Cross-Cultural Adaptation, Translation and Validation of Kannada Version of the Swallowing Quality of Life Questionnaire (KSWAL-QOL)

Abstract

The swallowing quality of life (SWAL-QOL) questionnaire is a commonly used tool to assess the impact of dysphagia on quality of life. SWAL-QOL has been translated and validated in many languages. There is no valid dysphagia-specific quality of life tool in Indian languages. Hence, the current study aimed at cultural adaptation, translation, and validation of SWAL-QOL in Kannada (KSWAL-QOL), a south Indian Dravidian language. The original SWAL-QOL was translated into Kannada using the standard translation procedure. A group of 55 participants with oro-pharyngeal dysphagia (clinical group) and 55 participants with normal swallowing abilities (control group) were recruited for the current study to assess the validity and reliability of KSWAL-QOL. Dysphagia Handicap Index- Kannada version (DHI-K) and Life Satisfaction Questionnaire (LISAT) were used to check for the convergent validity of the KSWAL-QOL. The KSWAL-QOL demonstrated excellent discriminant validity and distinguished clinical from the control group across all domains (p = 0.00). Internal consistency for all the nine domains of KSWAL-QOL measured using Cronbach’s α ranged from 0.89 to 0.92, demonstrating excellent reliability. Test-retest measures were exceptional, with Intraclass Correlation Coefficient (ICC) ranging between 0.92 and 0.98 and Spearman’s rho values between 0.91 and 0.97. A very strong negative correlation was obtained between KSWAL-QOL and DHI-K, and a strong positive correlation was seen between KSWAL-QOL and LISAT. The KSWAL-QOL is a reliable and valid tool with excellent psychometric properties to evaluate the quality of life associated with swallowing in individuals with oropharyngeal dysphagia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-04162-w.

Introduction

Health-related quality of life (HRQOL) reflects the impact of health status on an individual’s life. Dysphagia is a health-related concern often connected with a poor quality of life [1–3] due to its adverse effect on emotional, physical, functional, social, financial, and spiritual well-being. Persons with dysphagia often exhibit difficulty in containing and preparing a bolus, propulsion of bolus to the back of the tongue, initiating a swallow, clearing residue after a swallow, etc. [4]. The food or liquid may enter the nasal passage or the airway, leading to several complications. The swallowing problems may make eating difficult for these individuals in public settings like restaurants and social gatherings, negatively affecting their quality of life. They may go through emotional and social changes and experience rage, anxiety, sadness, and social isolation.

In therapeutic settings, there is growing interest in measuring patients’ quality of life (QOL). According to Wenger et al. [5], QOL is “an individual’s perceptions of his or her functioning and well-being in different domains of life”. Various self-report tools are constructed to evaluate patients’ health-related quality of life with reported dysphagia. Some of the tools are Swallowing Quality of life, (SWAL-QOL) [6], MD Anderson Dysphagia Inventory (MDADI) [7], Deglutition Handicap Index (DHI) [8], Dysphagia Handicap Index (DyHI) [9], and Eating Assessment Tool-10 (EAT-10) [10]. Among these, the SWAL-QOL tool addresses all WHO-ICF domains and is widely regarded as the gold standard tool [10–14]. The other tools assess only certain aspects of swallowing and hence fail to address the overall ICF domains of swallowing [15].

SWAL-QOL consists of 44 items covering the major WHO-ICF domains related to the overall health condition, body function and structure, and activity and participation. These items are divided into nine domains: general burden, food selection, eating duration and desire, fear of eating, sleep, fatigue, communication, mental health, and social functioning. Each item is graded on a 5-point Likert scale, with patients receiving specific instructions depending on the assessment areas. Each item is equally weighted and added to obtain an overall score, with a lower score indicating a poor quality of life and a higher score representing an optimal QOL [6]. SWAL-QOL shows the most robust combination of reliability and validity compared to the other existing QOL tools for swallow function and hence can be used in clinical practice to understand the current status of the patient and the effects of the treatment given [15].

Globally, SWAL-QOL has been widely used in research and clinical settings and has been translated and validated in Chinese [16], Dutch [11], Persian [14], Arabic [17], German [18], Norwegian [19], French [20], Swedish [12], Italian [13] and Brazilian Portuguese [21] with excellent psychometric properties specific to individuals with dysphagia with heterogeneous etiologies.

