Amaç: KOAH'a bağlı hospitalizasyonlarda mevsimsel değişme olup olmadığını belirlemek. Yöntem: 1987-1998 yılları arasında, göğüs kliniğine yapılan 3617 yatıştan, verileri elde edilen 3089 olgu değerlendirildi. Bulgular: Tüm olguların 397'si (%12.9) KOAH olarak sınıflandırılmıştı (kronik bronşit, amfizem, ICD9: 490-492 ve başka yerde sınıflandırılmayan KOAH, ICD9: 496). Aylara göre KOAH'lı hasta sayısı, toplam yatan hasta sayısına göre standardize edildi ve standardize verilerin üçerli hareketli ortalamaları Fourier analizi ile değerlendirildi. KOAH yatışlarının Eylül ayında artmaya başladığı, Ocak ayında maksimum seviyeye ulaştığı ve Mart ayından sonra azalarak yaz ayları boyunca düşük bir seviyede devam ettiği saptandı (F=7.679, p

Aims: To determine the seasonal variation in patterns of hospitalizations for COPD Methods: We studied the data of 3089 hospitalizations extracted from 3617 hospitalizations in the chest clinic between 1987-1998. Results: Amongst these, 397 (12.9%) cases have been classified as COPD (chronic bronchitis, emphysema, ICD9: 490-492 and COPD not specified elsewhere, ICD9: 496). Monthly hospitalization number for COPD were standardized to monthly hospitalizations to the chest clinic and three by three moving averages of these standardized data were analyzed with Fourier's analysis. Hospitalizations for COPD were starting to increase by October and reaching to maximum level at January, decreasing by- March and stable for the spring and summer (F=7.679, p<0.001). Through this 12 year-period, annual hospitalization for COPD increased from 28 to 68 but COPD ratio to all patients decreased from 20.3% to 10.9%. Additionally, average stay in hospital decreased from 14.4±14.1 days in the 1987-1990 to 9.8±7.3 days in the 1995-1998 (P<0.01). Conclusion: Decrease in hospitalization ratios and staying times in spite of increasing number of the COPD patients may be attributed development in the diagnosis and treatment, and increasing preventive measures such as vaccination. Seasonal patterns in hospital morbidity may identify triggers provoking COPD exacerbations and may help in planning of health care services.