Abstract
The Wound‐QoL assesses the impact of chronic wounds on patients' health‐related quality of life (HRQoL). A 17‐item and a shortened 14‐item version are available. The Wound‐QoL‐17 has been validated for multiple languages. For the Wound‐QoL‐14, psychometric properties beyond internal consistency were lacking. We aimed to validate both Wound‐QoL versions for international samples representing a broad range of European countries, including countries for which validation data had yet been pending. Patients with chronic wounds of any aetiology or location were recruited in Austria, Lithuania, the Netherlands, Poland, Slovakia, Spain, Switzerland and Ukraine. Psychometric properties were determined for both Wound‐QoL versions for the overall sample and, if feasible, country‐wise. We included 305 patients (age 68.5 years; 52.8% males). Internal consistency was high in both Wound‐QoL‐17 (Cronbach's α: 0.820–0.933) and Wound‐QoL‐14 (0.779–0.925). Test–retest reliability was moderate to good (intraclass correlation coefficient: 0.618–0.808). For Wound‐QoL‐17 and Wound‐QoL‐14, convergent validity analyses showed highest correlations with global HRQoL rating (r = 0.765; r = 0.751) and DLQI total score (r = 0.684; r = 0.681). Regarding clinical data, correlations were largest with odour (r = −0.371; r = −0.388) and wound size (r = 0.381; r = 0.383). Country‐wise results were similar. Both Wound‐QoL versions are valid to assess HRQoL of patients with chronic wounds. Due to its psychometric properties and brevity, the Wound‐QoL‐14 might be preferrable in clinical practice where time is rare. The availability of various language versions allows for the use of this questionnaire in international studies and in clinical practice when foreign language patients are being treated.
Keywords: outcomes research, quality of life, ulcer
1. INTRODUCTION
Chronic wounds are characterised by insufficient healing in a timely manner 1 and/or by being caused by an underlying condition. 2 , 3 A systematic review revealed a total prevalence of chronic wounds 1.67 per 1000 people. 4 Prevalence rates are higher in people above the age of 65 years, 5 which presents a challenge particularly in the European ageing society. In addition to the economic burden of chronic wounds on societal level, 5 treatment is often complex and time‐consuming for the individual patient 6 and burdensome for caregivers. 7 , 8 Many patients are strained by long‐lasting comorbidity 9 and marked loss of health‐related quality of life (HRQoL). 5
Patients experience HRQoL impairments on various levels: Besides physical wound‐specific burden, such as exudate, odour and wound pain, the condition can cause psychological strain, which can lead to sleep disturbances, anxiety and depression. 10 Living with chronic wounds can impact the financial status of patients 11 and cause considerable restrictions in everyday activities 11 as well as social participation. 12
To assess the impact of chronic wounds on all these dimensions, wound‐specific HRQoL questionnaires can be used. They allow for treatment planning, evaluation and patient–physician communication. To increase feasibility in both routine care and research, these questionnaires need to be short and easy to use.
Therefore, we have developed the Wound‐QoL questionnaire; currently, two versions are available. The original Wound‐QoL with 17 items (Wound‐QoL‐17) was established in 2014. 11 Recently, a shortened 14‐item version (Wound‐QoL‐14) was developed, in which three items of the Wound‐QoL‐17 are omitted due to statistical and contextual considerations. 13 In both versions, items are answered on a 5‐point Likert scale ranging from ‘not at all’ to ‘very’. From these, a global score and three subscale scores (body, psyche, everyday life) can be calculated (mean scores; range: 0–4). The subscales are calculated from five (body, psyche) to six (everyday life) items in the Wound‐QoL‐17 and from four (body, psyche) to five (everyday life) items in the Wound‐QoL‐14. In each version, one item is not used for subscale calculation (Wound‐QoL‐17: item on financial burden; Wound‐QoL‐14: item on treatment burden).
Both Wound‐QoL versions are available in numerous languages. For several languages, validation data of the Wound‐QoL‐17 exist. 11 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 For the Wound‐QoL‐14, we could confirm internal consistency and cross‐cultural metric invariance 13 ; the analysis of further psychometric properties was still lacking.
With the current study, we aim to provide validation data for both Wound‐QoL versions for international samples representing a broad range of European countries, including a range of countries for which validation data had been lacking, yet.
2. METHODS
2.1. Ethics
The local Ethics Committee of the Medical Association of Hamburg (Ethikkommission der Ärztekammer Hamburg) approved this study in June 2019 (PV7029). Secondary ethic votes were obtained from local ethic committees in the participating countries.
2.2. Participants
This study aimed to enrol patients with chronic wounds treated in outpatient dermatological clinics in 10 European countries. Two project partners (France, Italy) were not able to continue participation prior to start of recruitment, resulting in eight participating countries (Austria, Lithuania, the Netherlands, Poland, Slovakia, Spain, Switzerland, Ukraine). Each study centre aimed at recruiting 50 patients. Inclusion criteria were a minimum age of 18 years, diagnosis of chronic wound(s) and ability to understand and complete the questionnaire.
