A comparison of ad hoc methods to account for non-cancer AIDS and deaths as competing risks when estimating the effect of HAART on incident cancer AIDS among HIV-infected men

Abstract

Objective To compare three ad hoc methods to estimate the marginal hazard of incident cancer acquired immune deficiency syndrome (AIDS) in a highly active antiretroviral therapy (1996–2006) relative to a monotherapy/combination therapy (1990–1996) calendar period, accounting for other AIDS events and deaths as competing risks. Study Design and Setting Among 1,911 human immunodeficiency virus (HIV)-positive men from the Multicenter AIDS Cohort Study, 228 developed cancer AIDS and 745 developed competing risks in 14,202 person-years from 1990 to 2006. Method 1 censored competing risks at the time they occurred, method 2 excluded competing risks, and method 3 censored competing risks at the date of analysis. Results The age, race, and infection duration adjusted hazard ratios (HRs) for cancer AIDS were similar for all methods (HR ≈ 0.15). We estimated bias and confidence interval coverage of each method with Monte Carlo simulation. On average, across 24 scenarios, method 1 produced less-biased estimates than methods 2 or 3. Conclusions When competing risks are independent of the event of interest, only method 1 produced unbiased estimates of the marginal HR, although independence cannot be verified from the data. When competing risks are dependent, method 1 generally produced the least-biased estimates of the marginal HR for the scenarios explored; however, alternative methods may be preferred.