Hospitalizations in a cohort of HIV patients in Australia, 1999-2007

Objectives To describe hospitalization rates, risk factors and associated diagnoses in people with HIV in Australia between 1999 and 2007. Design Retrospective cohort study of people with HIV (n = 842) using data linkage between the Australian HIV Observational Database and administrative hospital morbidity data collections. Methods Incidence rate ratios with 95% confidence intervals were estimated using Poisson regression models to assess risk factors for hospitalization. Predictors of length of stay were assessed using generalized mixed models. The association between hospitalization and mortality was assessed using Cox regression. Results In 4519 person-years of observation, there were 2667 hospital admissions; incidence rate of 59 per 100 person-years. Hospitalization rates were 50–300% higher in this cohort than comparable age and sex strata in the general population. Older age (incidence rate ratio 1.46, 95% confidence interval 1.28–1.65 per 10-year increase) and prior AIDS (incidence rate ratio 1.71, 95% confidence interval 1.24–2.35) were significantly associated with hospitalization. Other predictors of hospitalization included lower CD4 cell counts, higher HIV RNA, longer duration of HIV infection and experience with more drug classes. Lower CD4 cell counts, older age and hepatitis C virus antibody positivity were independently associated with longer hospital stay. Non-AIDS diseases were the principle reason for admission in the majority of cases. Mortality was associated with more frequent hospitalization during the study period. Conclusion Hospitalization rates are higher in people with HIV than the general population in Australia and are associated with markers of advanced HIV disease despite the widespread use of combination antiretroviral therapy.