2.3. Procedure
Patients with chronic wounds were recruited during their regular visit in one of the participating study centres. Participants received written information, and informed consent was obtained. They completed a paper‐based questionnaire including questions on sociodemographic characteristics, questions on wound characteristics and patient‐reported outcome measurements (PROMs). Additionally, participants received the Wound‐QoL as stand‐alone questionnaire and were instructed to complete this questionnaire 7 days after their visit. Healthcare professionals completed the clinical questionnaire assessing wound characteristics.
2.4. Measures
Patients answered the following PROMs:
Wound‐QoL (patients completed the 17‐item version; from this, we also calculated the 14 version).
Dermatology Life Quality Index (DLQI 23 ) on dermatology‐specific HRQoL: 10 items; 4‐point Likert scale; global scale range: 0–30; subscales: symptoms and feeling, daily activities, leisure subscale, work and school, personal relationships, treatment (range: either 0–3 or 0–6).
EQ‐5D‐5L 24 on generic HRQoL: 5 items; five‐level response options; country‐specific value sets; for the present study, value sets from two participating countries were used representing Central/Eastern and Western European countries: Poland (range: −0.590–1 25 ) and Spain (range: −0.501–1 26 ).
EQ VAS on subjective health: one‐page numeric visual analogue scale; range: 0–100.
Global rating on HRQoL: single item; 5‐point Likert scale; range: 1–5.
Numeric rating scale (NRS) on pain at dressing change: single item; 11‐point rating scale; range: 0–10.
NRS on pain at rest: single item; 11‐point rating scale; range: 0–10.
Wound type and duration (in months) were assessed in both patient and clinical questionnaires.
The clinical questionnaire assessed the following wound characteristics:
Wound slough (multiple choice [MC]): none, necrosis, fibrin; in analyses none vs. present).
Wound edge (MC): not irritated, flushed/reddened, oedematous, macerated, livid, necrotic, hyperkeratotic, undermined; in analyses: not irritated vs. irritated).
Wound environment (MC: not irritated, reddened, oedematous, macerated, moist, scaly/flaky, erosive; in analyses: not irritated vs. irritated).
Odour (none, present).
Amount of exudate (none, little, medium, severe).
Wound size (in cm2).
2.5. Statistical analysis
Sample characteristics and distribution of the questionnaire items and scores were analysed using descriptive statistics, depending on the scale level. For validation analysis, we calculated for global and subscale scores of Wound‐QoL‐17 and Wound‐QoL‐14: floor and ceiling effect (percentage of patients with lowest and highest possible score); internal consistency (Cronbach's α); item selectivity (correlation of global score with items and subscale scores and correlation of subscale scores with items; Spearman correlation); convergent validity (correlation of global and subscale scores with other measurements; Spearman correlation for continuous, Mann–Whitney U test for dichotomous or Kruskal–Wallis test for ordinal variables); and test–retest reliability (intraclass correlation [ICC]; two‐way mixed, absolute agreement; when retest was completed 5–9 days later). For convergent validity testing, hypotheses were developed prior to analysis based on previously published data (Appendix S1).
Cronbach's α was considered good when between 0.70 and 0.95. 27 Effect sizes were considered small when r > 0.10 or η2 > 0.01, medium when r > 0.30 or η2 > 0.06 and large when r > 0.50 or η2 > 0.14. 28 ICC was rated moderate when >0.50, good when ICC >0.75 and excellent when ICC >0.90. 29
All analyses were conducted using SPSS v. 27.0 (IBM, Armonk, NY, USA). Analyses were conducted for the European sample and country‐wise for those countries having collected data for at least n = 30 patients.
3. RESULTS
In the following, results for the European sample are reported. Country‐specific results are shortly reported at the end of this section and displayed in detail in the Appendix S1.
3.1. Sample characteristics
The sample (Tables 1, 2, 3, 4) consisted of 305 participants of which 221 (72.4%) sent back the retest questionnaire. Mean age was 68.5 years (SD: 13.9, range: 28–96), and 52.8% (n = 161) were male. As reported in the clinical questionnaire, the most frequent wound types were venous leg ulcers (n = 101, 33.1%), followed by diabetic foot ulcer (n = 76, 24.9%) and other wounds (n = 75, 24.6%; e.g. oncological wounds, post‐surgical wounds, nonhealing wound after amputation). Mean wound duration was 20.0 months (SD: 54.4, median: 6.0 range: 0–600).
TABLE 1.
