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Predictive Value of FT3/FT4 and Neutrophil-to-Lymphocyte Ratios for Post-Ischemic Stroke Urinary Tract Infection and
Zhangyan Geng1, Chun Wang2, Na Li3
1Department of Neurology, The First Hospital of Hebei Medical University, Shijiazhuang, China.
Background:
Urinary tract infection (UTI) is a common complication after acute ischemic stroke (AIS) and is associated with delayed neurological rehabilitation. However, joint biomarkers that reflect stroke-related neuroendocrine-immune dysregulation remain insufficiently defined, and the association between UTI and longitudinal functional recovery has not been fully characterized.
Methods:
This retrospective cohort study included 122 patients with AIS. Baseline clinical parameters, free triiodothyronine to free thyroxine (FT3/FT4) ratios, and neutrophil-to-lymphocyte ratios (NLR) were collected. Multivariate logistic regression was used to identify independent risk factors for UTI. The incremental predictive value of combined biomarkers was evaluated using the area under the receiver operating characteristic curve (AUC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI). A Generalized Estimating Equations (GEE) model was utilized to analyze the longitudinal repeated-measure modified Rankin Scale (mRS) scores at admission, 28 days, and 180 days.
Results:
Among the 122 patients, 33 (27.0%) developed UTI. In the primary multivariable model, a high NLR (≥ 3.78) and a low FT3/FT4 ratio (≤ 0.31) were associated with increased UTI risk. The combined model significantly improved the predictive performance over the baseline clinical model (AUC increased from 0.735 to 0.842, DeLong test p = 0.016), with a continuous NRI of 0.635 (p < 0.001) and an IDI of 0.188 (p < 0.001). Furthermore, the GEE model identified a significant time × group interaction (p = 0.014), indicating that UTI was associated with a slower longitudinal functional recovery trajectory. Post-stroke UTI was associated with poor 180-day functional outcome in the primary outcome model (adjusted OR = 3.28, 95% CI: 1.15-9.32, p = 0.026).
Conclusions:
The combination of baseline FT3/FT4 ratio and NLR provides incremental predictive value for post-ischemic stroke UTI. Furthermore, UTI was associated with a less favorable 6-month functional recovery trajectory, supporting early risk stratification and prevention-oriented management.