Extreme and moderate temperatures and risk of hospitalizations for pulmonary hypertension: an 11-year time-series study in Shanghai, China

Background Although ambient temperature is known to influence hospitalizations for respiratory diseases, none has focused specifically on pulmonary hypertension (PH) hospitalizations. Methods Using an 11-year dataset (2013–2023) from Shanghai, China, we performed a time-series analysis to assess the impact of daily temperature on PH-related hospitalizations. A distributed lag non-linear model was applied to examine both the immediate (single-day) and prolonged (cumulative) effects of temperature exposure over a lag period of up to 30 days. Cumulative risk estimates were used to assess overall impact of specific temperature exposures by calculating the relative risk (RR) of PH hospitalizations. We also plotted exposure-response curves. Stratification analyses were conducted by age, sex, and medical insurance status to identify potentially vulnerable subpopulations. Results Over the study period, a total of 12,218 hospitalizations for PH were recorded. We observed a non-linear, U-shaped relationship between daily mean temperature and PH hospitalization risk. Specifically, cold extremes, including extreme cold (5th percentile of daily average temperature, 4.6 °C) and moderate cold (25th percentile of daily average temperature, 10.4 °C) were significantly linked to increased risk, while no significant associations were observed for heat extremes. Compared with the reference temperature (18 °C), extreme cold showed the strongest effect, with a single-day lag effect peaking at lag 3 (RR: 1.05, 95% CI: 1.01–1.10) and a cumulative effect over lag 0–30 days (RR: 2.80, 95% CI: 1.19–6.59). The attributable fractions of PH hospitalization were 8% for extreme cold and 26% for moderate cold. Stratified analyses revealed higher susceptibility among females, younger individuals (<65 years), and those without medical insurance. Conclusion This study provides novel epidemiological evidence that cold exposure significantly increases the risk of PH hospitalization, with particularly pronounced effects observed among females, individuals aged < 65 years, and those without medical insurance.