Characteristics of the total group of study participants with chronic wounds (N = 305 patients in eight countries).
| Variable | Response options | n | % |
|---|---|---|---|
| Gender | Male | 161 | 52.8 |
| Female | 143 | 46.9 | |
| Missing values | 1 | 0.3 | |
| Highest educational level | No certificate | 7 | 2.3 |
| Certificate without university entrance | 161 | 52.8 | |
| Certificate with university entrance | 108 | 35.4 | |
| Other | 22 | 7.2 | |
| Missing values | 7 | 2.3 | |
| Occupational status | Full‐/part‐time job | 41 | 13.4 |
| Leave | 4 | 1.3 | |
| House | 24 | 7.9 | |
| Retired | 200 | 65.6 | |
| Early | 23 | 7.5 | |
| Unemployed | 17 | 5.6 | |
| Training | 1 | 0.3 | |
| Missing values | 5 | 1.7 | |
| Family status | Single | 28 | 9.2 |
| Permanent relationship | 15 | 4.9 | |
| Married | 145 | 47.5 | |
| Living separately | 1 | 0.3 | |
| Divorced | 29 | 9.5 | |
| Widowed | 86 | 28.2 | |
| Missing values | 1 | 0.3 | |
| Having children | Yes | 247 | 81.0 |
| No | 56 | 18.4 | |
| Missing values | 2 | 0.7 | |
| Living situation (multiple responses possible) | Alone | 104 | 34.1 |
| With partner | 145 | 47.5 | |
| With children | 65 | 21.3 | |
| With other | 19 | 6.2 | |
| Missing values | 2 | 0.7 | |
| Living in a nursing home | Yes | 25 | 8.2 |
| No | 274 | 91.1 | |
| Missing values | 2 | 0.7 |
| Variable | n | Mean | SD | Median | Range |
|---|---|---|---|---|---|
| Age (years) | 302 | 68.5 | 13.9 | 70.0 | 28.0; 96.0 |
| Working hours/week | 36 | 36.7 | 12.1 | 40.0 | 8.0; 60.0 |
| Number of children | 294 | 1.8 | 1.4 | 2.0 | 0.0; 11.0 |
Abbreviations: n, number of participants; SD, standard deviation.
TABLE 2.
Descriptive analysis of patient‐reported outcomes of N = 305 patients.
| Variable | n | Mean | SD | Median | Range | |
|---|---|---|---|---|---|---|
| Global HRQoL rating | 292 | 3.5 | 1.2 | 4.0 | 1.0; 5.0 | |
| NRS at dressing change | 302 | 4.3 | 3.1 | 4.8 | 0.0; 10.0 | |
| NRS at rest | 302 | 3.4 | 2.8 | 3.0 | 0.0; 10.0 | |
| EQ‐5D‐5L | Polish value set | 294 | 0.7 | 0.3 | 0.8 | −0.6; 1.0 |
| Spanish value set | 294 | 0.5 | 0.3 | 0.6 | −0.4; 1.0 | |
| EQ VAS | 298 | 55.4 | 19.9 | 50.0 | 0.0; 100.0 | |
| DLQI | Total score | 297 | 10.2 | 6.6 | 9.0 | 0.0; 28.0 |
| Symptoms and feelings | 300 | 2.8 | 1.7 | 3.0 | 0.0; 6.0 | |
| Daily activities | 293 | 2.4 | 1.9 | 2.0 | 0.0; 6.0 | |
| Leisure | 292 | 2.1 | 2.0 | 2.0 | 0.0; 6.0 | |
| Work and school | 296 | 0.8 | 1.3 | 0.0 | 0.0; 0.3 | |
| Personal relationships | 299 | 1.0 | 1.5 | 0.0 | 0.0; 6.0 | |
| Treatment | 303 | 1.1 | 1.0 | 1.0 | 0.0; 3.0 | |
Abbreviations: DLQI, Dermatology Life Quality Index; EQ VAS, visual analogue scale of the EQ‐5D instrument; EQ‐5D‐5L, 5‐level EQ‐5D; HRQoL, health‐related quality of life; n, number of participants; NRS, numeric rating scale; SD, standard deviation.
TABLE 3.
Wound type of N = 305 patients according to patient and clinician reports (multiple responses possible).
| Patient‐reported | Clinician‐reported | ||||
|---|---|---|---|---|---|
| Wound type | n | % | Wound type | n | % |
| Venous ulcer | 70 | 23.0 | Ulcus cruris venosum | 101 | 33.1 |
| Arterial ulcer | 24 | 7.9 | Ulcus crusis arteriosum | 21 | 6.9 |
| Mixed ulcer | 25 | 8.2 | Ulcus cruris mixtum | 33 | 10.8 |
| Diabetic foot ulcer | 76 | 24.9 | Diabetic foot ulcer | 76 | 24.9 |
| Decubitus | 18 | 5.9 | Decubitus | 20 | 6.6 |
| Other | 54 | 17.7 | Other | 75 | 24.6 |
| Unknown | 54 | 17.7 | – | – | – |
| Missing values | 5 | 1.6 | Missing values | 8 | 2.6 |
Abbreviation: n, number of participants.
