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A prospective cohort study published in the Journal of the American Heart Association found that ischemic stroke survivors living in areas with higher transportation noise had a higher rate of recurrent stroke, with no corresponding association for initial stroke severity or all-cause mortality. Hely D. Nanavati, PhD, MPH, MBBS, of the University of Michigan, and colleagues drew on the Brain Attack Surveillance in Corpus Christi (BASIC) Project, a population-based stroke surveillance study in Nueces County, Texas.
The analysis included 2441 patients with incident ischemic stroke identified between 2016 and 2023. The cohort averaged 68.4 years of age, 47.5% were female, and 58.7% were Mexican American. Transportation noise was assigned from US Department of Transportation models for 2016 and 2018, which capture roadway and aviation noise, using the maximum area-weighted 24-hour sound level within 100 meters of each patient's home. Median exposure was 45.5 decibels. Stroke severity was measured by the National Institutes of Health Stroke Scale, recurrence through the BASIC surveillance system, and mortality through Texas death certificate linkage.
Patients in higher-noise areas did not differ from others on individual characteristics, but they lived in census tracts with lower median household income and higher levels of fine particulate matter and nitrogen dioxide. Models adjusted for demographics, insurance, education, smoking, alcohol use, stroke severity, and tract-level income, population, and air pollution, and compared patients at the 75th versus 25th percentile of exposure.
Over a median follow-up of 2.2 years, 176 patients (7.2%) had a recurrent stroke. Higher transportation noise was associated with a 36% higher rate of recurrence (hazard ratio, 1.36; 95% CI, 1.01 to 1.82; P = 0.04). Noise was not associated with initial stroke severity (P = 0.14) or with mortality over a median 2.5 years, during which 818 patients (33.5%) died (hazard ratio, 1.08; 95% CI, 0.94 to 1.24; P = 0.26). Sensitivity analyses addressing the noise model's floor effect, exposure year assignment, pandemic-era traffic, early recurrences, and competing risk of death produced similar estimates, though the competing risk analysis did not reach statistical significance.
The authors described the recurrence finding as largely hypothesis-generating given the low event count and confidence interval near the null, and noted that no prior study had examined noise and stroke recurrence. Limitations included modeled rather than measured noise, exclusion of railroad noise, and possible residual confounding from unmeasured social and environmental factors. The authors concluded that transportation noise may be an environmental risk factor for stroke recurrence, underscoring the need for policies addressing noise exposure, and called for replication in larger and more geographically diverse cohorts.
