validation of the King’s Sarcoidosis Questionnaire for the assessment of health status. Thorax 2013; 68(1):57–65. doi: 10.1136/thoraxjnl-2012-201962 [DOI] [PubMed] [Google Scholar]
11.Judson MA, Baughman RP, Teirstein AS et al. Defining organ involvement in sarcoidosis: the ACCESS proposed instrument. ACCESS Research Group. A Case Control Etiologic Study of Sarcoidosis. Sarcoidosis Vasc Diffuse Lung Dis 1999; 16:75–86. [PubMed] [Google Scholar]
12.Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spiromerty. ATS/ERS Task Force: Standardization of Lung Function Testing. Eur Respir J 2005; 26:319–338. [DOI] [PubMed] [Google Scholar]
13.Sintonen H, Pekurinen M. A fifteen-dimensional measure of health-related quality of life (15D) and its applications. In: Walker SR, Rosser R, editors. Quality of life assessment: key issues in 1990s. Dordrecht: Kluwer Academic Publishers; 1993. p. 185–95. [Google Scholar]
14.Jones PW, Quirk FH, Baveystock CM, et al. A self-complete measure of health status for chronic airflow limitation. The St George’s respiratory questionnaire. Am Rev Respir Dis 1992; 145:1321–7. [DOI] [PubMed] [Google Scholar]
15.Sintonen H. The 15D-measure of health-related quality of life: I: reliability, validity and sensitivity of its health state descriptive system: working paper 41. Melbourne, Australia: National Centre for Health Program Evaluation; 1994. [Google Scholar]
16.Sintonen H. The 15D-measure of health-related quality of life II: feasibility, reliability and validity of its valuation system: working paper 42. Melbourne, Australia: National Centre for Health Program Evaluation; 1994. [Google Scholar]
17.Chang JA, Curtis J. R, Patrick DL, Ragh G. Assessment of Health-Related Quality of Life in Patients with Interstitial Lung Disease. CHEST 1999; 116:1175–1182. doi: 10.1378/chest.116.5.1175 [DOI] [PubMed] [Google Scholar]
18.Medical Research Council. Questionnaire on respiratory symptoms: instructions to interviewers. MRC committee on environmental and occupational health. London: MRC; 1986. [Google Scholar]
19.Stewart AL, Ware JE, Brook RH. Advances in the measurement of functional status: construction of aggregate indexes. Med Care 1981; 19:473–88. doi: 10.1097/00005650-198105000-00001 [DOI] [PubMed] [Google Scholar]
20.Gvozdenovic BS, Mihailovic-Vucinic V, Ilic-Dudvarski A, Zugic V, Judson MA. Differences in symptom severity and health status impairment between. patients with pulmonary and pulmonary plus extrapulmonary sarcoidosis. Respir Med 2008; 102:1636–1642. [DOI] [PubMed] [Google Scholar]
21.Baughman RP, Nagai S, Balter M, et al. Defining the clinical outcome status (COS) in sarcoidosis: results of WASOG Task Force. Sarcoidosis Vasc Diffuse Lung Dis 2011; 28:56–64. [PubMed] [Google Scholar]
22.Bentler P., Chou C. Practical Issues in Structural Modeling. Sociological Methods & Research 1987, 16(1), 78–117. 10.1177/0049124187016001004 [DOI] [Google Scholar]
23.Cox CE, Donohue JF, Brown CD et al. The Sarcoidosis Health Questionnaire: a new measure of health-related quality of life. Am J Respir Crit Care Med 2003; 168:323–9 doi: 10.1164/rccm.200211-1343OC [DOI] [PubMed] [Google Scholar]
24.Van Manen MJ, Wapenaar M, Strookappe B, et al. Validation of the King’s Sarcoidosis Questionnaire (KSQ) in a Dutch sarcoidosis population. Sarcoidosis Vasc Diffuse Lung Dis. 2016. Mar 29;33(1):75–82. . [PubMed] [Google Scholar]
25.Farin E, Heyduck K, Frye BC et al. Translation and psychometric properties of the King’s Sarcoidosis Questionnaire (KSQ) in German language. Health Qual Life Outcomes. 2019. Apr 11;17(1):62. doi: 10.1186/s12955-019-1131-z ; PMCID: PMC6460543. [DOI] [PMC free article] [PubMed] [Google Scholar]
26.McGlothlin AE, Lewis RJ. Minimal clinically important difference: defining what really matters to patients. JAMA 2014; 312:1342–1343. doi: 10.1001/jama.2014.13128 [DOI] [PubMed] [Google Scholar]
27.Baughman RP, Judson MA, Beaumont JL, Maier LA, Sweiss NJ, Culver DA, et al. Evaluating the minimal clinically important difference of the King’s Sarcoidosis Questionnaire in a multicenter prospective study. Ann Am Thorac Soc 2021; 18:477–485. doi: 10.1513/AnnalsATS.202006-607OC [DOI] [PubMed] [Google Scholar]