The incidence of dysphagia in India is high. A recent systematic review by Krishnamurthy et al. [22] outlines the incidence of dysphagia in India. According to the authors, the cumulative incidence of dysphagia in the stroke population alone is 47.71% (95% CI [20.49%, 70.92%], p = 0.001). The rise in the incidence calls for early identification and management of dysphagia and addresses the negative impact of dysphagia on quality of life. SWAL-QOL is one such Patient-Reported Outcome Measure (PROM), which aids in recording the patient’s quality of life and helps clinicians to incorporate its findings in prioritizing their needs during management. To date, SWAL-QOL has not been translated into any Indian language. Hence, there is a need to translate and validate the dysphagia-specific QOL in the native language of Karnataka, India, i.e., Kannada, for its widespread clinical use. Though there are tools such as Eating Assessment Tool-10 (EAT-K) [23] and Dysphagia Handicap Index (DHI-K) [24] validated in the Kannada language, these do not provide information on ICF related quality of life domains related to swallowing.

The consequence of dysphagia on an individual’s life identifies no geographical boundary, however dysphagia specific concerns and its impact across the life domains can be culture specific. Further, the swallow rehabilitation in India, specifically in Karnataka and the role that a Speech-Language Pathologists (SLPs) plays is gaining wide publicity and acceptance. There are many Institutes/hospitals that involve in conducting courses and training programs to improve the skill of SLPs as a swallow specialist. Many public awareness activities emphasizing the role of SLPs in handling patients with dysphagia are also being conducted among other health professionals, which has led to increased patient referrals to SLPs. Hence, it is necessary to equip the SLPs with appropriate regional tools. Kannada is a Dravidian language from South India spoken by 59 million people in India and is regarded as one of the classical languages of Karnataka [25]. Keeping this in mind, the current study was undertaken to adapt, translate and validate the original version of SWAL-QOL to Kannada (KSWAL-QOL) and examine its discriminant validity, internal consistency, convergent validity, and test-retest reliability.

Method

The study was conducted in two phases. Phase I involved the adaptation and translation of SWAL-QOL in Kannada. Psychometric properties, including validity, internal consistency, construct validity, and test-retest reliability, were assessed in Phase II.

Phase I: Adaptation and Translation of SWAL-QOL in Kannada

Written permission was obtained from the original author of SWAL-QOL for adapting to the Indian context and translating it into the Kannada language. The section on liquid/food consistency and texture was modified to accommodate the cuisine, culture and lifestyle of South India. The translators were assigned the task of matching the food items in SWAL-QOL with those accessible in South Indian cuisine (while maintaining a similar food texture and consistency). The items in the other nine domains and instructions were retained. The SWAL-QOL adaption was translated into Kannada in accordance with the International Society for Pharmacoeconomics and Outcome Research Task Force’s translation and cultural adaptation requirements [26]. The original version of SWAL-QOL was given for forward translation to Kannada to five proficient translators. Translation experts were told to aim for a term or phrase’s conceptual equivalent rather than a literal translation. They were instructed to focus on the meaning of the original term/phrase and try to translate it in the most admissible manner. All the translated versions were checked for appropriateness of language and ease of understanding by the authors. A single translated version was created by compiling all the versions.

Two Kannada-English bilingual experts, blinded to the original version, back-translated the Kannada version of SWAL-QOL to the English version using a standard parallel back-translation procedure [27]. The first and the third authors compared the back translation with the forward translated version for any discrepancies. The necessary corrections were made in the SWAL-QOL Kannada version. The final version was examined by an expert committee consisting of two Speech-Language Pathologists and a linguist, focusing on achieving semantic, conceptual, and cultural equivalency. The developed KSWAL-QOL was pilot tested on ten individuals reporting oro-pharyngeal dysphagia for its content familiarity and ease of understanding. Thus, KSWAL-QOL was developed. The KSWAL-QOL is given in the Appendix.

Phase II: Assessment of Psychometric Properties

Study Design

A cross-sectional, non-randomized convenience sampling was utilized for the current study.

Participants

For the current study, a total of 110 participants between 20 and 80 years were recruited. Group 1 (clinical group) comprised of 55 participants (male = 40, female = 15; mean age: 52.92yrs ± 16.16yrs) with dysphagia, diagnosed using clinical swallow examination by experienced Speech-Language Pathologist in the field of swallowing (> 5yrs of experience). Clinical group diagnosed with dysphagia were recruited from the centre for swallowing disorders. Group 2 consisted of 55 neurotypicals, age matched (male = 37, female = 18; mean age: 49.70yrs ± 15.54yrs), who served as the control group. All the participants were fluent speakers of the Kannada language. The clinical group included those with a history of head and neck cancer, traumatic brain injury, cerebrovascular accidents, radiation/chemotherapy therapy, and structural alterations of the oropharynx and larynx. The participants in the control group had no history of dysphagia, cerebrovascular accidents, cognitive impairment, head and neck cancer, chemoradiation, or structural modification of oropharyngeal structures. Participants of both groups did not present with any visual or hearing difficulties, which were informally screened during the selection process. The participant characteristics for the clinical group are provided below (Table 1).

