Abstract
Many patients with chronic wounds suffer not only directly from their wounds but also from high financial, social and psychological impairments, significantly reducing their quality of life. In order to provide an instrument both applicable to different patient populations and sensitive to areas of impact specific to certain skin diseases, the modular instrument ‘Freiburg Life Quality Assessment' has been developed. Each disease‐specific version of the instrument consists of a core module of generic items and items specific for a distinct skin disease.
Objective of the study was to assess reliability, sensitivity to change, and validity of the module for chronic ulcers.
The instrument was implemented in a longitudinal observational study on vacuum‐seal therapy (n = 175), in a cross‐sectional observational study involving patients with chronic leg ulcers (n = 384) and in a randomised clinical trial on keratinocyte transplantation (n = 198).
The instrument showed good internal consistency (Cronbach's alpha ≥0·85). There were minor floor effects ≤4·3%, but no ceiling effects. Retest‐reliability and convergent validity with the EuroQol quality of life questionnaire (EQ‐5D) (visual analogue scale) were satisfactory. Change scores correlated with change in other quality‐of‐life instruments (r = 0·59–0·61), but not with change in wound status.
Keywords: Chronic wounds, Health‐related quality of life, Questionnaire, Skin diseases, Validation
INTRODUCTION
Chronic wounds are burdensome and economically relevant diseases. However, prevalence rates are conflicting. For example in a population‐based German study, leg ulcers were found with a 4‐week prevalence of about 0·3% (1), whereas other estimations indicated a prevalence of more than 1% (2).
Annual costs amount to billions of Euros. Beside the direct burden of chronic wounds, leg ulcers, including venous ulcers, often cause the patients high financial, social and psychological impairment (3). Many patients with ulcers have a significantly reduced health‐related quality of life (HRQoL) (4).
HRQoL refers to the quality of the life of an individual regarding physical, psychological, social and functional aspects (5). HRQoL is further divided into generic quality of life and disease‐specific quality of life, the latter focussing on specific characteristics of certain diseases.
The link between HRQoL and ulcers is two‐way: while healing of leg ulcers is related to improvements in quality of life 6, 7, 8, psychosocial factors of HRQoL can impact on wound healing, too (9).
HRQoL has gained substantial interest in almost all fields of clinical medicine, including a variety of dermatological diseases (10). Guidelines for the evaluation of HRQoL in dermatology have been published for Germany (11).
Although HRQoL cannot be measured directly, many methodological studies have confirmed that it can be fairly assessed by questionnaires focussing on distinct areas contributing to HRQoL 12, 13, 14.
The most common instruments for the assessment of HRQoL in dermatology are the Dermatological Life Quality Index (DLQI) (15) and the Skindex (16), both well‐validated and feasible disease‐specific HRQoL instruments for use in skin diseases. While these questionnaires are very useful in evaluating dermatology‐specific HRQoL, comparisons between different skin diseases are limited. In order to provide an instrument that allows for comparisons between different patient populations but that is also specific and thus sensitive to certain skin diseases, we developed a modular HRQoL instrument: the Freiburg Life Quality Assessment (FLQA). Each specific FLQA version consists of a core module of generic items and a number of specific items for a distinct skin disease. This article presents the development and validation of the FLQA wound module (FLQA‐w) for the assessment of HRQoL in chronic wounds.
METHODS
Development of the FLQA‐w module
The FLQA‐w was developed on the basis of the ‘Freiburg questionnaire of quality of life in venous diseases', which has been validated in n = 246patients with chronic venous insufficiency (17). Of the original 81 items, 10 were maintained without changes, 10 items were modified and 61 items were omitted. 3 new items covering wound‐specific impairments relating to pain and itching at the ulcer and to ulcer efflux were added. The resulting 24 items are divided into a dermatology generic FLQA core version (FLQA‐c) including 17 items and a disease‐specific module of 6 items related specifically to ulcers. The item scaling is 1 = never/not at all to 5 = always/very much. The item assessing the time needed for daily wound treatment is scaled from 1 = ‘no time′ to 5 = ‘more than 60 minutes′.
