Translation and Validation of a Wound-specific, Quality-of-life Instrument (The Wound-QoL) in a Swedish Population
Hard-to-heal wounds can compromise patient quality of life (QoL); thus, assessing QoL is an important aspect of wound management. The aim of this study, conducted from August 2015 to July 2016, was to translate a wound-specific instrument, the Wound-QoL, into the Swedish language and context and validate its ability to assess QoL in a population of patients with wounds of various etiologies.
The Wound-QoL, derived from 3 existing wound care QoL instruments, is a paper-and-pencil tool comprised of 17 Likert-style questions addressing 3 categories (Body, Psyche, and Everyday Life) to provide a global score. The instrument was translated into Swedish and its psychometric properties (reliability, validity, responsiveness, and ceiling and floor effect) were tested in a convenience sample of 88 Swedish outpatients (64 men [73%], mean age 67 [range 27–96] years) with hard-to-heal wounds (mean duration 10 months) of varying etiologies. Participants completed the questionnaires at baseline in the beginning of the study and at 6 weeks; they also had the opportunity to comment on the questionnaire. Reliability was analyzed using Cronbach’s alpha coefficient (0.70 or higher was considered acceptable). Criterion validity was examined using a generic European QoL instrument, considered the gold standard, as the comparator. Descriptive statistical analysis was performed for presentation of the demographic and wound variables. Standardized response mean was used to assess internal responsiveness. All tests were 2-sided with 95% confidence interval; the results were considered significant at P <.05. QoL scores of the study population in the different domains measured with the Wound-QoL instrument varied from 1.11 to 1.72. Reliability was excellent, with internal consistency of 0.78-0.92 and test-retest stability of 0.80-0.88; standardized response mean showed small to moderate sensitivity; and validity was found to be slightly moderate to moderate. No signs of ceiling or floor effect could be detected. The Swedish version of the Wound-QoL instrument was found to be a reliable and valid tool for measuring health-related QoL in patients with hard-to-heal wounds in Sweden and demonstrated the potential to be used in a clinical setting to detect QoL issues during wound treatment. Further psychometric studies need to be performed to validate the instrument in patient groups with acute wounds, with different wound treatments, and for patients treated in nonspecialized wound care settings such as home care.
Hard-to-heal (ie, wounds that fail to heal within an expected time frame and order1) can compromise patient quality of life (QoL), as shown in both qualitative and quantitative research.2,3 A review4 of randomized controlled trials and comparative studies of nonhealing wounds published between 2003 and 2009 shows >300 different endpoints are used to evaluate wound management; the majority of the endpoints are directly related to complete wound healing (perceived as the most meaningful endpoint) with healing rates and time for complete healing as primary outcomes.5 However, experts tend to focus on patient-related outcomes such as QoL in research of nonhealing wounds.6
Health-related quality of life (HRQOL) is a multidimensional concept and can be defined as a person’s subjective perception of his/her overall physical and mental health.7 HRQOL in patients with venous leg ulcers has been addressed in systematic reviews3,8,9 that demonstrate the negative impact of these wounds on patient well-being. Similar results have been found in several reviews of both quantitative and qualitative studies among patients with diabetic foot ulcers7 and pressure ulcers.10,11
HRQOL can be measured with generic instruments that lend a broad perspective on health and target nonspecific patient groups. Commonly used generic instruments for assessing HRQOL in patients with wounds are the Short Form-36 (SF-36), a 36-item, patient-completed survey that consists of 8 scaled scores; and the EuroQol Five-dimensional Descriptive System (EQ-5D-3L).12 The EQ-5D-3L consists of 2 parts; the first covers 5 dimensions (mobility, self-care, ability to undertake usual activities, pain/discomfort, and anxiety/depression); the 3 answer options are no problems, some problems, and difficult problems, which generate an index to be used in analysis. The second part consists of a Visual Analog Scale (VAS) where the respondents rate their perception of their health by marking a line. The VAS scale ranges from 0 to 100, where 0 indicates the worst possible conditions and 100 indicates the best possible conditions.
