RESUMEN
Bone mass was only previously studied in juvenile dermatomyositis/polymyositis (DM/PM) patients. Therefore, the objective this study was to evaluate the prevalence of osteoporosis and fractures in adult DM/PM. Forty female DM/PM and 78 age-, gender-, and BMI-matched healthy controls were studied. Medical charts and clinical interviews of all patients were evaluated for demographic and clinical data, including disease activity, cumulative doses of glucocorticoid, menarche and menopause age, and fractures. Bone mineral density (BMD) using dual X-ray absorptiometry (DXA) were measured at lumbar spine (L1-L4) and hip. A decreased BMD in lumbar spine [0.902 (0.136) vs. 0.965 (0.141) g/cm(2), P = 0.022] and femoral neck [0.729 (0.12) vs. 0.784 (0.127) g/cm(2), P = 0.027] was observed in patients compared to controls. In addition, osteoporosis was more frequent in patients than in controls in both lumbar spine (20 vs. 3.8%, P = 0.007) and the femoral neck (27.5 vs. 10.3%, P = 0.016). Moreover, a high prevalence of fractures was found in patients in comparison to healthy subjects (17.9 vs. 5.1%, P = 0.040; OR = 3.92; CI 95%:1.07-14.33). Comparing DM/PM patients with (n = 17) and without (n = 23) osteoporosis/fractures, significant differences were observed regarding age [56.8 (11.9) vs. 48.3 (13.2) years, P = 0.042], weight [62.05 (13.56) vs. 71.51 (11.46) kg, P = 0.022] and frequency of post menopausal women (94.1 vs. 65.2%, P = 0.0002). No differences were observed concerning height, lean mass, total fat mass, disease activity, mean value of creatine kinase, cumulative glucocorticoid dose, or bisphosphonate use. Logistic regression analysis revealed a negative association between the presence of osteoporosis/fractures and weight (OR: 0.92, 95% CI: 0.85-0.98; P = 0.016). This is the first study that analyzed bone mass in adult DM/PM patients and it demonstrated that about one quarter of these patients have osteoporosis/fracture.