Risk factors for pneumonia in immunocompromised patients with influenza

Abstract

Background: Immunocompromised patients with influenza are at higher risk of pneumonia and death. However, risk factors for progression to pneumonia still need evaluation.

Methods: Retrospective study in immunocompromised patients with influenza-related respiratory infections. Risk factors for pneumonia were identified by multivariable logistic regression.

Results: We identified 100 immunocompromised patients infected with influenza (68 hematological malignancies, 11 HIV, 21 iatrogenic immunosuppression). Immunofluorescence was positive in 95% of patients, mainly on nasopharyngeal aspirates (84%). Influenza A virus was involved in 80% of patients. Associated infection was documented in 34 patients. All patients presented with upper respiratory tract infection and 53 progressed to pneumonia. Thirty-two patients were critically ill, 11 received mechanical ventilation, and 10 died. All the patients who died had pneumonia. Patients with pneumonia were older (46y (36-63) vs. 33y (13-51), P=0.003) and more often had influenza A (89% vs. 70%, P=0.04) and associated infection (56% vs. 9%, P<0.0001). Factors independently associated with progression to pneumonia were influenza A (OR 5.54, 95% CI [1.16-26.47]) and hematological malignancies (OR 3.85, 95% CI [1.1-14.5]).

Conclusions: In our cohort of hospitalized immunocompromised patients, influenza progresses to pneumonia in more than half the patients. Patients with hematological malignancies and influenza A infection are at higher risk for pneumonia and should be included in preemptive antiviral therapy trials.