Background: Invasive pulmonary aspergillosis is increasingly identified as a complication of influenza, termed 'influenza-associated pulmonary aspergillosis' (IAPA).

Aims: To assess the morbidity and mortality of critically ill influenza patients with and without IAPA.

Methods: PubMed, Cochrane Library, Scopus and Embase databases were searched for studies containing comparative data of critically ill influenza patients with IAPA. Primary outcomes were all-cause in-hospital and intensive care unit (ICU) mortality. Secondary outcomes were clinical characteristics; duration of invasive mechanical ventilation (IMV); ICU and hospital length of stay (LOS); and requirement for vasopressor, renal replacement therapy (RRT) and extracorporeal membrane oxygenation (ECMO).

Findings: The incidence of IAPA was 28.8% in 853 critically ill influenza patients, with an overall mortality rate of 33.4%. No differences in age and comorbidities were observed. Patients with IAPA were predominantly male and received chronic corticosteroids. In-hospital (49.2% vs 27.0%; P=0.002) and ICU (46.8% vs 20.8%; P<0.001) mortality rates were higher among patients with IAPA than in patients without IAPA. A greater proportion of patients with IAPA required IMV, and had a prolonged IMV duration (mean 17.3 vs 10.5 days; P<0.001), ICU LOS (mean 26.8 vs 12.8 days; P=0.001) and hospital LOS (mean 38.7 vs 27.0 days; P=0.003). Patients with IAPA had greater disease severity and were significantly more likely to require vasopressor (76.4% vs 57.9%; P<0.001), RRT (45.7% vs 19.1%; P<0.001) and ECMO (25.9% vs 12.8%; P=0.004) support compared with patients without IAPA.

Conclusions: A diagnosis of IAPA in critically ill patients is associated with greater morbidity and mortality. Early recognition and more research are needed to determine better diagnostic and treatment strategies.

Keywords: Characteristics; IAPA; Influenza; Influenza-associated pulmonary aspergillosis; Invasive pulmonary aspergillosis; Outcomes.

Copyright © 2021 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.