Low-dose corticosteroids and avascular necrosis of the hip and knee.
BACKGROUND
Although high-dose corticosteroid use constitutes a well-known risk factor for avascular necrosis (AVN), the risk of AVN with low-dose corticosteroids is not well established.


OBJECTIVE
To assess AVN risk for high-dose and low-dose oral corticosteroid exposure compared to baseline risk.


METHODS
We employed a nested case-control study design. AVN of the hip and knee was determined from coded diagnoses and full text record review. Corticosteroid exposure was ascertained through outpatient automated pharmacy dispensing files.


RESULTS
Thirty-one cases occurred during approximately 720,000 person years. Eleven of 22 cases that met all eligibility criteria received oral corticosteroids during the 3 years before diagnosis. There was a cumulative dose-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% Lower CI 26) for doses greater than 1290 mg.


CONCLUSIONS
Systemic corticosteroids were strongly associated with AVN, however, the effect was not clearly evident at 3-year cumulative doses </=430 mg. Copyright (c) 2000 John Wiley & Sons, Ltd.
Bauer
M
M
Harvard Pilgrim Health Care, Watertown, MA, USA.
Thabault
P
P
Estok
D
D
Christiansen
C
C
Platt
R
R