PLoS One. doi: 10.1371/journal.pone.0273126.r001

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PONE-D-22-20583King’s Sarcoidosis Questionnaire (KSQ) – Validation study in non-English speaking population of sarcoidosis patientsPLOS ONE

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Reviewer #1: King’s Sarcoidosis Questionnaire (KSQ) – Validation study in non-English speaking population of sarcoidosis patients

. This submission is based on substantial research efforts, so it may be suitable for publication in Journal after revising. This article is strongly recommended for publication after incorporating certain changes. This article needs thorough proofreading. Overall quality of Language is good. Just minor grammatical mistakes are found. All tables and figures are relevant. Research Methodology has been well defined. All data are aligned to the findings of the research. This article is good attempt in the field research and will be beneficial for future researchers.

Reviewer #2: This manuscript will greatly benefit from proofreading and language editing.

1. Abstract: The Introduction section of the abstract is quite long. Even longer than the methods. Streamline your thought to introduce your topic and the gap of the literature. Be direct to only identify the objectives and any other specific objectives. In the methods, identify whether the instrument was self-answered, and what statistical analysis was performed.

2. The introduction lacks focus on the King’s Sarcoidosis Questionnaire. There was even a mention of another questionnaire that was irrelevant to the study. The authors will need to organize their thought process more and determine the need for using this questionnaire, its constructs, evidence of its psychometric properties, and the need to contextualize.

3. I am confused whether this is a psychometric study or a cross-sectional study. The aim does not match the methodology identified.

4. Include the specific ethical approval number and IRB information.

5. Restructure the Methods section. It is quite confusing how several similar information can be in separate subheadings.

6. What is the rationale behind the other questionnaires?

7. What was the reference used to inform the process translation of the questionnaire? Shouldn't this be the first phase of the study?

8. How is internal reliability in the results section different from internal consistency?

9. What was the basis for interpreting the patients' scores to be low on the KSQ?

10. Overall the results section was confusing. Once the authors explicitly describe their objective/s, this section may be better constructed following those for better clarity and coherence.

11. Limit your discussion to the study's findings grounded on your objectives.

12. What key messages on the KSQ are your pertaining to?

13. To claim the suitability in non-English speaking population is an over-inflation of your findings, which was contextualized to your setting. You do not have any proof that apart from the ethnicity/culture of the patients recruited in study, the same psychometric properties will be the same in others.

Reviewer #3: 1) The introduction part : the authors should identify the significant problem or advantage of Sarcoidosis symptom diagnostic in this article target.

2) According to examine the construct validity by using Spearman's correlation coefficient thus the authors should describe how to calculate the sampling size or describe the sampling technique. In addition, the authors should identify the criteria for selected the participant and reject the participant in this research.

3) Due to this research conduct with non English speaking the authors should examine the translate validation in any scale that is used in this research. Moreover, should examine the reliability by using test retest between English scale and translated scale.

