Risk factors for pneumonia in immunocompromised patients with influenza

Summary 

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.

Keywords: Influenza, Acute respiratory failure, Pneumonia, Bone marrow transplantation, Lymphoma, Bronchoscopy

Abbreviations: ARDS, acute respiratory distress syndrome, BAL, bronchoalveolar lavage, CI, confidence interval, CT, computed tomography, HIV, human immunodeficiency virus, HSCT, hematopoietic stem cell transplantation, ICU, intensive care unit, MDCK cells, Madin–Darby canine kidney cells, NPA, nasopharyngeal aspirates, OR, odds ratio, SAPSII, simplified acute physiologic score II, URTI, upper respiratory tract infection