Magnitude and direction of temperature variability affect hospitalization for myocardial infarction and stroke: population-based evidence from Guangzhou, China

Relationships between nonoptimal temperatures and cardiovascular disease (CVD) mortality have been well documented. However, evidence of the association between temperature variability (TV) and CVD morbidity is limited. This study aimed to quantify the risk and burden of CVD-related hospitalization associated with the magnitude and direction of TV. Data on meteorology and population-based hospitalizations for myocardial infarction (MI) and stroke were collected in Guangzhou, China, from 2013 to 2017. Hourly temperature variability (HTV) was measured as the standard deviation of hourly temperature records over specific exposure days. The direction (upward or downward) of HTV was defined as the average daily mean temperature change relative to that of the previous day during the exposure period. Quasi-Poisson regression was applied to assess the impact of HTV after adjusting for the daily mean temperature, and the hospitalization fractions attributable to HTV were calculated. A 1 °C-increase in HTV was significantly associated with a 2.24