Across-study evaluation of association between steroid dose and bolus steroids and avascular necrosis of bone.

Studies investigating steroid dose and avascular necrosis of bone (AVN) have found either a weak association or none at all. This quantitative review of published studies has evaluated the effects of steroid dose and bolus steroids on the risk of AVN. 22 papers with sufficient information for analysis were identified. The mean steroid dose for the cohort was plotted against the percentage in whom AVN developed. Total dose was divided into non-bolus (oral) and bolus dose, and doses 1, 3, 6, and 12 months after beginning steroids were tested separately for their association with AVN risk. There was a strong correlation between daily total dose and AVN rate (r = 0.61-0.80). Oral dose was strongly correlated with AVN rate (r = 0.70-0.86), but bolus dose was not associated with AVN risk. This strong association between AVN and steroid dose contrasts with the weak relations found in case-control studies from individual centres in which cases and controls received similar steroid regimens and therefore did not differ greatly in steroid dose. The method of deriving a single exposure level per study and comparing the amount of exposure across studies may be useful in assessing whether a drug's toxicity is dose dependent.