TABLE 4.
Wound characteristics (clinician‐reported if not stated otherwise) of N = 305 patients.
| Variable | n | % | |
|---|---|---|---|
| Wound slough | None | 72 | 23.6 |
| Present | 224 | 75.7 | |
| Missing values | 9 | 3.0 | |
| Wound edge | Irritated | 259 | 84.9 |
| Not irritated | 41 | 13.7 | |
| Missing values | 5 | 1.7 | |
| Wound environment | Irritated | 258 | 84.6 |
| Not irritated | 41 | 13.7 | |
| Missing values | 6 | 2.0 | |
| Odour | None | 200 | 65.6 |
| Present | 100 | 32.8 | |
| Missing values | 5 | 1.7 | |
| Amount of exudate | None | 39 | 12.8 |
| A little | 118 | 38.7 | |
| Medium | 107 | 35.1 | |
| Strong | 32 | 10.5 | |
| Missing values | 9 | 3.0 | |
| Variable | n | Mean | SD | Median | Range |
|---|---|---|---|---|---|
| Wound size (cm2) | 287 | 44.2 | 121.9 | 9.8 | 0.1; 1400.0 |
| Wound duration, patient‐reported (months) | 299 | 24.9 | 63.8 | 6.0 | 0.0; 600.0 |
| Wound duration, clinician‐reported (months) | 279 | 20.0 | 54.4 | 6.0 | 0.0; 600.0 |
Abbreviations: n, number of participants; SD, standard deviation.
3.2. Number of missing values
Two patients (0.7%) did not fill in the Wound‐QoL at all, whereas 273 (89.5%) did not have any missing value. The other patients had between one (n = 18, 5.9%) and six (n = 1, 0.3%) missing items (mean: 0.3; median: 0.0). Of those answering the Wound‐QoL, between none (0.0%) and six (2.0%) patients had missing values per item. Descriptive characteristics of the Wound‐QoL items and scales are displayed in Table 5.
TABLE 5.
Descriptive characteristics of Wound‐QoL items, global scales and subscales of N = 303 patients completing the Wound‐QoL.
| Variable | n | n (%) quite/very+ | Mean | SD | Median | Range | |
|---|---|---|---|---|---|---|---|
| 1 | My wound hurts | 301 | 128 (42.5) | 2.2 | 1.4 | 2.0 | 0.0; 4.0 |
| 2 | My wound had a bad smell | 299 | 41 (13.7) | 1.0 | 1.3 | 0.0 | 0.0; 4.0 |
| 3 | The discharge from the wound has upset me | 299 | 78 (26.1) | 1.6 | 1.3 | 1.0 | 0.0; 4.0 |
| 4 | The wound has affected my sleep | 297 | 110 (37.0) | 1.8 | 1.5 | 2.0 | 0.0; 4.0 |
| 5 | The treatment of the wound has been a burden to me | 301 | 116 (38.5) | 2.0 | 1.4 | 2.0 | 0.0; 4.0 |
| 6 | The wound has made me unhappy | 299 | 113 (37.8) | 1.8 | 1.4 | 2.0 | 0.0; 4.0 |
| 7 | I have felt frustrated because the wound is taking so long to heal | 302 | 161 (53.3) | 2.4 | 1.4 | 3.0 | 0.0; 4.0 |
| 8 | I have worried about my wound | 301 | 174 (57.8) | 2.7 | 1.3 | 3.0 | 0.0; 4.0 |
| 9 | I have been afraid of the wound getting worse or of getting new wounds | 298 | 175 (58.7) | 2.6 | 1.4 | 3.0 | 0.0; 4.0 |
| 10++ | I have been afraid of hitting the wound against something | 300 | 154 (51.3) | 2.3 | 1.4 | 3.0 | 0.0; 4.0 |
| 11 | I have had trouble moving around because of the wound | 299 | 126 (42.1) | 2.0 | 1.4 | 2.0 | 0.0; 4.0 |
| 12++ | Climbing stairs has been difficult because of the wound | 298 | 128 (43.0) | 2.0 | 1.6 | 2.0 | 0.0; 4.0 |
| 13 | I have had trouble with everyday activities | 300 | 134 (44.7) | 2.0 | 1.5 | 2.0 | 0.0; 4.0 |
| 14 | The wound has limited my recreational activities | 301 | 151 (50.2) | 2.2 | 1.6 | 3.0 | 0.0; 4.0 |
| 15 | The wound has forced me to limit my contact with other people | 299 | 106 (35.5) | 1.7 | 1.5 | 2.0 | 0.0; 4.0 |
| 16 | I have felt dependent on help from others because of the wound | 302 | 139 (46.0) | 2.2 | 1.6 | 2.0 | 0.0; 4.0 |
| 17++ | The wound has been a financial burden to me | 303 | 111 (36.6) | 1.8 | 1.5 | 2.0 | 0.0; 4.0 |
| Wound‐QoL‐17 | |||||||
| Global score | 301 | – | 2.0 | 1.0 | 2.0 | 0.0; 4.0 | |
| Body subscale | 300 | – | 1.7 | 1.1 | 1.6 | 0.0; 4.0 | |
| Psyche subscale | 300 | – | 2.4 | 1.1 | 2.4 | 0.0; 4.0 | |
| Everyday life subscale | 299 | – | 2.0 | 1.3 | 2.2 | 0.0; 4.0 | |
| Wound‐QoL‐14 | |||||||
| Global score | 301 | – | 2.0 | 1.0 | 2.1 | 0.0; 4.0 | |
| Body subscale | 301 | – | 1.6 | 1.1 | 1.5 | 0.0; 4.0 | |
| Psyche subscale | 300 | – | 2.4 | 1.2 | 2.5 | 0.0; 4.0 | |
| Everyday life subscale | 300 | – | 2.0 | 1.3 | 2.0 | 0.0; 4.0 | |
Note: +Participants who answered with ‘quite’ or ‘very’. ++Item excluded in Wound‐QoL‐14.
