Impact of Neutropenia on Clinical Outcomes in Critically Ill Patients with Acute Respiratory Failure

Neutropenia is a common clinical condition in critically ill patients and may be associated with poor outcomes, particularly in the context of acute respiratory failure (ARF). However, evidence on its prognostic impact remains inconsistent, and there are a lack of data, particularly in noncancer and immunocompetent populations. This study evaluates the association between neutropenia and mortality in critically ill patients with ARF and identifies risk factors for mortality among patients with neutropenia.

In this retrospective cohort study, 2412 adult patients with ARF admitted to the intensive care unit (ICU) of a tertiary center between January 2019 and December 2023 were analyzed. Neutropenia was defined as an absolute neutrophil count < 1.5 × 10⁹/L at ICU admission. The primary outcome was hospital mortality; secondary outcomes included ICU mortality. Multivariable Cox proportional hazards models were used to assess the association between neutropenia and outcomes. Subgroup analyses and risk factor assessments were conducted among patients with neutropenia.

Among the 2412 patients, 411 (17.0%) had neutropenia at ICU admission. Compared with their counterparts without neutropenia, patients with neutropenia had higher ICU mortality (48.0% versus 18.9%, P < 0.001) and hospital mortality (60.1% versus 28.3%, P = 0.007). Neutropenia remained independently associated with increased ICU (adjusted hazard ratio [HR] 1.48; 95% confidence interval [CI], 1.20-1.83) and hospital mortality (adjusted HR 1.27; 95% CI 1.07-1.52). The association was more pronounced in patients without cancer (adjusted HR 3.08) than in patients with cancer (adjusted HR 1.48; P for interaction < 0.001). Among patients with neutropenia, sequential organ failure assessment (SOFA) score was an independent predictor of hospital mortality (adjusted HR 1.15; 95% CI 1.11-1.20; P < 0.001).

Neutropenia at ICU admission is independently associated with increased mortality in patients with ARF, particularly among those without cancer. SOFA score is a strong prognostic indicator among patients with neutropenia. These findings highlight the need for improved risk stratification, and suggest that patients with neutropenia may benefit from specific management strategies, which should be investigated in future studies.