Instruments also have been developed to target the experience of health-related life aspects specific to a disease or condition.13 When measuring HRQOL of patients, descriptive or comparative studies recommend use of a combination of a generic instrument and a condition-specific instrument.14 The Cardiff Wound Impact Schedule15 (CWIS) was developed to meet the need for a wound-specific HRQOL instrument. This 47-item tool was designed to measure general health, physical symptoms, daily life, social life, and overall QoL in patients with chronic wounds. The instrument has been translated and validated into several languages and contexts16-18 including Swedish.19 However, the CWIS instrument has drawbacks; patients have described the questionnaire as too extensive, and several validation studies19,20 of the instrument noted a relatively high dropout rate during psychometric testing. In view of these problems, a new wound-specific HRQOL instrument was created, the Wound-QoL. The aim of this study was to validate the translation of the Wound- QoL instrument into Swedish language and context.
Materials and Methods
The Wound-QoL instrument. The Wound-QoL instrument was developed by the Institute for Health Services Research in Dermatology and Nursing at University Medical Center, Hamburg, Germany, to fulfill a need for a short, easy-to-use, multidimensional questionnaire measuring HRQOL in patients with hard-to-heal wounds.20 The instrument is a combination of the English CWIS and 2 German wound specific instruments, The Freiburg Life Quality Assessment for Wounds and the Wurzburg Wound Score. Together, the 3 questionnaires comprised a total of 92, 5-point Likert-scaled items from which 17 items were extracted and prospectively analyzed in a virtual validation study. The items were assigned to 3 subscales according to the domains Body (items 1–5), Psyche (items 6–10), and Everyday living (items 11–16). The subscales were summed for an overall global score together with an additional question regarding financial impact. Each item is rated by the respondent on a 5-point Likert-scale where 0 = not at all and 4 = very much; 4 was the worse rated level of HRQOL (see Figure 1).
The psychometric properties (reliability, validity, responsiveness, ceiling and floor effect) then were tested in a validation study performed at 2 different German wound centers with a total sample size of 227 patients with hard-to-heal wounds of various etiologies, showing satisfactory psychometric properties according to internal consistency (Cronbach alpha >0.80), convergent validity (0.5-0.7), and responsiveness (P ≤.001).21 The instrument also was tested for test-retest reliability in a study of 100 patients with hard-to-heal wounds using intraclass correlation (ICC). The result showed excellent reliability (range 0.79-0.86) calculated from the questionnaires, with an interval of 3 to 7 days between first and second completion.22
The translation process. The English version of the Wound-QoL instrument was translated into Swedish according to instructions by the Standard Linguistic Validation Process created by MAPI Research Institute,23 a 7-step process that includes forward and backward translation and pilot testing. The translation process was a collaboration between independent translators and the research group. The re-translated version was sent to the creators of the original version of the instrument, the Institute for Health Services Research in Dermatology and Nursing at University Medical Center, Hamburg, Germany, who evaluated the translation, made adjustments, and gave their approval.
Materials and data collection. Using convenience sampling methods, patients >18 years old with hard-to-heal wounds treated at an outpatient wound clinic in a large city in Sweden were recruited while visiting the clinic for their scheduled wound treatment between August 2015 and July 2016. Patients with less than adequate cognition to complete the questionnaire and patients who had not mastered the Swedish language were excluded.
The patients were asked to complete the Swedish version of the Wound-QoL instrument as well as the generic HRQOL instrument EQ-5D-3L at baseline at study enrollment and after 6 weeks. For the 6-week follow-up, the questionnaires were either distributed at a planned revisit at the wound clinic or sent to the patients with a letter of instruction and a postage-prepaid envelope with instructions to return the forms within 1 week. The patients completed the questionnaires in paper-and-pencil format, then data were transferred into a computer file for analysis. Basic demographic information and wound data, including gender, age, and type and duration of the wound, were obtained from either the patient or his/her medical record in the wound clinic. Patients also were asked in an open-ended question to describe their general experience of completing the Wound-QoL questionnaire; the responses were registered as field notes by the researcher.
All patients gave their verbal informed consent to participate in the study. Patient confidentiality was ensured by coding the questionnaires and records; encoding was handled solely by the researcher in accordance with the Swedish Data Protection Act (SFS,1998:204). The study was performed according to the Helsinki Declaration, and study approval was obtained by the local Ethics Committee (2015/714-31).
Psychometric analysis and statistics. Data from all questionnaires were transferred into a computer program to assess reliability, validity, responsiveness, and ceiling and floor effects. SPSS version 23.0 (IBM, Armonk, NY) was used for all calculations, and all tests were 2-sided with a 95% confidence interval. The results were considered significant at P <.05. Descriptive statistical analysis was performed for presentation of the demographic and wound variables.
