[Health related quality of life assessment in patients with systemic sclerosis]

Common measure of quality of life for people with systemic sclerosis across seven European countries: a cross-sectional study

Objectives

The aim of this study was to adapt the Systemic Sclerosis Quality of Life Questionnaire (SScQoL) into six European cultures and validate it as a common measure of quality of life in systemic sclerosis (SSc).

Methods

This was a seven-country (Germany, France, Italy, Poland, Spain, Sweden and UK) cross-sectional study. A forward–backward translation process was used to adapt the English SScQoL into target languages. SScQoL was completed by patients with SSc, then data were validated against the Rasch model. To correct local response dependency, items were grouped into the following subscales: function, emotion, sleep, social and pain and reanalysed for fit to the model, unidimensionality and cross-cultural equivalence.

Results

The adaptation of the SScQoL was seamless in all countries except Germany. Cross-cultural validation included 1080 patients with a mean age 58.0 years (SD 13.9) and 87% were women. Local dependency was evident in individual country data. Grouping items into testlets corrected the local dependency in most country specific data. Fit to the model, reliability and unidimensionality was achieved in six-country data after cross-cultural adjustment for Italy in the social subscale. The SScQoL was then calibrated into an interval level scale.

Conclusion

The individual SScQoL items have translated well into five languages and overall, the scale maintained its construct validity, working well as a five-subscale questionnaire. Measures of quality of life in SSc can be directly compared across five countries (France, Poland Spain, Sweden and UK). Data from Italy are also comparable with the other five countries although require an adjustment.

Predictors of health-related quality of life and fatigue in systemic sclerosis: evaluation of the EuroQol-5D and FACIT-F assessment tools

This study evaluates predictors of health-related quality of life (HRQoL) and fatigue in systemic sclerosis (SSc) using two novel self-report indices. A cross-sectional study of patients with SSc was undertaken using a postal questionnaire including the EuroQol-5Domain health questionnaire (EQ-5D™), Functional Assessment of Chronic Illness Therapy-Fatigue scale (FACIT-F) and the Scleroderma Health Assessment Questionnaire (SHAQ). The EQ-5D assesses five domains of health quality and is quantified as a time trade-off (TTO) value and patient global assessment (0-100 visual analogue scale [VAS]). The FACIT-F is a 13-item questionnaire (0-52 scale). Higher scores for both the EQ-5D and FACIT-F indicate better health. Case notes were scrutinised for patient demographics, disease duration, serology and clinical phenotype. Sixty-eight patients (60 females, mean age 62.6 years) completed the questionnaires. Fatigue correlated closely with HRQoL (r (s) = 0.78 and 0.77 for FACIT-F vs. EQ-5D VAS and TTO respectively, p < 0.01) and disability (r (s) = -0.74 for FACIT-F vs. HAQ-DI, p < 0.01). Pain was the most frequently reported health problem (80 %) in the EQ-5D. HRQoL also correlated closely with disability (r (s) = 0.83 for EQ-5D vs. HAQ-DI, p < 0.01). SHAQ-VAS scores correlated well with the FACIT-F, EQ-5D and HAQ-DI scores (p < 0.05 for all comparisons). Of the patient demographics and clinical disease associations, only the absence of upper gastrointestinal complications was associated with better levels of fatigue, HRQoL and function. There is a strong correlation between disability, fatigue and HRQoL measured using self-reports, possibly reflecting similarly perceived health beliefs amongst patients across outcomes. There was little association between self-report indices and patient demographics and/or clinical phenotype.