Table 1.

Participant characteristics of clinical group

Characteristics	Number	Percentage
Age in years
20–30	05	9.1
31–40	10	18.18
41–50	10	18.18
51–60	10	18.18
> 60	20	36.36
Gender
Male	40	72.7
Female	15	27.3
Etiology*
CVA	31	56.4
TBI	7	12.7
PD	5	9.1
HNC	5	9.1
Others	7	12.7
Mode of food intake
Oral	47	85.5
Non-oral	08	14.5

*CVA: Cerebrovascular Accidents; TBI: Traumatic Brain Injury; PD: Parkinson’s Disease; HNC: Head and Neck Cancer

Administration of the Tool

The purpose of the study and other details were clearly explained to all the participants and their caregivers. The study followed the “Ethical Guidelines of Bio-Behavioral Research Involving Human Subjects” and was approved by the Ethical Committee of the Institute (No.DOR.9.1/Ph. D/BC/920/2021-2022 dated 10th February, 2023 [28]. Before the commencement of the study, informed consent was obtained from all the participants. The data was collected at the centre for swallowing disorders during their visit for detailed evaluation. Participants fulfilling the inclusion criteria filled out the 44-item KSWAL-QOL questionnaire and rated each domain of quality of life using a five-point Likert scale where, a rating of 1 indicated a severe problem and 5 indicated no problem. The obtained score of each domain was totalled and divided by the number of domains to receive a total score ranging from ‘0-100’. The caregiver/researcher assisted the participants without formal education by reading the questions and noting their responses. All participants could complete the survey in 10–15 min.

To measure the test-retest reliability, 20% of the participants responded to the same questionnaire after a gap of two weeks. This time frame was chosen to avoid the recall of previous responses. To test the convergent validity, all the participants (n = 55) filled out the Life Satisfaction Questionnaire (LISAT) [29], while 26 participants filled out the Dysphagia Handicap Index-K (DHI-K) [24]. The life satisfaction questionnaire is a simple nine-item scale in Kannada to assess general life satisfaction in terms of daily activity, profession, sex life, family life, etc. It is a 6-point Likert scale where 1 indicated extremely unsatisfied to 6 indicating extreme satisfaction. DHI-K is a 25-item questionnaire subdivided into physical, functional, and emotional dimensions to measure the quality of life in persons with dysphagia. Each item is scored as 0-never, 2-sometimes, and 4-always, with a total score ranging between 0 and 100. Higher scores on LISAT and DHI-K indicate poor life satisfaction and severe swallow impairment, respectively. DHI-K and LISAT were chosen to analyze convergent validity as the two questionnaires were standardized and made available in the Kannada language.

Statistical Analyses

The obtained raw scores were tabulated and subjected to statistical analyses using IBM SPSS version 26. The descriptive statistics for the data were obtained. Cronbach’s alpha was used to assess the internal consistency of the questionnaire. The normality of samples was tested using the Shapiro-Wilks test. A non-normal distribution of the data was observed. Hence, the Mann-Whitney U test was employed to distinguish clinical versus control group on their performance over KSWAL-QOL. Convergent validity and test-retest reliability were computed using Spearman’s correlation coefficient and Intraclass correlation coefficient (ICC).

Results

The descriptive statistics, including median, interquartile range, and difference /Z/ values (discriminant validity measures), for groups (clinical and control) are shown in Table 2. The control group obtained higher median values in all domains. The median of the clinical group ranged from 60 to 70. The results of the Mann-Whitney U test also revealed a significant difference (p < 0.001) between groups (clinical and control) across all the nine domains, which indicated that KSWAL-QOL had good discriminant validity. The effect size (r) was calculated for the overall SWAL-QOL score, which showed a high effect size (0.8). The median scores across KSWAL-QOL domains of the clinical and control group have been depicted in Fig. 1.

Table 2.