4) According to this research construct validity by using Spearman's correlation coefficient that questionable seem like concurrent validity technique

Reviewer #4: The review article topic: King’s Sarcoidosis Questionnaire (KSQ) – Validation study in non-English speaking population of sarcoidosis patients. This submission is based on substantial research efforts, so it may be suitable for publication in Journal after revising. This article is strongly recommended for publication after incorporating certain changes. This article needs thorough proofreading. The overall quality of the Language is good. Just minor grammatical mistakes are found. All tables and figures are relevant. The research Methodology has been well defined. All data are aligned with the findings of the research. This article is a good attempt at field research and will be beneficial for future researchers.

Reviewer #5: Although the translation of the test into other societies with linguistic and cultural differences is important and appropriate for research to be published in international journals, But the composition of this article is still far from the standard of this journal. Authors need to revamp most of the content to be resubmitted.

Reviewer #6: Dear Authors,

This paper investigated the on PLOS ONE manuscript "King’s Sarcoidosis Questionnaire (KSQ) – Validation study in non-English speaking population of sarcoidosis patients." I think this paper needs minor revision to improve the rationale and gap of the study. Specific comments for each section are below:

Introduction

Page 4, I am not clear about why physicians and patients did not agree in the symptoms of sarcoidosis. Please clarify this point or add the issue related to symptoms between physicians and patients.

Page 4, Give relevant reasons why your team choose “the King’s Sarcoidosis Questionnaire (KSQ)” rather than the Sarcoidosis Health Questionnaire. You mention about 80% of them were African Americans in the study. Why will be affected your study?

Please showed outstanding points are the reasons KSO from England that would be possible to synthesize the aim of your study.

Methods

Page 8, The comprehensive survey, or questionnaire survey is important that you need to clarify how to translate the needed evidence or method to support it (Translation process), one mother tongue expert should be in the field of health professional.

Page 10, After obtaining the final Serbian version, you provided it to a pilot study (Five patients and five physicians). However, the next process will be the inclusion and exclusion criteria that I cannot see. You needed to show this relevant point on the method as well. For example, you need to set up the age rank of your patients, etc. It will help you to show the outcome of results in the demographic table (Table 3) in the result section.

Discussion

Page 14, your opinion further studies are necessary to distinguish the components of fatigue (mental and physical) in correlation with KSQ. You mentioned these points, please clarify why the future KSQ Serbian version should be distinguished the physical and mental fatigues in this questionnaire.

Page 14, Please rewrite “The German version required the reduction of models, from original 29 to 24, to fulfill the requirements of the Rasch model; however, the original 29 version can still be used to compare data to the international version [36].”

The readers may be confused about “29 to 24”, needs to be clarified what is it (items). And “the original 29 version”, please rewrite to be clear.

Reviewer #7: Overall, a well-written article that could use some polishing in terms of packaging and flow. The authors may also want to add research implications.

Methods:

Sampling methodology needs elaboration.

The research method is explained in detail and is easy to understand.

Testing the validity and reliability of the instrument can be used.

Results:

The results of the study have been well explained by the author and are supported by valid primary data and appropriate conclusions.

Reviewer #8: Abstract

- Results: summary of statistic analysis should be added.

Objectives: The author should use the word consistency (aim or objective).

Methods: Re-arrange this section.

Patient: If patients incompleted the questionnaire, were they withdrawn from the study?

Add number of study approved.

There is no need to write doctors and patients' comments.

Results: Re-arrange this section.

Discussion: Begin with a clear statement.

Be concise.

Reviewer #9: 1) Abstract

- please paraphrase this sentence - Despite the studies performed

with the aim to find out the reliable tools for assessment the disease severity or its

progression, up to date there is no reliable tool for assessing the impact of sarcoidosis on

patients’ health status and the impact of the therapy.

- Sarcoidosis health Questionnaire, created by Christopher Cox and coworkers (year?)

2) Introduction

- should highlight the need of a new assessment for measuring health status in sarcoidosis.