Abbreviations: n, number of participants; SD, standard deviation.
Of the 221 patients with retest data, two did not complete the Wound‐QoL (0.9%), whereas 196 (88.7%) completed all items. The other patients had between one (n = 19, 8.6%) and six (n = 1, 0.5%) missing items (mean: 0.3; median: 0.0). Of those answering the Wound‐QoL, between none (0.0%) and six (2.8%) patients had missing values per item.
3.3. Wound‐QoL‐17
3.3.1. Floor and ceiling effects
In the everyday life subscale, 16 patients (5.3%) achieved the lowest possible score, indicating a small floor effect. In the other (sub)scales, no floor effect was detectable (three (1.0%) to 10 (3.3%) patients with lowest possible score).
In the global scale and the body subscale, no ceiling effect was detectable with three (1.0%) and 10 (3.3%) patients achieving the highest possible score, whereas the psyche (n = 31, 10.2%) and the everyday life subscale (n = 27, 8.9%) did show a ceiling effect.
3.3.2. Internal consistency
Across all scales, internal consistency (Table 6) was high with Cronbach's α ranging from 0.933 (global scale, n = 273) to 0.820 (body subscale, n = 289).
TABLE 6.
Internal consistency of global and subscale scores.
| Wound‐QoL‐17 | Wound‐QoL‐14 | |||||
|---|---|---|---|---|---|---|
| Number of items | n | Cronbach's α | Number of items | n | Cronbach's α | |
| Global score | 17 | 273 | 0.933 | 14 | 276 | 0.925 |
| Body subscale | 5 | 289 | 0.820 | 4 | 289 | 0.779 |
| Psyche subscale | 5 | 292 | 0.863 | 4 | 294 | 0.881 |
| Everyday life subscale | 6 | 292 | 0.927 | 5 | 294 | 0.918 |
Abbreviation: n, number of participants.
3.3.3. Item selectivity
Item selectivity (Appendix S1) ranged from r = 0.524 to r = 0.821 for the global score with highest correlation coefficients in items on everyday activities (r = 0.821), moving around (r = 0.798) and being unhappy (r = 0.787). The lowest correlation coefficients were detected for items on disturbing discharge from the wound (r = 0.524) and wound smell (r = 0.535). Subscale item selectivity ranged from r = 0.636 to r = 0.826 for the body subscale, from r = 0.695 to r = 0.854 for the psyche subscale and from r = 0.796 to r = 0.900 for the everyday life subscale.
3.3.4. Convergent validity
Convergent validity (Table 7) of the Wound‐QoL‐17 regarding other PROMs was high, showing largest effect sizes for global rating scale (r = 0.765, p < 0.001, n = 289), and the DLQI total score (r = 0.684, p < 0.001, n = 294). Correlation with EQ VAS revealed only moderate effect size (r = −0.460, p < 0.001, n = 296).
TABLE 7.