Descriptive statistics and results of discriminant validity measures of clinical and control group across all domains of KSWAL-QOL

KSWAL-QOL Domains	No. of items	Clinical Group		Control Group		Difference /Z/ value	P value (two-tailed)
		Median	IQR	Median	IQR
Eating Burden	02	60.0	40.0	100	0.0	9.14	0.00*
Eating Desire and Duration	05	64.0	36.0	100	0.0	9.34	0.00*
Symptom frequency	14	67.20	18.54	100	2.90	9.04	0.00*
Food selection	02	60.0	20.0	100	0.0	8.49	0.00*
Communication	02	70.0	30.0	100	0.01	8.22	0.00*
Fear	05	65.0	25.0	100	0.01	8.58	0.00*
Mental health	04	68.0	32.0	100	0.0	9.25	0.00*
Social functioning	05	60.0	32.0	100	0.0	9.12	0.00*
Fatigue and sleep	05	64.0	20.0	100	0.0	8.96	0.00*
SWAL-QOL Overall score	44	65.0	20.14	100	0.33	9.14	0.00*

*IQR: Inter Quartile Range; p value statistically significant at level 0.001 (2-tailed); Effect size (r)= , |Z|- Z score, N=Total observations, r < 0.3 denotes low effect size, r= 0.3 to 0.5 denotes medium effect size, r = > 0.5 indicates high effect size

Fig. 1.

Median scores across KSWAL-QOL domains of clinical and control groups

Internal Consistency

The way an instrument’s items measure different facets of the same attribute or concept is reflected in its internal consistency. Internal consistency for all the domains of KSWAL-QOL was measured using Cronbach’s alpha. The values range from 0 (no internal consistency) to 1 (perfect internal consistency). As shown in Table 3, reliability values of KSWAL-QOL ranged from 0.89 to 0.93, indicating excellent internal consistency. The results revealed that the domains of KSWAL-QOL are analogous and measure the same construct.

Table 3.

Reliability measures across all domains of KSWAL-QOL

Domain	Internal Consistency Cronbach’s α	Test-retest (n = 11)
		Spearman’s ρ	ICC
Eating Burden	0.89	0.91	0.98
Eating Desire and Duration	0.90	0.95	0.98
Symptom frequency	0.90	0.95	0.97
Food selection	0.90	1.00	0.98
Communication	0.93	0.97	0.98
Fear	0.91	0.97	0.96
Mental health	0.89	0.75	0.92
Social functioning	0.90	0.93	0.98
Fatigue and sleep	0.90	0.96	0.97

Test-Retest Reliability

Twenty percent of the data (n = 11) from the clinical group was used for calculating test-retest reliability. Spearman’s rank correlation coefficient and Intraclass correlation coefficient (ICC- two-way mixed effect model, type-single measurement and definition-absolute agreement) were used to calculate the reliability. Spearman’s ρ for all the domains except food selection and mental health ranged between 0.91 and 0.97, indicating very strong reliability. A monotonic correlation (1.00) was seen for food selection, and strong reliability was seen for the mental health domain. ICC values ranged between 0.92 and 0.98, indicating excellent test-retest reliability.

Convergent Validity

To test convergent validity, domains common to KSWAL-QOL and DHI-K were compared. In addition, the overall scores of KSWAL-QOL were compared with LISAT using Spearman’s correlation. A strong negative correlation was obtained for the selected domains of KSWAL-QOL with the functional, physical, and emotional domains of DHI-K (Table 4). The overall score of KSWAL-QOL exhibited a very strong negative correlation with the overall score of DHI-K and a strong positive correlation with the overall score of LISAT.

Table 4.

Correlation between KSWAL-QOL, DHI-K, and LISAT

Domains	Spearman’s ρ	P value
Eating desire, duration and food selection versus DHI-K functional domain	-0.580	0.001*
Symptom frequency versus DHI-K physical domain	-0.662	0.001*
Mental health and social functioning versus DHI-K emotional domain	-0.585	0.001*
Overall swallowing quality of life versus DHI-K	-0.858	0.00*
Overall swallowing quality of life versus Life Satisfaction Questionnaire	0.736	0.001*

*p value statistically significant at level 0.001 (2-tailed)

Discussion

The use of self-report tools to capture the patient’s perspective is one of the critical elements of a thorough evaluation approach for dysphagia. SWAL-QOL is one such promising tool for evaluating QOL in patients with dysphagia. Internationally, SWAL-QOL is translated into many languages, but thus far it has not been translated into any Indian language. The current study aimed to adapt, translate, and validate KSWAL-QOL and to check for its psychometric properties. The tool was translated and validated using a standard procedure [26, 27]. The KSWAL-QOL questionnaire was well-received, well-understood, and scored by all participants, demonstrating its acceptability and viability. The results are consistent with the research from the English, Swedish and Persian versions [6, 12, 14].

