Community-acquired pneumonia represents the most frequent bacterial infection in patients with HIV/AIDS. Purpose We aimed to assess variables associated with lower respiratory tract infection (LRTI) among HIVinfected adults using ART. Methods A cohort study of HIV-infected patients aged ≥18 years, enrolled from 2000 to 2015, on ART for at least 60 days, with primary outcome as the 1st episode of LRTI during follow-up. The independent variables included were sex at birth, age, race/skin color, educational level, tobacco smoking, alcohol use, cocaine use, diabetes mellitus, CD4 count, HIV viral load, infuenza and pneumococcal vaccination. Extended Cox proportional hazards models accounting for time-updated variables were ftted to assess LRTI predictors. Results 2669 patients were included; median followup was 3.9 years per patient. LRTI was diagnosed in 384 patients; incidence rate was 30.7/1000 PY. In the unadjusted Cox extended models, non-white race [crude hazard ratio (cHR) 1.28, p = 0.020], cocaine use (cHR 2.01, p < 0.001), tobacco smoking (cHR 1.34, p value 0.007), and HIV viral load ≥400 copies/mL (cHR 3.40, p < 0.001) increased the risk of LRTI. Lower risk of LRTI was seen with higher educational level (cHR 0.61, p < 0.001), rise in CD4 counts (cHR 0.81, p < 0.001, per 100 cells/mm3 increase), infuenza (cHR 0.60, p = 0.002) and pneumococcal vaccination (cHR 0.57, p < 0.001). In the adjusted model, aHR for CD4 count was 0.86, for cocaine use 1.47 and for viral load ≥400 copies 2.20. Conclusions LRTI has a high incidence in HIV-infected adults using ART. Higher CD4 counts and undetectable viral loads were protective, as were pneumococcal and infuenza vaccines.2018-06-30