- what are the weakness of the current assessment.

3) Methods

- authors should rewrite the way they present the translation process espcially re doctors' comments to a more sound academic writing.

Reviewer #10: Comment to authors

This article provides the validation results of the King’s Sarcoidosis Questionnaire (KSQ) in the non-English speaking population of sarcoidosis patients. The manuscript has limitations on language usage as there were a lot of non-academic and awkward sentences. It would be good if the authors could revise the manuscript to make it more precise and constructive. In my opinion, this paper requires significant revision. I hope my comments and suggestions below are helpful.

• The authors should reconsider the title of this research to be specific to the sample of the current study (Serbian) instead of using non-English speaking.

• Abstract; no need to mention another questionnaire that was not used in the current study.

Introduction

• The Introduction is too short. The authors should provide more rationale for research gap.

• A comprehensive literature review should be provided to reveal the correlation between the quality of life and sarcoidosis patients’ life

• Please provide the rationale for choosing the King’s Sarcoidosis Questionnaire (KSQ) over the Sarcoidosis Health Questionnaire.

• Please add more information on previous cross-cultural studies that examined the psychometric properties of the KSQ.

Methods

• Please give detail on the inclusion and exclusion criteria used. It’s not clear in the methods.

• Please provide more information on sample recruitment and the rational of enrolling samples 18 years and older.

• Please revise the Methods section to be more structured and clearer, particularly on Questionnaire

• ‘Questionnaire’ should be on the sub-heading not ‘ questionnaire used in this study’

• Please provide psychometric properties, i.e. internal consistency of all questionnaires used in the current study

• In the back translation process, two bilinguals who expertise both in English and Serbian are needed, not only two mother tongue experts

• No need to mention the full name of the person who scored the KSQ on the manuscript

• In my opinion, the authors should provide only the Item-Objective Congruence (IOC) results instead of giving all doctors’ comments on the manuscript

Statistical analysis

• Please elaborate statistical analysis more precise and clearly

• Please provide how missing data was handled

• Description of results of normality of distribution should be evident in the section

Results

• There are many questionnaires used in the current study and also an abbreviation, therefore the authors should consider reporting results more precise and clearly by using table

Discussion

• The first paragraph of the Discussion should be moved to Introduction

• No need to repeat all the results of the discussion.

• The discussion needs to improve and add information on the strengths and limitations of the study.

• Please add the information about the clinical application of this study.

• As this current study examines convergent validity and internal consistency, it could not be concluded that the KSQ is a reliable and valid tool. The findings should be interpreted with caution regarding the limitation. Other psychometric properties, e.g. test-retest reliability, criterion validity, and construct validity of the KSQ should also be examined.

**********

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

Reviewer #4: No

Reviewer #5: Yes: Kittisak JERMSITTIPARSERT

Reviewer #6: No

Reviewer #7: No

Reviewer #8: Yes: Natwipa Wanicharoen, PhD.

Reviewer #9: No

Reviewer #10: No

**********

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PLoS One. 2023 Sep 5;18(9):e0273126. doi: 10.1371/journal.pone.0273126.r002

Author response to Decision Letter 0

1 Nov 2022

To whom it may concern,

We have taken into consideration the points raised by the academic editor and reviewers, and have corrected accordingly.

• The majority of the article has been rewritten, as to improve the quality of language.

• The title of the article has been changed, as to be more specific (from “non-English” to “Serbian”).

• We have removed the other questionnaire that was not used in the study from the Abstract.

• We have expanded the introduction as to emphasize the need for a quality-of-life questionnaire.

• The ethical aspect, as well as the inclusion and exclusion criteria have been expanded upon in material and methods section.

• Other questionnaires that have been used for comparison have been explained as well as rationale behind using them in the material and methods section.

• We have removed the results from the discussion section.

• The limitations of the study have been noted in the discussion section.

• Clinical application of the questionnaire has been explained in the conclusion.

