Stroke-Associated Pneumonia Clusters Early After Ischemic Stroke

Key Takeaways

• New pneumonia clustered early among adults hospitalized for acute ischemic stroke at a single hospital in China.
• Dysphagia and clinician-selected early nasogastric tube insertion each had adjusted associations with pneumonia.
• Admission stroke severity, neutrophil-to-lymphocyte ratio, and albumin had significantly nonlinear associations with pneumonia risk.
• Pneumonia was significantly associated with subsequent in-hospital death, ICU transfer, and invasive ventilation when its onset was accounted for.
• Among hospital survivors, pneumonia was associated with longer stays and poorer function at discharge.

New pneumonia after admission for acute ischemic stroke complicates assessment of later hospital events. Hospitalized adults with acute ischemic stroke were evaluated for new pneumonia and subsequent outcomes.

Zhang and colleagues assembled 3,347 consecutive adults in a single-center retrospective neurology cohort at Qianwei Hospital of Jilin Province in Changchun, China in a study published in Frontiers in Neurology. Patients were admitted from January 1, 2019, through June 30, 2025, within seven days of stroke onset; those with pneumonia or active infection at admission were excluded. Stroke-associated pneumonia (SAP) was diagnosed within seven days after admission under Pneumonia in Stroke Consensus criteria: a new or progressive chest infiltrate accompanied by systemic inflammatory and respiratory manifestations. Onset was the first simultaneous fulfillment of those criteria. In-hospital death was the primary endpoint; intensive care unit (ICU) transfer and invasive ventilation were secondary time-to-event endpoints. Cox models switched SAP exposure from absent to present at onset. Separate survivor-only models examined stay duration and poor discharge function, defined as modified Rankin Scale (mRS) 3–5. Investigators also used adjusted pneumonia-risk models, splines, multiple imputation, and complete-case and day-3 landmark checks.

New pneumonia developed in 428 patients (12.8%) within the postadmission ascertainment window. Of pneumonia cases, 55% occurred within 72 hours after admission, with the largest share on day 3. Adjusted pneumonia associations included age, pre-stroke disability, chronic obstructive pulmonary disease (COPD), cardioembolism, dysphagia, and clinician-selected nasogastric tube insertion within 48 hours. Admission National Institutes of Health Stroke Scale (NIHSS) score, neutrophil-to-lymphocyte ratio (NLR), and albumin had significantly nonlinear associations with pneumonia risk. Risk rose more steeply with greater stroke severity and inflammation and lower albumin.

After pneumonia onset was accounted for, SAP was associated with in-hospital death, with an adjusted time-dependent hazard ratio (HR) of 2.34 (95% confidence interval 1.71–3.20). ICU transfer and invasive ventilation also had significant adjusted time-dependent associations with SAP. Among hospital survivors, adjusted mean stay was 35% longer with pneumonia, and odds of poor discharge function were higher in separate survivor-only models. Complete-case and day-3 landmark checks yielded directionally consistent associations for death, ICU transfer, and ventilation.

The single-center retrospective setting limited interpretation. Pneumonia recognition depended on documented symptoms and imaging, and residual confounding remained possible, including from unavailable infarct characteristics. Ventilator-associated pneumonia was included without separate analysis, and follow-up ended in the hospital. Early tube placement reflected clinical decisions influenced by swallowing impairment and stroke severity; its association does not establish tube-related harm. The observed links between pneumonia and later events likewise do not establish causation, and investigators tested no preventive treatment.

Investigators observed early clustering of SAP and associations with later adverse hospital events; longer stays and poorer discharge function were associations observed only among survivors.

Clinician Questions

How was dysphagia defined in the acute ischemic stroke pneumonia cohort?

Swallowing was evaluated with the Kubota water-drinking test within 24 hours of admission. Grades 3–5 on its five-grade scale counted as dysphagia, an assessed baseline characteristic rather than an assigned treatment.

Which patients contributed to the day-3 landmark comparison of stroke-associated pneumonia and hospital outcomes?

Only patients still hospitalized for at least three days were eligible. Pneumonia diagnosed during those first three days became a fixed exposure, and follow-up for subsequent hospital outcomes began on day 3.

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