Convergent validity of the Wound‐QoL‐17 and Wound‐QoL‐14.
| Wound‐QoL‐17 | Wound‐QoL‐14 | |||||
|---|---|---|---|---|---|---|
| r | p | n | r | p | n | |
| Continuous and ordinal variables | ||||||
| EQ‐5D‐5L (Polish value set)+ | −0.606 | <0.001 | 291 | −0.600 | <0.001 | 291 |
| EQ‐5D‐5L (Spanish value set)+ | −0.634 | <0.001 | 291 | −0.629 | <0.001 | 291 |
| EQ VAS+ | −0.460 | <0.001 | 296 | −0.473 | <0.001 | 296 |
| DLQI+ | 0.684 | <0.001 | 294 | 0.681 | <0.001 | 294 |
| Global rating+ | 0.765 | <0.001 | 289 | 0.751 | <0.001 | 289 |
| NRS during change+ | 0.531 | <0.001 | 299 | 0.524 | <0.001 | 299 |
| NRS at rest+ | 0.597 | <0.001 | 299 | 0.597 | <0.001 | 299 |
| Wound size | 0.381 | <0.001 | 283 | 0.383 | <0.001 | 283 |
| Duration of wound++ | 0.209 | <0.001 | 275 | 0.195 | 0.001 | 275 |
| Amount of exudate++ | 0.298 | <0.001 | 292 | 0.318 | <0.001 | 292 |
| Dichotomous variables | ||||||
| Wound edge++ | −0.256 | <0.001 | 296 | −0.241 | <0.001 | 296 |
| Wound environment++ | −0.209 | <0.001 | 295 | −0.195 | 0.001 | 295 |
| Wound cover++ | −0.173 | 0.004 | 292 | −0.168 | 0.005 | 292 |
| Odour++ | −0.371 | <0.001 | 296 | −0.388 | <0.001 | 296 |
Note: +Patient‐reported; ++Clinician‐reported.
Abbreviations: DLQI, Dermatology Life Quality Index; EQ VAS, visual analogue scale of the EQ‐5D instrument; EQ‐5D‐5L, 5‐level EQ‐5D; n, number of participants; NRS, numeric rating scale; p, significance value; r, effect size.
Correlation between the body subscale and the DLQI symptoms and feelings subscale (r = 0.618, p < 0.001, n = 296) and with the DLQI treatment subscale (r = 0.467, p < 0.001, n = 299) showed large to medium effect sizes; correlation between the psyche subscale and the DLQI personal relationships subscale (r = 0.374, p < 0.001, n = 295) showed medium effect size; and correlations between the everyday life and the DLQI leisure subscale (r = 0.482, p < 0.001, n = 288) and the DLQI work and school subscale (r = 0.201, p = 0.001, n = 291) showed medium to low effect sizes.
Convergent validity analyses with wound‐specific data showed medium effect sizes regarding wound size (r = 0.381, p < 0.001, n = 283) and odour (r = −0.371, p < 0.001, n = 296). Other clinician‐reported data showed only small, but statistically significant effects.
3.3.5. Test–retest reliability
Test–retest reliability was good for the global scale (ICC = 0.771, 95% confidence interval (CI) 0.666–0.842) and the everyday life subscale (ICC = 0.808, 95% CI = 0.736, 0.861), and moderate for the psyche (ICC = 0.703, 95% CI = 0.584, 0.789) and the body subscales (ICC = 0.622, 95% CI = 0.465, 0.734).
3.4. Wound‐QoL‐14
3.4.1. Floor and ceiling effects
In the everyday life subscale, 22 (7.3%) patients achieved the lowest score, indicating a small floor effect, but not in the other (sub)scales (n = 3, 1.0% to n = 13, 4.3%). Considerable ceiling effects were detectable for the psyche (n = 39, 12.9%) and everyday life subscales (n = 27, 8.9%), but not for the body subscale (n = 11, 3.6%) or the global scale (n = 4, 1.3%).
3.4.2. Internal consistency
Internal consistency (Table 6) was good for all scales (global: Cronbach's α = 0.925, n = 276; everyday life: 0.918, n = 294; psyche: 0.881, n = 294; body: 0.779, n = 289).
3.4.3. Item selectivity
Item selectivity (Appendix S1) of the global score ranged from r = 0.548 to r = 0.808 with highest correlations in items on everyday activities (r = 0.808), being unhappy (r = 0.793) and recreational activities (r = 0.782). Lowest correlations were seen in items on disturbing discharge from the wound (r = 0.548) and wound smell (r = 0.562). Subscale item selectivity ranged from r = 0.672 to r = 0.828 for body subscale, from r = 0.842 to r = 0.888 for the psyche subscale and from r = 0.817 to r = 0.902 for the everyday life subscale.
3.4.4. Convergent validity
Convergent validity (Table 7) with other PROMs was high, showing largest effect sizes for the global rating scale (r = 0.751, p < 0.001, n = 289) and the DLQI total score (r = 0.681, p < 0.001, n = 294). Correlation with EQ VAS revealed moderate effect size (r = −0.473, p < 0.001, n = 296).
Correlations between the body subscale and the DLQI symptoms and feelings subscale (r = 0.594, p < 0.001, n = 297) and the DLQI treatment subscale (r = 0.426, p < 0.001, n = 300) showed large to medium effect sizes; correlation between the psyche subscale and the DLQI relationships subscale (r = 0.375, p < 0.001, n = 295) showed medium effect size; and correlations between everyday life subscale and the DLQI leisure subscale (r = 0.501, p < 0.001, n = 288) and the DLQI work and school subscale (r = 0.208, p < 0.001, n = 292) showed medium to low effect sizes.
