We aimed to examine the risk factors related to the development of osteoporosis in rheumatoid arthritis (RA) patients and whether there is an association among the changes in bone mineral density (BMD), disease activities (modified DAS28), serum 25-hydroxyvitamin D (25OHD) levels, and disease duration.
There were 110 patients with RA and 110 age- and sex-matched healthy controls who were concurrently studied. All of the patients underwent the following measurements: erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor, and serum 25OHD. Dual-energy X-ray absorptiometry (DEXA) was also used to measure the BMD of the left femur at the time of recruitment. Patients taking vitamin D supplement or corticosteroids were excluded.
The incidences of osteopenia (45.6% vs. 36.4%, P = 0.170) and osteoporosis (33.6% vs. 5.45%, P = 0.000) were higher in the RA patients than in the healthy controls. There was a significant negative correlation between vitamin D levels and DAS28 (r = -0.325, P = 0.001) and a significant positive correlation between vitamin D levels and BMD (r = 0.422, P = 0.000). The multiple regression analysis revealed that 25OHD levels were significantly correlated with disease activity and BMD (F = 11.087, P = 0.000). Stepwise multiple regression analysis showed that serum 25OHD levels were the significant predictors for low BMD and high disease activity (DAS28) in RA patients.
The incidences of osteoporosis and osteopenia were higher in RA patients compared to the age- and gender-matched healthy controls. Low serum 25OHD levels correlate with low BMD and high disease activity in RA patients.