Table 2_Elevated platelet-to-lymphocyte ratio is associated with stroke-associated pneumonia in acute ischemic stroke: a retrospective cohort study.docx

Multivariable logistic regression, generalized additive modeling (GAM), and two-piecewise logistic regression were used to examine associations between PLR and stroke-associated pneumonia (SAP). Subgroup analyses were performed across seven clinical variables with interaction tested by likelihood ratio test. Predictive performance was evaluated by receiver operating characteristic (ROC) analysis and compared with C-reactive protein (CRP) and A2DS2 score using the DeLong test.</p>Results<p>SAP occurred in 359 patients (20.6%).

PLR was higher in patients with SAP than in those without SAP (median 136.17 vs. 113.69, p < 0.001). In the fully adjusted model, log2-PLR remained associated with SAP (OR = 1.36 per 1-unit increase, 95% CI: 1.12–1.65, p = 0.0021). Compared with the lowest quartile, the highest PLR quartile was associated with increased SAP odds (OR = 1.62, 95% CI: 1.03–2.54, p = 0.0386).

GAM and two-piecewise regression identified a threshold at PLR = 224.8 (log2-PLR = 7.812). Below this threshold, the association was not significant (OR = 1.21, 95% CI: 0.93–1.57, p = 0.1551), whereas above it the association was significant (OR = 2.06, 95% CI: 1.10–3.87, p = 0.0240). The AUCs were 0.584 for PLR, 0.825 for CRP, and 0.757 for A2DS2.

The AUCs of the PLR + CRP and PLR + A2DS2 models were 0.803 and 0.763, respectively.</p>Conclusion<p>Elevated PLR is associated with SAP in AIS patients, exhibiting a non-linear threshold-dependent relationship. Although standalone discriminatory performance is modest, PLR is universally available from routine blood counts and may serve as a cost-effective tool for early SAP risk stratification. Prospective multicenter validation is warranted.</p>