Meteorological parameters and seasonal variations in pulmonary thromboembolism.

Background And Objectives: In recent years, circannual variations in incidence and mortality for venous thromboembolic disease have been demonstrated, with a peak in winter. However, several investigators have observed no seasonal variation in these diseases. The aim of our study was to investigate whether a seasonal variation, in terms of atmospheric pressure, humidity, and temperature, exists for pulmonary thromboembolism.

Method: We retrospectively included 206 patients with a diagnosis of pulmonary embolism (PE) between 1 June 2001 and 31 May 2006.

Results: The highest number of cases in the 5 years concerned occurred in May (29 cases). Although PE occurred most commonly in the spring (72 cases) and autumn (51 cases), the difference was statistically significant (P = .003). There were no case correlations with months and pressure, temperature, or humidity. However, there was a statistically significant positive correlation between case incidence and atmospheric pressure (r = 0.53, P < .0005) and humidity (r = 0.57, P < .0005). In terms of risk factors, seasonal distribution was not statistically significant as regards cases of embolism occurring for surgical or nonsurgical reasons (r = 0.588).

Conclusion: In terms of the relationship between seasons and embolism cases, despite the determination of an insignificant positive correlation, a statistically significant positive correlation was determined between air pressure and humidity and case incidence. There is now a need for further wide-ranging prospective studies including various hematological parameters to clarify the correlation between PE and air pressure.