Osteoporosis in Black South Africans With Rheumatoid Arthritis

Background Osteoporosis is a common comorbidity associated with rheumatoid arthritis (RA). The aim of this study was to determine the risk factors and possible predictors of osteoporosis in black patients with RA. Methods A retrospective study of 120 randomly selected RA patients attending an arthritis clinic in Johannesburg, South Africa, was carried out, in which 60 patients were with and 60 without osteoporosis. The demographics, disease activity, American College of Rheumatology (ACR) functional status, treatment, and dual-energy X-ray absorptiometry (DEXA) characteristics were compared. Statistical analysis was performed using SPSS version 25.0 (IBM Corp, Armonk, NY). Bivariate comparisons of demographic factors, disease factors, and T-scores between patients with and without osteoporosis were performed, using two-sided t-tests for continuous variables and chi-squared tests for categorical variables. Possible predictors of osteoporosis were subsequently entered into a multivariate logistic regression model with osteoporosis being the dependent variable. The level of significance for all analyses was set at p < 0.05. Results The median (IQR) age of the overall cohort was 67 (61.0, 72.8) years, the majority (95.5%) were female, of which 97.4% were postmenopausal. The mean disease duration from diagnosis to the DEXA was 8.6 ± 6.2 years. Rheumatoid factor (RF) positivity was 89.2% and anti-cyclic citrullinated peptide (ACCP) positivity was 82.7%. The median (IQR) for disease activity score 28 swollen and tender joint count using the erythrocyte sedimentation rate (DAS-28 ESR) was 3.4 (2.8-4.7) and the median (IQR) for ESR was 41 (22, 64.3) mm/h. There were significantly more patients treated with triple therapy in the no osteoporosis group, 38 (63.3%), than in the osteoporosis group, 21 (35%) (p = 0.00). The ACR functional class was significantly worse in the RA patients with osteoporosis than in the RA patients without osteoporosis [median (IQR), 2 (2, 3) vs 2 (1, 2), (p = 0.03)], respectively. Conclusion This study found that a worse ACR functional class was significantly associated with osteoporosis. In addition, the use of triple therapy had a protective effect. Early recognition of the risk factors for osteoporosis should be sought, with prompt preventative measures, screening, and treatment.