The FLQA scales may be compared to three additional visual analogue scales (VAS, 10 cm) which indicate general health, quality of life in general and quality of life with respect to the wound.
Computing FLQA‐w scores
The FLQA‐w consists of the following six scales: physical ailments, everyday life, social life, psychological well‐being, satisfaction in different areas of life, and therapy. After recoding the three items of the FLQA‐w subscale ‘satisfaction’, higher values represent higher impairment of HRQoL in all items. Subscales are computed by averaging the respective items on each dimension, and a total score is computed by averaging all items. Accordingly, the total score and the subscales range from 1 to 5. To compute a subscale score, responses to a minimum of 75% of the respective items of a scale have to be valid. A global score is computed by averaging the six scale scores unless there is more than one invalid scale.
Validation studies
The FLQA‐w was validated in three different studies involving patients with acute and chronic wounds. Clinical results of these studies are published elsewhere 18, 19. Table 1 shows an overview of validation procedures in the three studies.
Table 1.
Analyses performed for validation of the Freiburg Life Quality Assessment, wound module (FLQA‐w) in each study
| Study 1: Vacuum‐seal therapy | Study 2: Leg ulcers | Study 3: Keratinocyte transplantation | |
|---|---|---|---|
| General characteristics: | |||
| Corrected item‐total correlations | × | × | × |
| Floor/ceiling effects | × | × | × |
| Missing values | × | × | × |
| Reliability: | |||
| Internal consistency | × | × | × |
| Retest‐reliability | × | ||
| Convergent validity: | |||
| EQ‐5D (quality of life) | × | ||
| Global assessment of quality of life | × | × | |
| Intensity of pain | × | ||
| Sensitivity to change: | |||
| Wound area | × | ||
| Wound status | × | ||
| EQ‐5D | × | ||
| Global assessment of quality of life | × | ||
| Treatment success | × | ||
| Pre–post‐comparison | × | ||
EQ‐5D, EuroQol quality of life questionnaire. See text for further explanation.
Study 1: VVS therapy
Study design and patients
The FLQA‐w was given to n = 210patients with acute and chronic wounds in a multicentre, non‐controlled, open observational questionnaire study of treatment with vacuum‐seal therapy (VVS therapy, KCI International, Wiesbaden, Germany). Standardised questionnaires were filled in by both physicians and patients prior to VVS therapy (t1) and at the end of VVS therapy after 2–4 weeks (t2). Data of the FLQA‐w at both measurement times were available for n = 175patients.
Analysis
The following validation analyses were performed using data from study 1:
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•
distributional characteristics of the FLQA‐w (t1):
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corrected item‐total correlation
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floor and ceiling effects of total score
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percentage of missing values
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•
reliability: internal consistency of the FLQA‐w (t1)
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•
convergent validity: correlation of the FLQA‐w at t1 with:
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generic HRQoL as measured with the EuroQol quality of life questionnaire (EQ‐5D)(20)
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patient's global assessment of general quality of life in the preceding week, measured with a VAS ranging from 0 = very poor to 10 = very good
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•
sensitivity to change: correlation of the FLQA‐w at t2 (while statistically controlling for FLQA‐w at t1) with the following variables (each statistically controlled for the respective values at t1):
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wound area (length by width)
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wound status: sum of physician's judgements on percentage of wound area covered with a) necrosis, b) fibrin, c) granulation and d) epithelisation, respectively, using a 5‐point scale (1 = 0%, 2 = up to 25%, 3 = up to 50%, 4 = up to 75%, 5 = up to 100%)
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generic HRQoL, measured by the EQ‐5D
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patient's global assessment of quality of life in the preceding week
In the literature, there are conflicting definitions of ‘sensitivity to change’ and ‘responsiveness’21, 22. In this study, both terms are considered equivalent.
