Prevalence of spondyloarthritis in Serbia: a EULAR endorsed study

Translation, cross-cultural adaptation and psychometric evaluation of the Serbian Ankylosing Spondylitis Quality of Life (ASQoL) Questionnaire (refers to r-axSpA) and its relations with disease activity and functional status indices

OBJECTIVES

To translate, cross-culturally adapt and validate the Serbian Ankylosing Spondylitis Quality of Life (ASQoL) questionnaire, e.g. according to the new nomenclature Radiographic-Axial Spondyloarthritis (r-axSpA), and to relate it to disease activity and functional status domains.

METHODS

Four stages were accomplished: (1) Bilingual and lay panel for translation and cross-cultural adaptation (2) Cognitive debriefing interviews (assessing the language and cultural equivalence of the concepts used in the Serbian ASQoL translation) for face and content validity (3) Psychometric evaluation: (a) convergent validity by NHP as a comparator scale and (b) known group validity by correlations with disease activity and overall health status and reliability (internal consistency and test-retest reliability) (4) Independent regression analyses for relations between ASQoL and ASDAS, BASDAI, BASFI, Schober's test, respiratory index and SPARCC were used. The statistical program SPSS (version 21; IBM, Armonk, NY, USA) was used.

RESULTS

The bilingual panel made a unified version of the translated documents, a lay panel confirmed the clarity of the questionnaire. Cognitive debriefing interviews with 10 patients evaluated the Serbian ASQoL as clear, precise, easy to complete. The psychometric properties with 60 randomly selected patients showed good convergent validity between ASQoL and NHP domains of pain (r = 0.79), emotional reactions (r = 0.78), physical activity (r = 0.77) and energy (r = 0.75). The internal reliability was 0.95 and 0.91 (1st and 2nd administration), respectively, and the test-retest reliability was 0.84. Regression analyses showed highly significant relationships (p < 0.001) between ASQoL and ASDAS (R²=0.403), BASDAI (R²=0.564) and BASFI (R²=0.444).

CONCLUSION

The Serbian ASQoL demonstrated good psychometric properties and significant relationships with disease activity and functional status and is recommended for quality of life assessment in Serbian-speaking ankylosing spondylitis (radiographic axial spondyloarthritis) patients, both in clinical practice and clinical research.

Rheumatoid arthritis and spondyloarthritis prevalence in four European countries - a comparative study

Introduction/Objective. The objective was to compare rheumatoid arthritis (RA), spondyloarthritis (SpA) and subtypes of SpA prevalence in four European countries. Methods. A 33-items detection questionnaire, containing self-reported diagnosis, classification criteria for RA and SpA, personal and family history, was translated using cross-cultural adaptation and validated in France, Turkey, Lithuania and Serbia, where it was used on a population sample. Suspected cases were evaluated and confirmed by a rheumatologist. Prevalence estimates were age- and sex-standardized to European standard population. Results. In total, 33,454 people older than 18 years were screened and 31,454 interviewed: France 14,671, Lithuania 6,558, Serbia 6,213, Turkey 4,012. Standardized RA prevalence varied from 0.29% (95% CI: 0.17?0.40) in France to 0.57% (0.31?0.84) in Turkey; this inequality was mostly caused by differences in women prevalence (from 0.42% in France to 1.02% in Turkey) SpA prevalence was similar in France (0.30%), Serbia (0.35%) and Turkey (0.37%), but in Lithuania it was 0.89%, which could be caused by geographic and genetic differences, as SpA prevalence was higher in North and East Europe, as well as the human leukocyte antigen B27 presence. SpA prevalence was equally presented by gender for France and Serbia. Regarding SpA subtypes, ankylosing spondylitis prevalence varied from 0.07?0.30% (Serbia?Lithuania), PsA 0.10?0.26% (France?Lithuania), reactive arthritis was 0.09?0.18% (Serbia?Lithuania). Previously nondiagnosed SpA cases were found in 6.9% in France, 25.9% in Lithuania and 31.2% in Serbia. Conclusion. East?West decreasing tendency for the female RA prevalence was noted. SpA was higher in North-Eastern Europe than in its Western and Southern part. One quarter of the SpA patients in Lithuania and one third in Serbia were not previously diagnosed. The SpA population prevalence was higher than expected and similar to RA.