Effect of Climatic Factors on the Seasonal Fluctuation of Pulmonary Embolism

Hospital admissions for pulmonary embolism were identified based on the primary diagnosis. The central adjudication committee at Peking Union Medical College Hospital (Beijing, China) reviewed all medical and death records and determined the final diagnosis. Two adjudication committee members verified events independently, and discrepancies were resolved by discussion involving additional committee members.For each admission, we extracted data on the date of admission, sex, age, and location of the patient from hospital information system.

All the data of daily meteorological variables for the same period, including temperature variables (°C) (the min, max and mean temperature), relative humidity (%), air pressure (hPa), precipitation (mm), wind speed (m/s) and sunshine duration (h), were collected from the China Meteorological Data Sharing Service System (http://www.escience.gov.cn/metdata/page/index.html). The data on PM2.5 levels in each city was collected from the National Air Pollution Monitoring System.

An overdispersed generalised additive model was used to estimate associations between climatic factors and pulmonary embolism admissions. A distributed lag non-linear model (DLNM) was employed to examine their lagged effects.

Inclusion criteria

• Males and females.
• With a primary diagnosis of pulmonary embolism based on clinical symptoms, with or without radiologic features.

Exclusion criteria

• Lack of important data.