Study 2: Leg ulcers
Study design and patients
This cross‐sectional observational study evaluated health services in Germany, enrolling n = 502patients with chronic leg ulcers treated with various therapies. Both physician and patient filled in a questionnaire. Data were collected at one point in time only. N = 384patients filled in the FLQA‐w.
Analysis
The FLQA‐w data were analysed regarding:
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•
distributional characteristics: as in study 1 (see above)
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•
reliability: internal consistency of the FLQA‐w
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•
convergent validity: correlation of FLQA‐w with:
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current intensity of pain, scale ranging from 0 (no pain) to 10
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patient's global assessment of general quality of life in the preceding week, as in study 1 (see above)
Study 3: Keratinocytes
Study design and patients
Lastly, the FLQA‐w was implemented in an open label randomised multicentre study comparing efficacy and safety of keratinocyte transplantation plus compression therapy (BioTissue Technologies, Freiburg, Germany) to standard therapy in the outpatient treatment of chronic leg ulcers of venous insufficiency origin. N = 198 of the 240 patients enclosed filled in the FLQA‐w at t1 (day 0), t2 (day 28) and t3 (day 56). From t1 to t2, all patients received standard therapy. At t2, half of the patients were randomised to keratinocyte transplantation until t3, whereas the other half received conservative standard therapy in this period.
Analysis
The FLQA‐w was analysed regarding:
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•
distributional characteristics, as in study 1 (see above)
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•
retest‐reliability: internal consistency of the FLQA‐w (t1); correlation of FLQA‐w scores at t1 and t2. As patients had already been treated before study onset, it was assumed that standard therapy which patients received between t1 and t2 did not systematically change HRQoL.
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•
sensitivity to change:
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correlation of the FLQA‐w at t3 (statistically controlling for FLQA‐w at t2) with patient's rating of treatment success at t3, assessed on a 5‐point scale (1 = very successful to 5 = not successful at all)
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Comparison of FLQA‐w scores before (t2) and after transplantation (t3)
Statistics
t‐Tests for paired samples were computed for pre–post‐treatment comparisons. Correlations were computed by Pearson's correlation coefficients. Statistical control for t2 values was achieved by performing a linear regression analysis of the t2 values on the criterion values; the resulting residuals were saved and used for correlation. Cronbach's alpha was chosen as a measure of reliability in terms of internal consistency. Corrected item‐total correlations were computed by Pearson's correlations. Floor and ceiling effects of FLQA‐w scores were defined as values in the first and tenth percentile of the score range, that is <1·5 or >4·5. The level of significance was set at P = 0·05 (two‐sided). All statistical analyses were performed using SPSS 15·0 for Windows.
Ethics
For the validation study reported in this article, only pre‐existing anonymised data from three studies were used. Thus, no ethics approval was necessary. Approval from the local ethics committee had been obtained for the three studies, and all patients had given informed consent.
RESULTS
Patients
Mean age of the patients ranged from 59·4 (study 1) to 70·5 years (study 2, Table 2). The percentage of female patients ranged from 48·1% (study 1) to 63·1% (study 3). In study 3, mean ulcer size (13·3 cm2) was lower than in study 1 (78·8 cm2) and 2 (33·3 cm2). Patients in study 1 had higher average FLQA‐w values in all subscales, except for the physical subscale and the global score compared with patients in study 2 and 3, indicating lower HRQoL (Figure 1, Table 3). They also stated markedly less satisfaction with treatment, whereas their satisfaction with health and the state of their wounds was higher than in the other patients (Table 3).
Table 2.
