The cold effect of ambient temperature on acute aortic dissection hospital admission: utilizing distributed lag nonlinear analysis

The effects of ambient temperature on acute aortic dissection (AAD) admissions in China have not been well addressed. So, the aim of study was to explore the effect of ambient daily mean temperature for AAD admissions, especially in Hefei, China. Data on daily mean temperature, daily maximum temperature, daily minimum temperature, air pressure, relative humidity and AAD admissions in Hefei were obtained between 2015 and 2020. Distributed lag non-linear model was employed to determine the association between daily ambient temperature and AAD admissions. Relative risk (RR) with 95% confidence interval (CI) were calculated based on gender, age group and hypertensive status. A total number of 1648 AAD admitted cases were documented. A non-linear acute effect of cold temperature on AAD was evaluated. Compared with median reference temperature (17.56 °C), the cumulative RR of extreme low temperature increased the risk of AAD admissions. The cumulative effect was at lag 0 day (RR: 1.639, 95% CI: 1.120, 2.398), and got the peak at lag 3 days (RR: 2.176, 95% CI: 1.345, 3.519). Then the effect size was gradually reduced until lag 8 days (RR: 1.953, 95% CI: 1.010, 3.776). The impact of extreme low temperature on AAD admissions was found to be more obvious in male, the elderly, and hypertensive patients. Overall, exposure to extreme low temperature was associated with increasing AAD daily admissions risk in Hefei, China.