Convergent validity analyses regarding clinical data showed medium effects regarding odour (r = −0.388, p < 0.001, n = 296), wound size (r = 0.383, p < 0.001, n = 283) and amount of exudate (r = 0.318, p < 0.001, n = 292). Other clinician‐reported outcomes showed only small, but statistically significant effects.
3.4.5. Test–retest reliability
Test–retest reliability (Table 8) was good for the global scale (ICC = 0.751, 95% CI = 0.636, 0.828) and the everyday life subscale (ICC = 0.797, 95% CI = 0.723, 0.853), and moderate for the psyche subscale (ICC = 0.696, 95% CI = 0.581, 0.781) and the body subscale (ICC = 0.618, 95% CI = 0.460, 0.731) of the Wound‐QoL‐14.
TABLE 8.
Test–retest reliability of the Wound‐QoL‐17 and Wound‐QoL‐14 in patients with retest completion within 5–9 days after baseline.
| Wound‐QoL‐17 | Wound‐QoL‐14 | |||||
|---|---|---|---|---|---|---|
| ICC | 95% CI | n | ICC | 95% CI | n | |
| Global scale | 0.771 | 0.665, 0.842 | 129 | 0.751 | 0.635, 0.828 | 129 |
| Body subscale | 0.622 | 0.465, 0.734 | 128 | 0.618 | 0.460, 0.731 | 129 |
| Psyche subscale | 0.703 | 0.584, 0.789 | 129 | 0.696 | 0.581, 0.781 | 129 |
| Everyday life subscale | 0.808 | 0.736, 0.861 | 128 | 0.797 | 0.723, 0.853 | 128 |
Abbreviations: 95% CI, 95% confidence interval; ICC, intraclass correlation coefficient; n, number of participants.
3.5. Country‐specific results
Country‐specific validation (Appendix S1) could be performed for Austria (n = 51), Lithuania (n = 50), Poland (n = 50), Ukraine (n = 42), Slovakia (n = 41) and the Netherlands (n = 37), but not for Switzerland (n = 13) and Spain (n = 12). There were no relevant differences in psychometric properties data across countries.
4. DISCUSSION
The aim of the study was to analyse psychometric properties of the Wound‐QoL‐17 and the Wound‐QoL‐14 in a European sample. Results of psychometric analyses confirm that both Wound‐QoL versions are valid instruments for the use in clinical practice and international studies. The validation data in this international cohort are satisfying and show no relevant differences between the 17‐ and the 14‐item version.
None of the items had a remarkably high number of missing values, while previous studies in Dutch and German samples 14 , 30 found many missing values for the item on climbing stairs (which might be influenced by the physical and the structural conditions of the patients (mobility, functioning) and their residences (e.g. no upper floors, lifts)). In both versions, ceiling effects were seen for psyche and everyday life subscales, highlighting the impact the condition can have on non‐physical areas of life, but also indicating that the scales may not be able to completely distinguish between very high and extremely high impairment in these areas.
As in previous studies, internal consistency was lowest for the body subscale, 13 , 14 , 17 , 18 but still internal consistency was good for all scales.
In consistency with previous studies, 14 items on every day and recreational activities showed highest values in item selectivity regarding the Wound‐QoL‐17 global scale indicating the importance of exerting these activities have on patients' HRQoL. Likewise, the everyday life subscale correlated highest with the Wound‐QoL‐17 global scale. Wound‐QoL‐14 showed similar results.
Results on convergent validity for both versions largely confirmed the pre‐defined hypotheses with largest effect sizes regarding DLQI, global HRQoL rating and EQ‐5D‐5L. With regard to pain measures, convergent validity showed large effect sizes; in previous studies, effect size of correlations with pain varied from small to large. 14 , 16 , 22 As expected, effect sizes were larger for pain at rest than for pain during dressing change. Odour showed the largest and second largest effect size among the clinical variables; in a previous study, 14 odour was hypothesised to have a high impact on HRQoL but could not be analysed as it had not been assessed. Patient‐reported smell (item of the Wound‐QoL) correlated higher with the Wound‐QoL total score compared with clinician‐reported odour but had one of the lowest correlations compared with other Wound‐QoL items in item selectivity analysis. This highlights the importance of psychosocial components of HRQoL as compared to the physical and clinical aspects.
Retest results were moderate for body and psyche subscales and good for global scale and everyday life subscale. A previous study revealed higher retest reliability. 20 This difference might be explained by the different settings. While the previous study assessed retest reliability in patients treated by a mobile nursing service throughout routine care, the patients in this study visited ambulatory clinics where they received treatment at the date of baseline assessment. Accordingly, actual change might have occurred during the recall period, which is supported by the decrease in mean scores (results not displayed; with highest decline (−0.33) in body subscale).
