Association between type of immunosuppression and the incidence, microbiology and outcomes of ventilator-associated lower respiratory tract infections a retrospective multicenter study

Abstract Purpose Ventilator-associated lower respiratory tract infections (VA-LRTI) are among the most common intensive care unit (ICU)-acquired infections in patients receiving invasive mechanical ventilation (IMV). Immunocompromised patients may have a lower incidence of VA-LRTI when compared to non-immunocompromised patients, but the influence of immunosuppression type on VA-LRTI has not been investigated. Methods Multicenter, international retrospective cohort study in 118 ICUs from 9 countries. Immunocompromised adult patients requiring IMV for > 48 hours were included and followed until ICU discharge (censored at day 28). Patients with hematological malignancies were compared to patients with other types of immunosuppression. The study objectives were to assess the association of the type of immunosuppression with VA-LTRI incidence, microbiology and outcome (ICU mortality, length-of-stay, and duration of IMV). Results Eight hundred fifty-four immunocompromised patients were included (median age 65 years, 57.6% males), including 162 with hematologic malignancies. Patients with hematologic malignancies had a lower 28-day cumulative incidence of VA-LRTI than patients with other types of immunosuppression (13.6% vs. 20.1%, adjusted cause-specific hazard ratio [cHR] 0.60, 95%CI 0.37–0.97), mostly due to a lower incidence of VAP (9.3% vs. 13.9%). The proportion of VA-LTRI cases related to multidrug-resistant bacteria was similar between groups. Occurrence of VA-LRTI was associated with an increased mortality and a longer ICU length-of-stay, but this effect was independent of the type of immunosuppression. Conclusion Patients with hematologic malignancies had a lower 28-day cumulative incidence of VA-LRTI than patients with other types of immunosuppression, mainly due to a lower incidence of VAP.