A Systematic Review and Meta-Analysis of the Association Between Cold Exposure and Stroke Risk

Background Although evidence of a direct relationship between cold exposure and stroke risk is lacking, cold exposure is generally recognized as a risk factor for stroke. This systematic review and meta-analysis evaluate the relationship between cold exposure and stroke risk and can separate physiological responses to cold temperatures from seasonality confounders while examining these effects in populations vulnerable to cardiovascular disease. Methods Following PRISMA guidelines, a systematic search of PubMed, Scopus, and Web of Science (2000–2024) identified studies investigating "cold exposure," "stroke," and "cardiovascular risk." From 2,178 screened records, 15 observational/experimental studies met inclusion criteria (English, open access, adult populations). Two reviewers independently extracted data and assessed quality using the Newcastle-Ottawa Scale (observational studies) and Cochrane Risk of Bias Tool (experimental studies). A random-effects meta-analysis calculated pooled risk ratios (RRs) and 95% confidence intervals (CIs), stratified by health status (healthy vs. cardiovascular disease), geographic region (Asia vs. Western populations), and critical temperature thresholds. Meta-regression identified 2.9°C as the pivotal threshold for increased stroke risk. Results Although there was no association between cold exposure and stroke risk overall when examining 221,503 individuals (RR: 1.05, 95% CI: 0.92–1.21), stroke risk was elevated among those at risk for cardiovascular disease (RR: 1.52, 95% CI: 1.30–1.77), particularly among hypertensive (RR: 1.68) and atherosclerotic (RR: 1.41) individuals. There were also geographic differences, with stronger associations for Asian populations (RR: 1.23, 95% CI: 1.15–1.30) compared to Western populations (RR: 1.04, 95% CI: 0.98–1.10; P  = 0.01). A critical temperature threshold was 2.9°C, with a 3.5% increased chance of risk associated with a one degree decrease in temperature below 2.9°C ( P  < 0.01). Seasonal risks were associated with comorbidity, decreased activity, and respiratory infections. Conclusion Cold exposure amplifies stroke risk in individuals with cardiovascular disease but is not an independent cause. Public health strategies should prioritize year-round management of hypertension and atherosclerosis over environmental modifications. Clinicians in high-risk regions (e.g., Asia) should address cold-related physiological stressors. These findings advocate for climate-specific interventions and culturally informed cold-weather advisories.