Seasonal variation in cryptogenic and noncryptogenic hemoptysis hospitalizations in France.

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.