How much corticosteroid puts a patient at risk for Osteonecrosis?
Overall, 10% to 30% of patients on GCs develop ON. A previous review estimated a 4.6-fold increase in the rate of ON for every 10 mg/day increase in the mean daily dose of prednisone during the first 6 months of therapy. More recent reports suggest that the risk of ON is increased in patients who are on >20 mg/day of prednisone for over a month or receive >2 g total over 2 to 3 months. The risk of ON increases by 5% for every 20-mg increase in prednisone dose . Although controversial, high-dose pulse corticosteroids alone (i.e., 1 g methylprednisolone monthly) does not increase risk unless followed by high-dose daily oral prednisone. Patients who smoke or have systemic lupus erythematosus (SLE), antiphospholipid antibodies, or rapidly develop profound Cushingoid features are particularly likely to develop ON.
