Background - Although high-dose corticosteroid use constitutes a well-known
risk factor for avascular necrosis (AVN), the risk of AVN with low-dose co
rticosteroids is not well established.
Objective - To assess AVN risk for high-dose and low-dose oral corticostero
id exposure compared to baseline risk.
Methods - We employed a nested case-control study design. AVN of the hip an
d knee was determined from coded diagnoses and full text record review. Cor
ticosteroid exposure was ascertained through outpatient automated pharmacy
dispensing files.
Results - Thirty-one cases occurred during approximately 720,000 person yea
rs. Eleven of 22 cases that met all eligibility criteria received oral cort
icosteroids during the 3 years before diagnosis. There was a cumulative dos
e-related corticosteroid effect from no excess risk (relative risk = 0, 95%
Confidence Interval = 0-5) for doses 1-430 mg, to a relative risk of 6 (95
% CI 1-43) for doses of 440-1290 mg, and an undefined relative risk (95% Lo
wer CI 26) for doses greater than 1290 mg.
Conclusions - Systemic corticosteroids were strongly associated with AVN, h
owever, the effect was not clearly evident at 3-year cumulative doses less
than or equal to 430 mg. Copyright (C) 2000 John Wiley & Sons, Ltd.