Adaptation and validation of the Rheumatoid Arthritis Quality of Life (RAQoL) questionnaire for use in Serbia.

Rheumatoid arthritis (RA) is one of the most prevalent inflammatory rheumatic diseases. As it is a chronic and a lifelong destructive disease, the aim of the treatment is to reduce disability and improve quality of life. The Rheumatoid Arthritis Quality of Life (RAQoL) questionnaire is a patient-reported outcome measure, specific to RA. To adapt and validate the RAQoL for use in Serbia, two translation panels were involved to produce the Serbian RAQoL. After successful translation, face and content validity was determined via cognitive debriefing interviews. The psychometric properties of the questionnaire were examined, including reliability and construct validity, by using the Nottingham Health Profile (NHP) as a comparator scale. The RAQoL was translated successfully and rated as applicable, relevant and comprehensive by respondents. The questionnaire had high internal consistency (alpha = 0.94 at both time points) and test-retest reliability (r = 0.92). Moderately high correlations were found between the RAQoL and physical mobility, pain and energy level sections of the NHP, providing evidence of convergent validity. The RAQoL was able to distinguish between patients grouped by perceived general health, incidence of flare-up and disease severity. The Serbian language version of the RAQoL showed strong evidence of reliability and validity and is recommended for use in clinical trials and routine general practice in RA.