Incidence and Risk Factors for Invasive Pneumococcal Disease in HIV-infected and non-HIV infected Individuals Before and After the Introduction of Combination Antiretroviral Therapy: Persisting High Risk among HIV-infected Injecting Drug Users

BACKGROUND:  Invasive pneumococcal disease (IPD) is an important cause of morbidity among HIV-infected individuals. We described incidence and risk factors for IPD in HIV-infected and uninfected individuals.

METHODS:  Nationwide population-based cohort study of HIV-infected adults treated at all Danish HIV-treatment centers during 1995-2012. Nineteen population-matched controls per HIV-infected individual were retrieved. The risk of IPD (RR, [95% CI]) was assessed using Poisson regression.

RESULTS:  The incidence of IPD was 304.7 cases/100,000 PYFU in HIV-infected and 12.8/100,000 PYFU in HIV-uninfected individuals. After adjusting for confounders, HIV-infection (RR 24.4 [23.7-25.1]), male sex (RR 1.20 [1.16-1.24]), increasing age (per year) (RR 1.03 [1.03-1.04]) and calendar period (pre-cART [RR 2.80 [2.70-2.91] compared to late cART) were significantly associated with an increased risk of IPD. Among HIV-infected individuals, male sex (RR 1.57 [1.49-1.66]), smoking (RR 1.34 [1.26-1.42]), and intravenous drug use (RR 2.51 [2.26-2.67]) were associated with an increased risk of IPD. Detectable viral loads (RR 1.88 [1.79-1.98]) and a relative fall in CD4 T-cell counts were also associated with an increased risk (≥500 to 350-<500 CD4 T-cells/µl RR 1.29 [1.21-1.37], and <100 cells/µl RR 7.4 [6.87-8.02]). The risk of IPD declined over time though this was not the case for IDUs where the risk remained unchanged.

CONCLUSIONS:  The incidence of IPD in HIV-infected individuals remained significantly higher than the incidence observed in non-HIV-infected, in spite of the widespread use of cART. IDUs have a persisting high risk of IPD. IDU, smoking, the receipt of cART are suitable targets for preventive measures in the future.