• The versions of KSQ in other languages were discussed, and the rationale for using the KSQ over Sarcoidosis Health Questionnaire was explained.

We hope that our changes to the article will suffice, and that our altered article will meet the criteria for publication.

The autors

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PLoS One. doi: 10.1371/journal.pone.0273126.r003

Decision Letter 1

Supat Chupradit

22 Nov 2022

PONE-D-22-20583R1King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patientsPLOS ONE

Dear Dr. Stjepanovic,

Please submit your revised manuscript by Jan 06 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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We look forward to receiving your revised manuscript.

Kind regards,

Supat Chupradit, Ph.D., M.Ed., B.Sc.(OT), B.P.A., B.Ed., B.A.

Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

Reviewer #4: All comments have been addressed

Reviewer #6: All comments have been addressed

Reviewer #7: All comments have been addressed

Reviewer #8: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #6: Yes

Reviewer #7: Yes

Reviewer #8: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: No

Reviewer #4: Yes

Reviewer #6: Yes

Reviewer #7: Yes

Reviewer #8: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #6: Yes

Reviewer #7: Yes

Reviewer #8: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

Reviewer #4: Yes

Reviewer #6: Yes

Reviewer #7: Yes

Reviewer #8: Yes

**********

6. Review Comments to the Author

Reviewer #1: King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients. Overall clear and follow by reviewer comments. Accept

Reviewer #2: It is quite difficult to re-review the manuscript without the authors' point-by-point response to my previous comment. It is for this mater that I retain my previous comments on the manuscript.

Reviewer #3: 1-The authors aim to validate the construct validity of research tools. The construct validity that might be found by using Exploratory factor analysis and comfirmatory factor analysis. In another way we found by using expert judgement . The Pearson product moment correlation is not the method for construct validation. This method is used only for concurrent validation or predictive validation in research tools. The authors should consider the method for found the psychometic propertrict of reserch tools.

2-We found the negative correration and lower correlation. Therefore, the authors might describe indept why and how was ??

3-the method of sampling size for using Pearson correlation should calculate the power of test, error, effectsize, and level of statistically significant levels.

Reviewer #4: Thank you for considering reviewer comments and suggestions. I am satisfied with the responses.

All the best for your article.

Reviewer #6: Dear Authors,

This paper investigated the PLOS ONE manuscript "King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients."

The manuscript revision has been improved; all the queries have been answered appropriately. The authors had already responded to the main concerns and relevant issues. I found this work to be persuasive and consistent with scholarly intent and intellectual passion to contribute to supporting sarcoidosis patients in Serbia.

One recommendation for further study would be to utilize the treatment (before-after), which can strengthen your work and benefit sarcoidosis patients in Serbia.

I recommended this work for publication or no revision.

Thank you very much

Reviewer

Reviewer #7: It is encouraged to publish this article after making certain adjustments. The article need a thorough proofread. Frequently, the language is of high quality. Minor grammatical errors are the only ones that have been found. Each graph and table is relevant. Research technique is clearly defined. The findings of the study agree with all of the information. The excellent research effort put out in this essay will be advantageous to upcoming researchers.

Reviewer #8: all comments have been addressed. The authors have adequately addressed comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication

**********

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

Reviewer #4: No

Reviewer #6: No

Reviewer #7: No

Reviewer #8: No

**********

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PLoS One. 2023 Sep 5;18(9):e0273126. doi: 10.1371/journal.pone.0273126.r004

Author response to Decision Letter 1

5 Jan 2023

As requested, all of the changes were implemented in the paper, with specifics noted in the Response to Reviewers file

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PLoS One. doi: 10.1371/journal.pone.0273126.r005

Decision Letter 2

Gernot Zissel

6 Mar 2023

PONE-D-22-20583R2

King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

PLOS ONE

Dear Dr. Stjepanovic,

I am sorry, but I stepped into this review process, as the former Academic Reviewer is no longer available. Therefore I do not have full knowledge on the history of this manuscript. To me it seems that most of the concerns are sufficiently answered; however, reviewer 2 still has some open questions to be clarified. Thus, I would like to ask you to amend your manuscript according to the reviewer's suggestions wherever possible and necessary. Please send us a detailed point-by-point answer to the reviewers comments.

