Incidence of osteonecrosis associated with corticosteroid therapy among different underlying diseases: prospective MRI study.

OBJECTIVES: The purpose of this study was to clarify the incidence of (CS)-associated osteonecrosis among different underlying diseases and to evaluate the risk factors for steroid-associated osteonecrosis in a prospective MRI study.
METHODS: We prospectively used MRI to study 337 eligible underlying disease patients requiring CS therapy and succeeded in examining 1199 joints (hips and knees) in 302 patients with MRI for at least 1 year starting immediately after the onset of CS therapy (1-year follow-up rate of 90%). The underlying diseases included SLE in 687 joints (173 patients) and a variety of other rheumatological disorders in 512 joints (129 patients).
RESULTS: The incidence of osteonecrosis was significantly higher in SLE patients than in non-SLE patients (37 vs 21%, P = 0.001). Logistic regression analysis revealed that adolescent and adult patients had a significantly higher risk of osteonecrosis compared with paediatric patients [odds ratio (OR) = 13.2], that high daily CS dosage (>40 mg/day) entailed a significantly higher risk of osteonecrosis compared with the dosage of <40 mg/day (OR = 4.2), that SLE patients had a significantly higher risk of osteonecrosis compared with non-SLE patients (OR = 2.6) and that male patients had a significantly higher risk of osteonecrosis compared with female patients (OR = 1.6).
CONCLUSION: These findings suggest that the incidence of CS-associated osteonecrosis varies among different underlying diseases.