Decreasing incidence and determinants of Bacterial Pneumonia in people with HIV: The Swiss HIV Cohort Study

BACKGROUND Bacterial pneumonia is one of the leading reasons for hospitalization among people with HIV (PWH), yet there is limited evidence regarding its drivers in the era of potent antiretroviral therapy. METHODS We assessed risk-factors for bacterial pneumonia in PWH enrolled in the Swiss HIV Cohort Study using univariable and multivariable marginal models. We further assessed the relationship between risk-factors and changes in bacterial pneumonia incidence using mediation analysis. RESULTS We included 12927 PWH with follow-ups between 2008 and 2018. These patients had 985 bacterial pneumonia events during a follow-up of 100779 person-years(py). bacterial pneumonia incidence significantly decreased from 13.2 cases/1000 py in 2008 to 6.8 cases/1000 py in 2018. Older age, lower education-level, intravenous drug use, smoking, lower CD4-cell-count, higher HIV-viral load, and prior pneumonia events were significantly associated with higher bacterial pneumonia incidence. Notably, even CD4-cell-counts 350-499 were significantly associated with an increased risk compared to CD4≥500 (adjusted HR,1.39; 95% CI,1.01-1.89). Finally, we found that the decreasing incidence over the last decade can be explained by decreasing proportion of patients with CD4200, and smoking>one cigarette/day. CONCLUSION Improvements in cascade of care of HIV and decrease in smoking may have mediated a substantial decrease in bacterial pneumonia incidence