Body temperature in the acute phase and clinical outcomes after acute ischemic stroke

Abstract

Background: This study aimed to examine whether post-stroke early body temperature is associated with neurological damage in the acute phase and functional outcomes at three months.

Methods: We included 7,177 patients with acute ischemic stroke within 24 h of onset. Axillary temperature was measured daily in the morning for seven days. Mean body temperature was grouped into five quintiles (Q1: 35.1‒36.5°C, Q2: 36.5‒36.7°C, Q3: 36.7‒36.8°C, Q4: 36.8‒37.1°C, and Q5: 37.1‒39.1°C). Clinical outcomes included neurological improvement during hospitalization and poor functional outcome (modified Rankin scale score, 3-6) at three months. A logistic regression analysis was performed to evaluate the association between body temperature and clinical outcomes.

Results: The patient's mean (SD) age was 70.6 (12.3) years, and 35.7% of patients were women. Mean body temperature was significantly associated with less neurological improvement from Q2 (odds ratios [95% confidence interval], 0.77 [0.65-0.99] vs. Q1) to Q5 (0.33 [0.28-0.40], P for trend <0.001) even after adjusting for potential confounders, including baseline neurological severity, C-reactive protein levels, and post-stroke acute infections. The multivariable-adjusted risk of poor functional outcome linearly increased from Q2 (1.36 [1.03-1.79]) to Q5 (6.44 [5.19-8.96], P for trend <0.001). These associations were maintained even in the analyses excluding patients with acute infectious diseases. Multivariable-adjusted risk of poor functional outcome was higher in patients with early body temperature elevation on days 1-3 and with longer duration with body temperature >37.0°C.

Conclusions: Post-stroke early high body temperature is independently associated with unfavorable outcomes following acute ischemic stroke.

Fig 1. Association between BT and neurological courses.

BT: body temperature, CI: confidence interval. Multivariable-adjusted odds ratios (square) and 95% confidence intervals (horizontal bars) of neurological courses in acute phase are shown for Q2-Q5 compared to Q1. The multivariable model included the following covariates: age, sex, hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, previous stroke, body mass index, estimated glomerular filtration rate, early hospital arrival, National Institutes of Health Stroke Scale score on admission, stroke subtype, reperfusion therapy, acute infections, and C-reactive protein level.

Fig 2. Association between BT and clinical outcomes at 3 months.

BT: Body temperature, CI: Confidence interval. Multivariable-adjusted odds ratios (square) and 95% confidence intervals (horizontal bars) of clinical outcome at 3 months are shown for Q2-Q5 compared to Q1. The multivariable model included the following covariates: Age, sex, hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, previous stroke, body mass index, estimated glomerular filtration rate, early hospital arrival, National Institutes of Health Stroke Scale score on admission, stroke subtype, reperfusion therapy, acute infections, and C-reactive protein level.

Fig 3. Associations between the duration of BT and poor functional outcome.

BT: Body temperature, CI: Confidence interval. Multivariable-adjusted odds ratios (square) and 95% confidence intervals (horizontal bars) of poor functional outcome are shown for BT >37.0°C on each day when BT first exceeded 37.0°C (compared to BT ≤37.0°C on respective days, A), and total days of BT of >37.0°C (compared to BT of ≤37.0°C for 7 days after stroke onset, B). The multivariable model included the following covariates: Age, sex, hypertension, diabetes mellitus, dyslipidemia, atrial fibrillation, previous stroke, body mass index, estimated glomerular filtration rate, early hospital arrival, National Institutes of Health Stroke Scale score on admission, stroke subtype, reperfusion therapy, acute infections, and C-reactive protein level.