Please ensure that your decision is justified on PLOS ONE’s publication criteria and not, for example, on novelty or perceived impact.

For Lab, Study and Registered Report Protocols: These article types are not expected to include results but may include pilot data.

==============================

Please submit your revised manuscript by Apr 20 2023 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Supat Chupradit, Ph.D., M.Ed., B.Sc., B.P.A., B.Ed., B.A.

Academic Editor

PLOS ONE

Journal Requirements:

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: (No Response)

Reviewer #3: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Partly

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Reviewer #2: 1. The rationale behind the need to test KSQ in a Serbian population should be placed in the Introduction and not in the methods section.

2. Consider placing the estimated COS groups in a table.

3. Why was back translation not performed prior to cognitive interviewing?

4. How did the authors resolved the rating of (3) made by the last participant?

5. How robust was the sample size? Conducting factor analysis usually recruits 20--300 participants or 10 participants x number of items.

7. Were the five components used in the EFA correspond to the five modules of the KSQ?

8. Why was an overall internal consistency cronbach's alpha not computed?

Reviewer #3: well revise version

the authors should design the data table that should consist the only significant data.

**********

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Reviewer #2: No

Reviewer #3: No

**********

PLoS One. 2023 Sep 5;18(9):e0273126. doi: 10.1371/journal.pone.0273126.r006

Author response to Decision Letter 2

8 Apr 2023

We hope that we have successfully responded to your suggestions, and that our paper is now up to PLOS ONE standards. All of the changes are noted in the manuscript with track changes, and in a separate file, as requested.

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PLoS One. doi: 10.1371/journal.pone.0273126.r007

Decision Letter 3

Gernot Zissel

24 Apr 2023

King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

PONE-D-22-20583R3

Dear Dr. Stjepanovic,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

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Gernot Zissel, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

Reviewer #2: Yes

**********

6. Review Comments to the Author

Reviewer #2: (No Response)

**********

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Reviewer #2: No

**********

PLoS One. doi: 10.1371/journal.pone.0273126.r008

Acceptance letter

Gernot Zissel

25 Aug 2023

PONE-D-22-20583R3

King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

Dear Dr. Stjepanovic:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

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Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

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on behalf of

Prof. Dr. Gernot Zissel

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PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

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Data Availability Statement

All relevant data are within the paper and its Supporting Information files.

[pone.0273126.ref001] 1.Hunninghake GW, Costabel U, Ando M et al. ATS/ERS/WASOG statement on sarcoidosis. American Thoracic Society/European Respiratory Society/World Association of Sarcoidosis and other Granulomatous Disorders. Sarcoidosis Vasc Diffuse Lung Dis 1999; 16:149–73. [PubMed] [Google Scholar]