Reliability. Reliability was measured with internal consistency to estimate the correlation between the different items for each domain at baseline using Cronbach’s alpha coefficient; Cronbach’s alpha 0.70 or higher was considered acceptable.24 Stability (test-retest reliability) of the instrument over time was measured with an ICC of patients who rated their health as unchanged in the EQ-5D-3L at the 6-week follow-up. An acceptable level of ICC in this study was considered >0.70.25
Validity. Validity in this study was assessed by measuring criterion validity comparing the scores of the Wound-QOL to the gold-standard instrument (EQ-5D-3L), a process similar to that used by the developers of the Wound-QOL instrument.20 All 3 domains of the Wound-QoL instrument together with the global score were compared to the EQ-5D-3L time trade-off (TTO) index and to the EQ-5D-3L VAS (ie, the patient’s self-rated health). The correlations were calculated with Spearman’s rho due to data on an ordinal level and were expected to be negative and moderately strong based on the correlation from the development process.20 A moderately strong correlation was defined as 0.3 to 0.49 according to Cohen.26
Responsiveness. Standardized response mean (SRM) was used for assessing responsiveness, a measurement of the ability of the instrument to detect clinically important changes. The calculation was performed by dividing the difference between baseline and 6-week follow-up in the group assessing their health as improved at the 6-week follow up according to the EQ-5D-3L questionnaire. SRM <0.5 is considered as small ability to detect change, 0.5–0.8 is moderate, and >0.8 is large.27
Ceiling and floor effect. Ceiling and floor effects occur when the scores of an instrument reach the maximum or minimum possible score. If this is noted in 15% or more of the questionnaires, it is hard to detect improvement or decline in the rated health status.28
Of the 103 patients who agreed to participate in the study and completed the questionnaires at baseline, 92 (89%) completed the questionnaires at the 6-week follow-up. Of those, 4 patients were excluded; they were wheelchair users and not able to answer the EQ-5D-3L questions regarding mobility. Thus, 88 questionnaires (participants included 64 men [73%] and 24 women [27%], mean age 67 [range 27–96] years) were analyzed. All included patients had hard-to-heal wounds with a duration >6 weeks; the most common wound (36, 42%) was a diabetic foot ulcer. The mean QoL score at baseline measured with the Wound-QoL instrument for the different domains and global score ranged from 1.11 to 1.39; measured with the EQ-5D-3L, the index mean at baseline was 0.52 with a mean VAS score of 62 (see Table 1). All patients described the questionnaire as being easy to understand and not too extensive or time-consuming to complete.
Reliability. Cronbach’s alpha coefficient showed an excellent internal consistency for each of the 3 domains (Body [0.78], Psyche [0.89], and Everyday life [0.90]). Internal consistency for the overall global score of the Wound-QoL instrument had an alpha of 0.92.
Test-retest analysis was performed on questionnaires of the 29 patients who rated their perception of health at the 6-week follow-up as unchanged. All of the domains showed excellent stability with ICC >75 (Body [0.80], Psyche [0.84], and Everyday life [0.81]). The overall global score of the instrument also was excellent (ICC 0.88).
Validity. Criterion validity was calculated by correlating the overall global score and the different domains of the Wound-QoL instrument with the EQ-5D-3L index value (TTO) and the EQ-5D-3L VAS scale (see Table 2). The correlations were moderate for the category Everyday life (-0.44) and for the overall global score (-0.44). Criterion validity for the categories Body (-0.35) and Psyche (-0.32) was slightly less than moderate. All correlations were significant (P <.01).
Responsiveness. Internal responsiveness was assessed using SRM in the group that stated health was improved after 6 weeks per the EQ-5D-3L. The results presented in Table 3 show moderate SRM for the domains Body (0.60) and Psyche (0.51). The SRM was small for Global score (0.45) and for the domain Everyday life (0.30), which also was a nonsignificant value for the change from first assessment to 6 week follow-up.
Ceiling and floor effect. The Wound-QoL instrument showed no signs of unacceptable ceiling or floor effect. No participant received the lowest or the highest possible score in the overall global score (see Table 4).
