Polymyalgia rheumatica (PMR), a benign rheumatic disorder, requires long-term glucocorticoid therapy, which could be associated with osteoporosis. In the present study, we compared bone mineral density (BMD), trabecular bone score (TBS) and frequencies of vertebral fracture (VF) among patients with PMR or rheumatoid arthritis (RA) and controls.
Fifty-three postmenopausal women with PMR aged 50 yr or older were eligible for inclusion in this study. Subjects in RA (n = 106) and control (n = 106) groups were selected by propensity score matching with controlling age, body mass index and use of anti-osteoporotic agents.
The frequency of VF in patients with PMR (30.2%) was significantly higher than those in patients with RA (13.2 %) and controls (13.2%, p = 0.017). The mean TBS of patients with PMR (1.317 ± 0.092) was significantly lower than those of patients with RA (1.336 ± 0.089) and the controls (1.373 ± 0.073, p < 0.001). In receiver operating characteristic analysis for VF in patients with PMR, the area under the curve (AUC) was 0.759 (95% confidence interval [CI] = 0.601-0.918, p < 0.001) for TBS and 0.618 (95% CI = 0.442-0.795, p < 0.001) for L-spine BMD. The AUCs were 0.760 (95% CI = 0.630-0.891, p ≤ 0.001) and 0.767 (95% CI 0.627-0.907, p < 0.001) for femur neck and total hip BMD, respectively. Multivariate analysis identified the factor associated with VF of patients with PMR as a lower TBS (Odds ratio: 0.000, 95% CI: 0.000, 0.754, p = 0.043).
TBS could be a supplementary tool for discriminating osteoporotic fractures in postmenopausal patients with PMR.