[pone.0273126.ref002] 2.Baughman RP, Culver DA, Judson MA. A Concise Review of Pulmonary Sarcoidosis. Am J Respir Crit Care Med 2011; 183:573–581. doi: 10.1164/rccm.201006-0865CI [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0273126.ref003] 3.Cox CE, Donohue JF, Brown CD et al. Health-related quality of life of persons with sarcoidosis. Chest 2004; 125:997–1004. doi: 10.1378/chest.125.3.997 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref004] 4.Drent M, Lower E. De Vries J. Sarcoidosis-associated fatigue. Eur Respir J 2012; 40:255–263. [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref005] 5.De Kleijn WPE, Drent M, Vermunt JK, Shigemitsu H, De Vries J. Types of fatigue in sarcoidosis patients. Journal of Psychosomatic Research 2011; 71:416–422. doi: 10.1016/j.jpsychores.2011.09.006 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref006] 6.Te HS, Perlman DM, Shenoy C et al. Clinical characteristics and organ system involvement in sarcoidosis: comparison of the University of Minnesota Cohort with other cohorts. BMC Pulm Med. 2020. Jun 1;20(1):155. doi: 10.1186/s12890-020-01191-x [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0273126.ref007] 7.Judson MA, Preston S, Hu K et al. Quantifying the relationship between symptoms at presentation and the prognosis of sarcoidosis. Respir Med. 2019 Jun;152: 14–19. doi: 10.1016/j.rmed.2019.03.012. Epub 2019 Mar 23. . [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref008] 8.Wirnsberger RM, Drent M, Hekelaar N, et al. Relationship between respiratory muscle function and quality of life in sarcoidosis. Eur Respir J 1997; 10:1450–1455. doi: 10.1183/09031936.97.10071450 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref009] 9.De Vries J, Drent M. Quality of life and health status in sarcoidosis: a review. Semir Respir Crit Care Med 2007; 28(1):121–7. doi: 10.1055/s-2007-970337 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref010] 10.Patel AS, Siegert RJ, Creamer D et al. The development and validation of the King’s Sarcoidosis Questionnaire for the assessment of health status. Thorax 2013; 68(1):57–65. doi: 10.1136/thoraxjnl-2012-201962 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref011] 11.Judson MA, Baughman RP, Teirstein AS et al. Defining organ involvement in sarcoidosis: the ACCESS proposed instrument. ACCESS Research Group. A Case Control Etiologic Study of Sarcoidosis. Sarcoidosis Vasc Diffuse Lung Dis 1999; 16:75–86. [PubMed] [Google Scholar]

[pone.0273126.ref012] 12.Miller MR, Hankinson J, Brusasco V, et al. Standardisation of spiromerty. ATS/ERS Task Force: Standardization of Lung Function Testing. Eur Respir J 2005; 26:319–338. [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref013] 13.Sintonen H, Pekurinen M. A fifteen-dimensional measure of health-related quality of life (15D) and its applications. In: Walker SR, Rosser R, editors. Quality of life assessment: key issues in 1990s. Dordrecht: Kluwer Academic Publishers; 1993. p. 185–95. [Google Scholar]

[pone.0273126.ref014] 14.Jones PW, Quirk FH, Baveystock CM, et al. A self-complete measure of health status for chronic airflow limitation. The St George’s respiratory questionnaire. Am Rev Respir Dis 1992; 145:1321–7. [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref015] 15.Sintonen H. The 15D-measure of health-related quality of life: I: reliability, validity and sensitivity of its health state descriptive system: working paper 41. Melbourne, Australia: National Centre for Health Program Evaluation; 1994. [Google Scholar]

[pone.0273126.ref016] 16.Sintonen H. The 15D-measure of health-related quality of life II: feasibility, reliability and validity of its valuation system: working paper 42. Melbourne, Australia: National Centre for Health Program Evaluation; 1994. [Google Scholar]

[pone.0273126.ref017] 17.Chang JA, Curtis J. R, Patrick DL, Ragh G. Assessment of Health-Related Quality of Life in Patients with Interstitial Lung Disease. CHEST 1999; 116:1175–1182. doi: 10.1378/chest.116.5.1175 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref018] 18.Medical Research Council. Questionnaire on respiratory symptoms: instructions to interviewers. MRC committee on environmental and occupational health. London: MRC; 1986. [Google Scholar]

[pone.0273126.ref019] 19.Stewart AL, Ware JE, Brook RH. Advances in the measurement of functional status: construction of aggregate indexes. Med Care 1981; 19:473–88. doi: 10.1097/00005650-198105000-00001 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref020] 20.Gvozdenovic BS, Mihailovic-Vucinic V, Ilic-Dudvarski A, Zugic V, Judson MA. Differences in symptom severity and health status impairment between. patients with pulmonary and pulmonary plus extrapulmonary sarcoidosis. Respir Med 2008; 102:1636–1642. [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref021] 21.Baughman RP, Nagai S, Balter M, et al. Defining the clinical outcome status (COS) in sarcoidosis: results of WASOG Task Force. Sarcoidosis Vasc Diffuse Lung Dis 2011; 28:56–64. [PubMed] [Google Scholar]