The discriminant validity measurement (shown in Table 2) revealed that KSWAL-QOL had excellent validity in differentiating participants with normal swallow functions from participants with dysphagia. The clinical group obtained a lower median score on all domains of KSWAL-QOL, indicating compromised swallow quality of life across different domains of KSWAL-QOL. The current tool also receives additional clinical validation as a PROM in distinguishing between participants with oro-pharyngeal dysphagia and healthy controls. The tool also receives a high effect size (0.8). The results are congruent with the initial SWAL-QOL English version, Arabic, German, Norwegian, and Greek versions [6, 16–19, 30].

Reliability estimates were measured using Cronbach’s α, Spearman’s ρ, and ICC. Internal consistency of all domains showed α value ranging from 0.89 to 0.93, indicating excellent internal consistency. The results indicate that each item of the domain is uniform and evaluates various aspects of similar traits. These results were in agreement with those of the original English, Swedish, Persian, and German versions of SWAL-QOL [6, 12, 14, 18]. Spearman’s correlation coefficient and the intraclass correlation coefficient were used to confirm the test-retest reliability. KSWAL-QOL demonstrated a strong to very strong correlation across all domains, indicating the stability of scores between the two measurements. These results concur with the original English, Swedish, Chinese, and Arabic versions of SWAL-QOL [5, 11, 16, 17].

The convergent validity of KSWAL-QOL was ascertained using DHI-K and LISAT. DHI-K is a well-known tool to measure swallow handicap, and the latter is used to measure overall satisfaction. A strong negative correlation was obtained on selected KSWAL- QOL and DHI-K domains and a strong positive correlation between KSWAL- QOL and LISAT. The negative correlation between SWAL-QOL and DHI-K was because of the difference in the scoring pattern of the two tools. Ideally, participants obtaining maximum scores in SWAL-QOL will tend to have low scores on DHI-K and vice versa. Hence, the results are justified with a strong negative correlation. The findings are in consonance with the Arabic version of SWAL-QOL, except that the current study used DHI-K and LISAT for analyzing validity [17].

The current study comes with certain limitations. Recruitment of participants with dysphagia was merely done based on subjective evaluation using clinical protocols; no instrumental assessments such as Fiberoptic Endoscopy/Videofluoroscopy were performed to confirm the same. Future studies are essential in correlating the KSWAL-QOL with objective procedures such as Fiberoptic Endoscopy/Videofluoroscopy, considering the disease severity and duration of disease onset. The study also fails to account for an equal number of individuals responding to the DHI-K and LISAT questionnaires. McHorney et al. [6] and Finizia et al. [12] reported that tube-fed patients frequently report having trouble responding to specific questions from the SWAL-QOL because they do not believe the inquiries are pertinent to their situation. This trend was also seen in the current study, which had 14.5% of tube feeders. Thus, it was seen that all questions on the tool applied to oral feeders, while a few of the questions did not apply to tube feeders. Therefore, a different set of questions might have to be included to examine the quality of life in tube feeders, which can be taken up as a future research initiative. Future studies could also test the efficacy of KSWAL-QOL in evaluating the quality of life before and after swallow therapy across various disease conditions and severity.

Conclusion

The current study is the first to adapt, translate and validate the SWAL-QOL in the Indian context. The study demonstrated that KSWAL-QOL is a reliable and valid tool to assess the quality of life in Kannada-speaking individuals with dysphagia. The tool illustrates good validity in discriminating individuals with clinically normal swallow abilities from those with dysphagia. It has shown excellent psychometric properties in construct validity, test-retest reliability, and convergent validity. It can be used as an outcome measure to track the improvement in terms of swallow quality of life in Kannada-speaking individuals with dysphagia.

Electronic Supplementary Material

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Authors’ contributions

BC and SN: conceptualizing and designing of the research study, seeking ethical approval, drafting the manuscript in whole or in part; BC and SB: data collection; BC: analyzing the data: All the authors approved the final manuscript.

Data Availability

All data generated or analyzed during this study are included in the article. Further enquiries can be directed to the corresponding author.

Declarations

Ethical approval and consent to participate

Participant/guardians had given their written informed consent. The ethical clearance according to the Declaration of Helsinki was obtained from the Institutional Review Board, AIISH Ethics committee (AEC), Approval number: No.DOR.9.1/Ph. D/BC/920/2021–2022 dated 10th February, 2023.

Conflict of Interest

There are no conflicts of interest to declare.

Financial Support and Sponsorship

There are no funding sources to declare.