Association between Low Ambient Temperature and Cardiorespiratory Hospital Admissions in Helsinki, Finland

BACKGROUND AND AIM: The relationship between low ambient temperature and hospital admissions is less studied than between high temperature and hospital admissions. Therefore, this study aimed to investigate the association of daily wintertime temperature with cardiorespiratory hospital admissions in the Helsinki metropolitan area, Finland. METHODS: Daily number of hospital admissions for 2001-2017 was obtained from the national hospital discharge register and weather information from the Finnish Meteorological Institute. Time-series quasi-Poisson regression models were fitted controlling for potential confounders such as time trend, weekday, holiday, air pollution, barometric pressure and an indicator for influenza count. A penalized distributed lag linear model with 21 days of lag was used to estimate the association of daily mean temperature with cause-specific cardiorespiratory hospital admissions, stratified by age-groups (All-ages, 18-64, 65-74 and ≥75), during winter months (December-March). RESULTS:The first and 99th percentiles of daily temperature were -19.6 °C and 11.5 °C respectively. Decreased ambient temperature was associated with increased risk of hospitalization for myocardial infarction in the whole population (Risk Ratio [RR] for 1°C decrease in exposure: 1.015, 95% confidence intervals [CIs]: 1.001-1.030), and in the age group 65-74 (RR: 1.035, 95% CIs: 1.003-1.069). There was also an increased risk of hospital admission for chronic obstructive pulmonary disease (RR: 1.026, 95% CIs: 1.002-1.051) and to lesser extent for respiratory diseases in general (RR: 1.006, 95% CI: 0.995-1.017) in the oldest age (≥75). CONCLUSIONS:Cold increases the need for acute hospital care due to both cardiovascular and respiratory causes during winter months. KEYWORDS: respiratory, cardiovascular, winter, hospital admissions, morbidity, weather