Effect of Glucocorticoids on Bone Mineral Density in RA Not Modified by Age, Sex

In patients with rheumatoid arthritis (RA), the relationship between glucocorticoids (GCs) and bone mineral density (BMD) does not appear to be affected by age or sex, according to results of a cross-sectional analysis published in Arthritis Research & Therapy.

Although GCs are often used for treatment of RA, long-term use may cause osteoporosis (OP) in some patients.

Researchers sought to analyze the effects of age and sex on the relationship between GCs and BMD among patients with RA. Data were sourced from the Rh-GIOP cohort (Clinicaltrials.gov identifier: NCT02719314), a single-center study of patients with rheumatic diseases receiving treatment with GCs. In analyzing these data, the researchers intended to assist in customizing the treatment of RA in relation to the risk for GC-induced OP.

Inclusion criteria were diagnosis of RA, clinical indications for OP, and previous or current prescription for GCs. Patients taking high-dose GCs that are not typically used for long periods (>15 mg daily of prednisone equivalent) were excluded.

The primary outcome was defined as the minimum T-score of either the lumbar spine, total femur, or femoral neck. Patients’ current GC dose (mg daily of prednisone equivalent) was defined as the main exposure variable. Patients’ cumulative GC dose and cumulative duration of GC use were assessed as secondary exposures.

Linear regression analyses were performed to assess whether age or sex modified the association between GCs and BMD, with adjustments for potential confounders.

The study included a total of 483 patients with RA, of whom 80% were women, and the mean (SD) age was 64 (12) years. Approximately 33% of patients were not currently taking GCs, 32% were taking 5 mg daily (prednisone equivalent), and 11% were taking more than 7.5 mg daily (prednisone equivalent).

Approximately 23% of patients were found to have OP following evaluation with dual-energy x-ray absorptiometry (DXA), where a minimum T-score of -2.5 was used as the cutoff. Roughly 50% of patients sustained nonvertebral fractures prior to enrollment. 

The results of both crude and adjusted models indicated no statistically significant difference in the effect of GCs on BMD between patients aged 65 years and older vs younger than 65 years (P for interaction =.77).

Patient sex was not found to modify the effect of GCs on BMD. Changes in minimum T-scores associated with a 1-mg change in current GC daily dose were similar between men and women (slope, -0.07 and -0.04, respectively; P for interaction =.41).

Results were not significantly affected when cumulative dose and duration of use were used as exposures.

This study is limited by its single-center, observational, and cross-sectional nature. Moreover, it is important to note that BMD is solely a surrogate measure for OP.

According to the researchers, “In summary, this study did not find age and sex to be effect modifiers with regard to the impact of GCs on BMD in patients with RA.”