Sociodemographic and clinical characteristics at baseline of each study
| Study 1: Vacuum‐seal therapy | Study 2: Leg ulcers | Study 3: Keratinocyte transplantation | |
|---|---|---|---|
| N | 175 | 384 | 198 |
| Sex: % female | 48·1 | 55·7 | 63·1 |
| Age: mean ± SD | 59·4 ± 16·2 | 70·5 ± 14·1 | 67·1 ± 12·3 |
| Age: range | 18–91 | 22–95 | 29–89 |
| Ulcer size (length × width in cm2) mean ± SD | 78·8 ± 137·2 | 33·3 ± 55·9 | 13·3 ± 17·1 |
| Ulcer size: median | 35·0 | 6·8 | n.a. |
| Ulcer size: range | 0·3–900·0 | 0·16–255·0 | n.a. |
Figure 1.
Mean Freiburg Life Quality Assessment, wound module (FLQA‐w) values and standard deviations in the three studies: subscales and global score. Higher values indicate lower health‐related quality of life.
Table 3.
Distributional characteristics of Freiburg Life Quality Assessment, wound module (FLQA‐w) items at baseline of each study
| FLQA‐w item | Study 1: Vacuum‐seal therapy | Study 2: Leg ulcers | Study 3: Keratinocyte transplantation | |||
|---|---|---|---|---|---|---|
| Mean * | SD | Mean * | SD | Mean * | SD | |
| Physical ailments: | ||||||
| Pain from the wound | 3·3 | 1·4 | 3·3 | 1·2 | 3·6 | 1·2 |
| Sleeping problems | 2·8 | 1·3 | 2·7 | 1·3 | 2·8 | 1·2 |
| Itching from the wound | 2·2 | 1·2 | 2·3 | 1·2 | 2·5 | 1·3 |
| Wound discharge | 3·8 | 1·3 | 3·2 | 1·5 | 3·7 | 1·3 |
| Everyday life: | ||||||
| Inability to sufficiently perform tasks in household/job | 3·1 | 1·6 | 2·7 | 1·3 | 2·8 | 1·1 |
| Difficulties with physical exertion | 3·9 | 1·1 | 3·3 | 1·4 | 3·2 | 1·2 |
| Restrictions of leisure activities | 4·4 | 1·0 | 3·6 | 1·4 | 3·4 | 1·4 |
| Stair climbing is difficult | 3·9 | 1·4 | 3·3 | 1·5 | 3·4 | 1·4 |
| Financial burden | 2·6 | 1·6 | 2·9 | 1·5 | 2·8 | 1·3 |
| Social life: | ||||||
| Limited social activities | 4·0 | 1·4 | 3·1 | 1·6 | 2·7 | 1·5 |
| Dependence on help by others | 3·8 | 1·4 | 2·9 | 1·6 | 2·5 | 1·4 |
| Withdrawing from others | 2·8 | 1·5 | 2·2 | 1·4 | 2·0 | 1·2 |
| Psychological well‐being: | ||||||
| Anger and rage | 2·7 | 1·3 | 2·3 | 1·2 | 2·3 | 1·1 |
| Dejection | 2·9 | 1·2 | 2·7 | 1·3 | 2·6 | 1·1 |
| Exhaustion and tiredness | 3·1 | 1·2 | 2·9 | 1·2 | 2·9 | 1·1 |
| Helplessness | 3·1 | 1·4 | 2·5 | 1·4 | 2·1 | 1·2 |
| Therapy: | ||||||
| Treatment is a strain | 3·4 | 1·4 | 2·8 | 1·3 | 2·7 | 1·3 |
| Treatment is time consuming | 3·3 | 1·3 | 2·8 | 1·3 | 3·0 | 1·4 |
| Dependency on assistance from others | 4·2 | 1·2 | 3·3 | 1·7 | 2·4 | 1·6 |
| Time needed for daily treatment | 3·2 | 1·1 | 2·9 | 0·9 | 3·3 | 1·0 |
| Satisfaction: | ||||||
| Satisfaction with health † | 1·6 | 1·3 | 2·0 | 1·3 | 1·9 | 1·1 |
| Satisfaction with treatment † | 3·8 | 1·2 | 0·9 | 1·0 | 1·2 | 1·1 |
| Satisfaction with state of wound † | 1·5 | 1·4 | 2·2 | 1·4 | 2·4 | 1·2 |
*Item scaling: 1–5 with higher scores indicating higher impairment and thus lower health‐related quality of life.