The major strength of this study was its international approach, allowing for both a combined analysis of the whole sample of more than 300 patients and a comparison of country‐specific results. This validation supports the use of both Wound‐QoL versions in European samples. It confirms previous single‐country studies confirming validity of the Wound‐QoL‐17, and it is the first study analysing psychometric properties of the Wound‐QoL‐14 beyond internal consistency.
Limitations of this study were that only eight instead of 10 countries participated in the study and that not all participating countries reached the targeted sample size, resulting in a sample size of 305 patients with an unequal distribution across countries. While some recruiting centres stated that recruitment of patients posed no problem and they recruited subsequent patients, other stated that the ability to read and answer questionnaires lead to exclusion of potential participants according to the study inclusion criteria. Lower ability of patients to read and answer questionnaires has also brought about physicians or nurses to read out the questionnaire to some patients. As self‐completion and answering to read‐out version of the Wound‐QoL might result in different response behaviour, 14 documenting the completion mode might be useful to assess how comparable results of different time points are or whether the information might be influenced by a helping person.
The Wound‐QoL is a frequently used instrument in clinical practice and research. On item level, patients' answers can be used for treatment planning and enhancing compliance; on scale level, scores can be used to evaluate treatment. Profound results about psychometric properties are necessary to confirm the reliability and validity of patient‐reported data. This manuscript adds comprehensive validation data for the Wound‐QoL‐17 to the existing body of literature; it is the first study analysing these properties on a European level and including data on Central/Eastern European countries. For the Wound‐QoL‐14, it is the first study analysing psychometric properties such as convergent validity and test–retest reliability. As this short version has only been established after the start of the present study, the data here present a ‘virtual validation’ (i.e. patients completed the longer version and responses on the items included in the shorter version were analysed 11 ). In a future study, the Wound‐QoL‐14 should be completed in its original length to confirm its good psychometric properties found in this study, as it cannot be ruled out that the overall item set resulted in slightly different response behaviour.
In clinical practice where time is rare, the Wound‐QoL‐14 might be preferable considering its good psychometric properties and brevity. The availability of various language version allows the use of this questionnaire not only in international studies but also in clinical practice when foreign language patients are being treated.
FUNDING INFORMATION
This study was partially funded by the European Academy for Dermatology and Venereology (EADV).
CONFLICT OF INTEREST STATEMENT
TMJ, VK, SV, LR, PC, MJ, CVM, SA, MB and ECM report to have no conflicts of interest. AR has been a consultant or speaker for AbbVie, Bioderma, Boehringer Ingelheim, Celgene, Chema Elektromet, Eli Lilly, Galderma, Janssen, Leo Pharma, Medac, Menlo Therapeutics, Novartis, Pierre‐Fabre, Sandoz and Trevi Therapeutics; and principal investigator or subinvestigator in clinical trials sponsored by Abbvie, Alvotech, Amgen, AnaptysBio, Argenx, Biothera, BMS, Celgene, Celltrion, Dermira, Galderma, Inflarx, Janssen, Kiniksa, Kymab, Leo Pharma, Novartis, Pfizer, Trevi Therapeutics, UCB. KS participated in clinical trials as subinvestigator sponsored by Amgen, Anaptys, Almirall, Celltrion, Galderma, Kiniksa, Novartis, Trevi Therapeutics and was an invited speaker by Medac and Novartis. MA has received fees for consulting and/or lectures and/or studies from the following companies: 3 M Medica, AOK Bundesverband, Bayer Healthcare, Beiersdorf, Birken, Bode, B. Braun, BSNmedical/Essity, BVmed, Coloplast, DAK, Diabet concept, Gerromed, GlaxoSmithKline, Johnson & Johnson, Lohmann & Rauscher, medi, Medovent, Mölnlycke, Smith & Nephew, Schülke & Mayr, Söring, Sorbion, Systagenix, Uluru, Urgo. Project proposal has been submitted by MA. CB is project lead of the HAQOL study, which has been partly funded by the EADV.
Supporting information
Appendix S1. Supporting Information.
ACKNOWLEDGEMENTS
The authors thank the Scientific Communication Team of the IVDP, in particular Sara Tiedemann and Mario Gehoff, for copy editing. Open Access funding enabled and organized by Projekt DEAL.
Janke TM, Kozon V, Valiukeviciene S, et al. Validation of the Wound‐QoL‐17 and the Wound‐QoL‐14 in a European sample of 305 patients with chronic wounds. Int Wound J. 2024;21(3):e14505. doi: 10.1111/iwj.14505
DATA AVAILABILITY STATEMENT
Data are available on reasonable request from the corresponding author.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Appendix S1. Supporting Information.
Data Availability Statement
Data are available on reasonable request from the corresponding author.