[pone.0273126.ref022] 22.Bentler P., Chou C. Practical Issues in Structural Modeling. Sociological Methods & Research 1987, 16(1), 78–117. 10.1177/0049124187016001004 [DOI] [Google Scholar]

[pone.0273126.ref023] 23.Cox CE, Donohue JF, Brown CD et al. The Sarcoidosis Health Questionnaire: a new measure of health-related quality of life. Am J Respir Crit Care Med 2003; 168:323–9 doi: 10.1164/rccm.200211-1343OC [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref024] 24.Van Manen MJ, Wapenaar M, Strookappe B, et al. Validation of the King’s Sarcoidosis Questionnaire (KSQ) in a Dutch sarcoidosis population. Sarcoidosis Vasc Diffuse Lung Dis. 2016. Mar 29;33(1):75–82. . [PubMed] [Google Scholar]

[pone.0273126.ref025] 25.Farin E, Heyduck K, Frye BC et al. Translation and psychometric properties of the King’s Sarcoidosis Questionnaire (KSQ) in German language. Health Qual Life Outcomes. 2019. Apr 11;17(1):62. doi: 10.1186/s12955-019-1131-z ; PMCID: PMC6460543. [DOI] [PMC free article] [PubMed] [Google Scholar]

[pone.0273126.ref026] 26.McGlothlin AE, Lewis RJ. Minimal clinically important difference: defining what really matters to patients. JAMA 2014; 312:1342–1343. doi: 10.1001/jama.2014.13128 [DOI] [PubMed] [Google Scholar]

[pone.0273126.ref027] 27.Baughman RP, Judson MA, Beaumont JL, Maier LA, Sweiss NJ, Culver DA, et al. Evaluating the minimal clinically important difference of the King’s Sarcoidosis Questionnaire in a multicenter prospective study. Ann Am Thorac Soc 2021; 18:477–485. doi: 10.1513/AnnalsATS.202006-607OC [DOI] [PubMed] [Google Scholar]

PERMALINK

King’s Sarcoidosis Questionnaire (KSQ) – Validation study in Serbian speaking population of sarcoidosis patients

Mihailo Stjepanovic

Violeta Mihailovic-Vucinic

Branislav S Gvozdenovic

Jelena Milin-Lazovic

Slobodan Belic

Natasa Djurdjevic

Nikola Maric

Aleksa Golubovic

Roles

Abstract

Introduction

Objective

Methods

Results

Introduction

Material and methods

Patients

Pulmonary function tests

Questionnaires

Clinical outcome of sarcoidosis

Table 1. Clinical outcome in sarcoidosis patients.

Questionnaire translation process

Doctors’ comments about KSQ:

Statistical analysis

Results

Table 2. Explanatory factor analysis-rotated component matrix.

Table 3. Correlation between the Serbian version of KSQ scores and other questionnaires.

Table 4. Internal reliability for KSQ translated version.

Table 5. Baseline characteristics of the study participants.

Table 6. KSQ scores in patients with different clinical course of sarcoidosis.

Table 7. Clinical outcome status and KSQ.

Table 8. Correlation between lung function parameters, clinical outcome of sarcoidosis and KSQ.

Discussion

Conclusion

Supporting information

Data Availability

Funding Statement

References

Decision Letter 0

Supat Chupradit

Roles

Author response to Decision Letter 0

Decision Letter 1

Supat Chupradit

Roles

Author response to Decision Letter 1

Decision Letter 2

Gernot Zissel

Roles

Author response to Decision Letter 2

Decision Letter 3

Gernot Zissel

Roles

Acceptance letter

Gernot Zissel

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

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