†Values have been recoded to 1–5 with higher scores indicating higher impairment and thus lower health‐related quality of life.
General parameters
Corrected item‐total correlations of the FLQA‐w items were widespread with values ranging from 0·13 to 0·73 (Table 4). The items with lowest and highest correlation were: itching from the wound (lowest) and pain from the wound (highest) in study 1; satisfaction with treatment (lowest) and difficulties with physical exertion (highest) in study 2; satisfaction with treatment (lowest) and restrictions of social activities (highest) in study 3.
Table 4.
Distributional characteristics, reliability, validity, and sensitivity to change of the Freiburg Life Quality Assessment, wound module (FLQA‐w) in each study
| Study 1: Vacuum‐seal therapy * | Study 2: Leg ulcers | Study 3: Keratinocyte transplantation * | |
|---|---|---|---|
| General parameters: | |||
| Missing values: percentage of missing items per patient, mean (SD) | 1·9 (5·5) | 1·9 (7·3) | 1·4 (4·8) |
| Corrected item‐total correlations (range) | 0·13–0·61 | 0·13–0·73 | 0·13–0·69 |
| Floor and ceiling effects (percentage of patients with global score <1·5/>4·5) | 0·0/0·0 | 4·3/0·3 | 3·1/1·0 |
| Reliability: | |||
| Internal consistency (Cronbach's alpha) | 0·86 | 0·86 | 0·87 |
| Retest‐reliability (r, P) | n.a. | n.a. | 0·69 (0·001) |
| Convergent validity (r, P): | |||
| EQ‐5D (quality of life) | 0·59 (0·001) | n.a. | n.a. |
| General quality of life | −0·38 (0·001) | −0·67 (0·001) | −0·67 (0·001) |
| Pain | n.a. | 0·41 (0·001) | n.a. |
| Sensitivity to change (r, P) † : | |||
| Wound area | −0·04 (0·68) | n.a. | n.a. |
| Wound status | −0·14 (0·10) | n.a. | n.a. |
| EQ‐5D (quality of life) | 0·61 (0·001) | n.a. | n.a. |
| General quality of life | −0·58 (0·001) | n.a. | n.a. |
| Treatment success | n.a. | n.a. | −0·47 (0·001) |
| N | 175 | 384 | 198 |
EQ‐5D, EuroQol quality of life questionnaire.
*In study 1 and 3, general parameters, Cronbach's alpha and convergent validity refer to baseline.
†Correlations of FLQA‐w with criteria variables are statistically controlled for baseline differences.
Ceiling effects were small with less than 1% of the patients scoring above a global score of 4·5 (Table 4). Floor effects could be found in study 2 and 3, with up to 4·3% of the patients scoring lower than 1·5. However, no patient had the lowest or highest possible value of 1 or 5.
The percentage of items not answered by the patients (missing values, Table 4) was lower than 2% in all studies. The global score could thus be calculated in 97·1% (study 1: n = 170; study 2: n = 373) or 98·5% (study 3: n = 195) of the participants.
Reliability
Cronbach's alpha coefficients were satisfactory in all three studies with values of 0·86 and 0·87. Four‐week retest‐reliability (correlation of FLQA‐w at study onset with FLQA‐w before transplantation) was significant, but only moderate (r = 0·69, Table 4). In fact, it was lower than the correlation of FLQA before (T2) and after transplantation (T3, r = 0·78, P < 0·001).
Convergent validity and sensitivity to change
Convergent validity was highly significant and of moderate level at least. Regarding patient's global assessment of quality of life, the correlation coefficients ranged from r = 0·38 in the VVS therapy study to r = 0·67 in the other two studies.
