The role of non-corticosteroid related factors in osteonecrosis (ON) in systemic lupus erythematosus: a nested case-control study of inception patients.

Several factors have been associated with the development of osteonecrosis (ON) in SLE but corticosteroid (CS) therapy has been the most consistent association. We sought to determine factors that predisposed to, or protected from, the development of ON in lupus patients when cumulative oral corticosteroid doses were matched between cases and controls, thereby removing presence of corticosteroid therapy and cumulative dose as risk factors. A nested case-control study of an inception cohort of SLE patients was used to determine the clinical, laboratory and therapeutic differences between patients who developed their first ON event and patients who did not develop ON, having matched these groups for their cumulative oral corticosteroid doses. Of the 570 patients seen within the first year after diagnosis 65 (11.4%) developed ON. None of the variables examined were found to confer additional ON risk in multivariate analysis. It appears that the major factor associated with the development of ON is corticosteroid therapy. Factors which may protect a majority of patients on corticosteroids from developing ON remain to be elucidated.