Lower peak expiratory flow rate is associated with a higher risk of pneumonia in patients with stroke.

Background: Low peak expiratory flow (PEF) rate is common in patients with stroke. Studies on changes in PEF rates in patients with stroke often have small sample sizes, limiting the generalizability of their findings.

Aim: This study aimed to compare the PEF rates between patients who were post-stroke with or without pneumonia and age- and sex-matched healthy controls and explore the PEF-pneumonia association among stroke survivors.

Design: Prospective observational study.

Setting: Department of Rehabilitation, the First Affiliated Hospital of Wenzhou Medical University.

Population: Initially, 809 patients with stroke undergoing inpatient rehabilitation were recruited.

Methods: Data collected included the demographics, stroke history, the presence of dysphagia, and the PEF rates on admission. Logistic regression analysis was conducted to identify the PEF threshold as predictive of pneumonia after adjusting for confounders.

Results: Patients with stroke had a mean PEF rate of 243.89±139.38 L/min, significantly lower than that of the normal control group. The PEF rate was significantly lower in the pneumonia group than in the non-pneumonia group (P<0.001). Within the stroke cohort, the PEF rates were lower than the predicted rates (P<0.001). Older age, lower PEF(%),and dysphagia were associated with a higher pneumonia risk post-stroke per stepwise multivariate logistic regression analysis. Furthermore, the combination of these three significant predictors (PEF(%), swallowing function, and age) yielded an area under the curve of 0.857 .Regarding age, the cut-off point of ≥65.5 years was the optimal level to discriminate the presence of pneumonia among patients with stroke. For PEF%,the cut-off point of <60% was the optimal level to discriminate the presence of pneumonia among patients with stroke. For screening dysphagia, the patients with impaired safety only and those with impaired safety and efficacy faced a higher pneumonia risk.

Conclusions: Patients with stroke exhibited significantly lower peak expiratory flow rates compared to healthy controls after adjusting for age and sex and when compared to their reference values. Decreased PEF rates were independently associated with pneumonia development during inpatient rehabilitation in post-stroke patients.

Clinical rehabilitation impact: This study suggests that low PEF rates may predict pneumonia and that the prevention of PEF rate decline may prevent pneumonia development.