Sensitivity to change in clinical status (wound area and wound status) was low and not significant.
There was a marked and highly significant correlation between FLQA global score and a) EQ‐5D, b) ‘general quality of life’ VAS and c) treatment success (r = 0·61, −0·58 and −0·47).
Regarding keratinocyte transplantation, satisfactory sensitivity to change was found for all scales of the FLQA‐w: 28 days after transplantation, patients had lower values in all domains, indicating increased HRQoL (Table 5).
Table 5.
Sensitivity to change of Freiburg Life Quality Assessment, wound module (FLQA‐w) subscales in study 3: means and standard deviations before and 28 days after keratinocyte transplantation
| FLQA‐w scales * | T2: Before transplantation: mean (SD) | T3: After transplantation: mean (SD) | P † | n |
|---|---|---|---|---|
| Physical ailments | 2·9 (0·9) | 2·6 (0·9) | <0·001 | 195 |
| Everyday life | 3·0 (0·9) | 2·8 (1·0) | <0·001 | 192 |
| Social life | 2·3 (1·2) | 2·2 (1·1) | 0·007 | 194 |
| Psychological well‐being | 2·4 (0·9) | 2·3 (0·9) | 0·001 | 196 |
| Therapy | 2·8 (1·0) | 2·7 (1·0) | 0·009 | 195 |
| Satisfaction | 2·5 (0·8) | 2·3 (0·8) | <0·001 | 190 |
| Total score | 2·7 (0·8) | 2·5 (0·8) | <0·001 | 194 |
EQ‐5D, EuroQol quality of life questionnaire.
*Higher scores indicate higher impairment of health‐related quality of life.
† t‐Test for paired samples. When applying a Bonferroni correction to the multiple testing of six subscales, all tests remain significant at the joint P = 0·05.
DISCUSSION
The aim of this study was to assess the validity of the FLQA‐w questionnaire, a disease‐specific HRQoL instrument for patients with chronic wounds. The results support the conclusion that the FLQA‐w is a feasible, internally consistent and valid instrument for the assessment of HRQoL in chronic wounds which is sensitive to changes in HRQoL, albeit not in wound status.
However, retest‐reliability was only moderate. Reason for this might be that the underlying assumption of constant HRQoL from study onset to keratinocyte transplantation was wrong. Some of the patients may have experienced an improvement of HRQoL because of intensive wound bed preparation, placebo effects resulting from participation in a clinical study, or the patients' expectance of clinical improvements by therapy. This is supported by the finding that the mean FLQA‐w increased highly significantly from t1 to t2 which cannot be attributed to unreliability of the instrument (T1: 2·81 ± 0·71; T2: 2·66 ± 0·75; P < 0·001). Therefore, retest‐reliability should be further assessed in observational studies administering no intervention between two completions of the FLQA‐w.
Low sensitivity to change in wound area found in study 1 might be attributed to the fact that wound size and quality of life do not correspond well, because in some body areas, a small decrease in size can cause great increases in quality of life, and vice versa. Sensitivity to change to other quality‐of‐life measures and the patients' assessment of treatment success, however, indicates good ability of the FLQA‐w to detect changes.
For use in international studies, the FLQA‐w has been translated into English according to the principles of good practice for translating patient‐reported outcome measures (23).
In conclusion, the FLQA‐w is a reliable, sensitive and valid measure of HRQoL in chronic ulcers.
ACKNOWLEDGEMENTS
The studies on VVS therapy and keratinocytes have been supported by research grants from KCI International, Wiesbaden/Germany, and BioTissue Technologies, Freiburg/Germany, respectively. M.A. was invited speaker for both companies. M.A. is licence holder of the FLQA‐w.
The work should be attributed to: CVderm, German Center for Health Services Research in Dermatology, Institute for Health Services Research in Dermatology and Nursing, University Clinics of Hamburg, Germany.
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