Study objective: To determine the potential role of seasonality in hospitalizations for cryptogenic and noncryptogenic hemoptysis in the French population.
Design: Retrospective analysis of hospital discharge data from a National Register.
Setting: All 29 French university hospitals, between July 1, 1994, and June 30, 1997.
Patients: Two thousand six hundred seventy-seven and 3,672 adult hospitalizations for cryptogenic and other hemoptysis, respectively.
Measurements: Cumulative monthly averages were determined, expressed as the percentage above or below the average monthly value during the entire study period.
Results: The distribution of cumulative monthly hospitalizations for cryptogenic hemoptysis peaked in March (32% above the average) and was lowest in summer (30% below the average; p < 0.001). Hospitalizations for noncryptogenic hemoptysis followed a similar seasonal pattern (p < 0. 001). In the 16- to 34-year-old individuals, cryptogenic hemoptysis, compared with noncryptogenic hemoptysis, showed a higher incidence with a larger seasonal amplitude (p < 0.001).
Conclusions: A better understanding of the fundamental pathophysiologic mechanisms underlying this respiratory and hemorrhagic condition may be helpful in developing preventive measures, especially in patients with a risk of recurrence.