Abstract

Symptoms perceived in cold weather reflect physiological responses to body cooling and may worsen the course of a pre-existing disease or precipitate disease events in ostensibly healthy individuals. However, the associations between cold-related symptoms and their health effects have remained unknown. We examined whether cold-related cardiac and respiratory symptoms perceived in cold weather predict future morbidity and mortality. Methods: Cold-related symptoms were inquired in four national FINRISK surveys conducted in 1997, 2002, 2007, 2012 in Finland including altogether 17 040 respondents. A record linkage was made to national hospital discharge and cause-of-death registers. The participants were followed up until the first hospital admission due to a cardiovascular or respiratory disease or death, or until the end of 2015. The individual follow-up times ranged from 0 to 18 years (mean 11 years). The association of cold-related symptoms with morbidity and mortality was examined by Kaplan-Meyer and Cox-regression analyses. Results: Cold-related cardiac [hazard ratio (HR), 1.76 and its 95% confidence interval (95% CI), 1.44–2.15] and combined cardiac and respiratory symptoms [1.50 (1.29–1.73)] were associated with hospitalization due to cardiovascular causes. The respective HRs for admissions due to respiratory causes were elevated for cold-related respiratory [1.22 (1.07–1.40)], cardiac [1.24 (0.88–1.75)] and cardiorespiratory [1.82 (1.50–2.22)] symptoms. Cold-related cardiorespiratory symptoms were associated with deaths from all natural [1.38 (1.11–1.72)], cardiovascular [1.77 (1.28–2.44)] and respiratory [2.19 (0.95–5.06)] causes. Interpretation: Cold weather-related symptoms predict a higher occurrence of hospital admissions and mortality. The information may prove useful in planning measures to reduce cold-related adverse health effects.