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Competing risk adjustment reduces overestimation of opportunistic infection rates in AIDS
1Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110, USA. yany@msnotes.wust.edu
Abstract:
To illustrate the importance of adjusting the estimates of cumulative incidence of acquired immunodeficiency syndrome (AIDS) related illnesses for competing risk of other causes of death, we compared unadjusted and adjusted (for competing events) incidence estimates for four AIDS illnesses: pneumocystis cavinii pneumonia (PCP), mycobacterium avium complex (MAC), cytomegalovirus (CMV), and esophageal candidiases. The study population was patients followed by the Johns Hopkins Hospital AIDS Service between 1989 to 1995. Ratios of 4 year unadjusted incidence estimates to 4 year adjusted incidence estimates for the four diseases ranged from 1.38 to 1.86, corresponding to cumulative death rates of 61% to 69%. For CMV, the ratios of 4 year unadjusted to adjusted incidence estimates for five groups of patients ranged from 1.5 to 2.33, corresponding to cumulative death rates of 48% to 78%. We conclude that ignoring the competing risk of death can result in substantial overestimation of disease occurrence, which may give misleading results in estimating and comparing the occurrence of a disease of interest.
Insights
Adjusting for other causes of death is crucial when estimating acquired immunodeficiency syndrome (AIDS) related illnesses. Ignoring competing risks leads to overestimating disease occurrence and potentially misleading comparisons.
Area of Science:
- Epidemiology
- Biostatistics
Background:
- Estimating the cumulative incidence of acquired immunodeficiency syndrome (AIDS) related illnesses requires careful consideration of competing risks.
- Other causes of death can significantly impact the observed incidence rates of specific AIDS-defining conditions.
Purpose of the Study:
- To highlight the importance of adjusting incidence estimates for competing risks of mortality.
- To compare unadjusted and adjusted incidence estimates for four key AIDS-related illnesses.
Main Methods:
- Retrospective cohort study of patients at Johns Hopkins Hospital AIDS Service (1989-1995).
- Calculated unadjusted and adjusted cumulative incidence estimates for pneumocystis pneumonia (PCP), mycobacterium avium complex (MAC), cytomegalovirus (CMV), and esophageal candidiasis.
- Analyzed ratios of unadjusted to adjusted estimates and corresponding cumulative death rates.
Main Results:
- Ratios of 4-year unadjusted to adjusted incidence for four AIDS illnesses ranged from 1.38 to 1.86 (cumulative death rates: 61%-69%).
- For cytomegalovirus (CMV), ratios ranged from 1.5 to 2.33 across patient groups (cumulative death rates: 48%-78%).
- Substantial overestimation of disease occurrence was observed when competing risks were ignored.
Conclusions:
- Failure to account for competing risks of death leads to significant overestimation of AIDS-related disease incidence.
- Adjusted estimates are essential for accurate assessment and comparison of disease occurrence in populations with high mortality rates.
- Misleading conclusions regarding disease prevalence and risk can arise from unadjusted analyses.