The effect of low dose methotrexate on bone density

Objective. High dose methotrexate (MTX) has been linked with bone loss in o ncology patients. However, it is unclear whether longterm low dose MTX used in the treatment of inflammatory arthritis is associated with bone loss. W e compared the effect of low dose MTX on bone density in prospectively recr uited patients with rheumatoid arthritis (RA) and psoriasis/psoriatic arthr itis (Ps/PsA). Methods. Thirty RA patients and 30 Ps/PsA patients taking MTX were compared to controls not taking MTX (30 with RA, 27 Ps/PsA). Bone mineral density ( BMD) of the radius, lumbar spine. trochanter, and femoral neck was measured using Lunar dual energy x-ray absorptiometry. Student t tests were used to detect differences in bone density (using Z scores) of the MTX group versu s controls for both the RA and Ps/PsA groups. Analysis of covariance was us ed to examine for confounders including disease duration, disease activity, age, and sex. Results. BMD of the radius/femoral neck/trochanter did not differ significa ntly between the MTX treated groups and controls when analyzed by Z scores. The mean difference between the MTX group and controls of the femoral neck was 0.040 (95% CI-0.40, 0.12) and 0.060 (95% CI-0.30, 0.15) for the RA and Ps/PsA groups, respectively. The absolute BMD of the lumbar spine (L2-L4) was higher in the RA MTX group than in controls. Analysis of covariance did not reveal an effect of study group on bone density. Conclusion. This study suggests that low dose MTX does not have a negative effect on bone density, at either cortical or trabecular sites.