Patterns and predictors of joint damage as assessed by the rheumatoid arthritis articular damage (RAAD) score in South Africans with established rheumatoid arthritis

Abstract

This study aimed to determine the pattern and predictors of joint damage measured by the rheumatoid arthritis articular damage (RAAD) score and to describe its relationship to functional disability in patients with established rheumatoid arthritis (RA). One hundred Black patients with RA of disease duration ≥5 years were studied cross-sectionally. Data collected included socio-demographics, disease duration, smoking, body mass index (BMI), extraarticular features, rheumatoid factor (RF), haemoglobin (Hb), disease activity (DAS28), delay in disease-modifying antirheumatic drug initiation (DMARD lag) and treatment history. As outcome measures, the RAAD score and modified Health Assessment Questionnaire (mHAQ-DI) were used to assess joint damage and disability, respectively. Data were analysed by univariate and multivariate analyses. The mean RAAD score was 28.2 ± 12.8 for a mean disease duration of 17.5 ± 8.5 years. The majority of patients still had active disease (mean DAS28 4.4) and severe disability (mean mHAQ-DI 1.9), reflected in part by a long mean DMARD lag (9 years). Wrist and ankle joints were commonly involved. Multivariate analysis revealed that longer disease duration, higher RF titres and lower BMI were significant independent predictors of a higher RAAD score. The mHAQ-DI was significantly associated with DAS28, RAAD, education and Hb. Our results provide support for aspects of validity of the RAAD score and for its use in under-resourced settings. Further longitudinal studies are needed to evaluate its sensitivity to change in monitoring joint damage. Patterns of joint involvement and the inverse relationship between BMI and joint damage also merit further investigation in Black RA patients.