The aim of this study was to translate the Wound-QoL, a wound-specific HRQOL instrument, into the Swedish language and context and validate the new version. The results of psychometric testing of the Swedish version showed acceptable reliability, validity, and responsiveness as well as no signs of ceiling and floor effect. These findings indicate the instrument could be used in a clinical setting to assess HRQOL in patients with hard-to-heal wounds in Sweden.
When assessing the external validity of the Swedish version of the Wound-QoL instrument, the only reference data available are from the creation of the original instrument; no other validation studies of the instrument have been published. The psychometric properties of the Swedish version proved to be similar to those of the original version of the Wound-QoL20-22 with regard to reliability, validity, responsiveness, and ceiling and floor effect. Also, the actual scores of perceived HRQOL measured with the Wound-QoL instrument were similar; the result with a range at baseline from 1.11 to 1.39 compared with the result of Sommer et al22 with scores ranging from 0.90 to 1.57. Both studies had the lowest scores in the Body domain. Together, this indicates acceptable external validity.
From their general comments, patients found the questionnaire was easy and not too extensive to complete, unlike the experiences related to the CWIS.19 A qualitative study29 using an open-ended question identified the key elements of using a HRQOL instrument successfully as a screening tool in the clinical setting determined it should not be time-consuming and not be perceived as a burden to the patient or staff. The results of the current study indicate the Wound-QoL instrument can be used as a clinical tool to detect HRQOL issues during wound treatment that need to be addressed; its use is not limited to research purposes.
During the 26th conference of the European Wound Management Association,30 some issues were noted regarding 1 item of the original Wound-QoL instrument, (item number 12, “…climbing stairs has been difficult because of the wound”). Some reports indicate patients viewed the question as offensive, especially if they had already provided a negative response to the previous question that states, “…I have had trouble moving about because of the wound.” The German creators of the original version of the instrument had made some calculation after removing item number 12 without affecting the psychometric scores in a negative way.30 In turn, the current researchers similarly removed the data in question without impacting the results of psychometric property item responses (data not shown). Thus, the instrument may be further shortened to 16 questions, but this new version of the instrument would need to undergo proper psychometric testing.
When designing this study, the EQ-5D-3L was considered the gold standard for assessment of criterion validity in accordance with the creation of the original Wound-QoL instrument.20 In retrospect, this may be criticized particularly when evaluating the results of the psychometric properties of criterion validity showing moderate and less moderate values for the 3 domains. In the creation of the CWIS, which is 1 of the instruments used to develop the Wound-QoL, the SF-36 was used as the gold standard, and this instrument also was used for the Swedish validation study of the CWIS.15,19 The SF-36 may perhaps have been a better choice as gold standard because it is more extensive and described problems with ceiling and floor effect of the EQ-5D-3L. This could have had a negative influence on the result because it may have been more problematic to detect changes.31
In addition, the creators of the original instrument acknowledge that having data from their study only from specialist centers with expertise in wound management21 may limit their findings. This is also the case in this validation study of the Swedish version and leaves the generalizability of the result in patients treated in primary care and other nonspecialist wound health care units open for discussion.
Another limitation of this study can be seen in the test-retest assessment of reliability. Most commonly, a follow-up time of approximately 1 week is used for performing this test.24 In this study, the decision was made to use the same follow-up measurement for both test-rest and responsiveness to decrease the burden for the included patients so they just needed to fill in the questionnaires twice. As such, using the EQ-5D-3L items where patients can rate their perceived health status as worsened, unchanged, or improved, the data of the 6-week follow-up could be used for both measurements.
A study to assess the results of translating into Swedish and to validate the wound-specific Wound-QoL showed the instrument has acceptable psychometric properties and is a reliable and valid tool for measuring HRQOL in patients with hard-to-heal wounds in Sweden. Further psychometric studies need to be performed validating the instrument in patient groups with acute wounds, with different wound treatment, and for patients treated in nonspecialized wound clinics such as home care.
The authors thank the Swedish Tissue Viability Nurse Association its valuable contribution to this study.
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Dr. Fagerdahl is a perioperative nurse and researcher, Wound Centre, Södersjukhuset, Department of Clinical Science and Education; and Dr. Bergström is a researcher, Unit of Intervention and Implementation Research for Worker Health, IMM Institute of Environmental Medicine, Karolinska Institutet Södersjukhuset, Stockholm, Sweden. Please address correspondence to: Ann-Mari Fagerdahl, Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet Södersjukhuset, S - 118 83 Stockholm, Sweden; email: firstname.lastname@example.org.