Health Surveillance for Asthma in the US Navy: Experience of 9,185,484 Person-years

Purpose To measure trends and demographic risk factors for hospitalization for asthma. Methods Time trends and demographic risk factors, for hospitalized asthma (1CD-9-CM Code 493) were analyzed by measuring age-specific and age-adjusted first hospitalization rates in a defined population of active-duty enlisted members of the US Navy worldwide during 1980–1999, consisting of 9,185,484 person-years. Results There were 3911 patients first hospitalized for asthma, including 2916 men and 995 women. The age-adjusted incidence rate of first hospitalization for asthma was three times higher in women than men, 110 per 100,000 person-years (95% confidence interval [CI], 104–117), compared with 35 per 100,000 person-years (95% CI, 33–37), respectively (p < 0.0001). The rate in black women was twice as high as in white women, 186 per 100,000 person-years, compared with 99 per 100,000 person-years, respectively (p < 0.001). The rate in black men was higher than in white men, 45 per 100,000, compared with 34 per 100,000 (p < 0.001). Age-adjusted rates in women doubled from 73 per 100,000 in 1980–1983 to 159 in 1997–1999 (p for trend < 0.01), while those in men remained stable. Conclusions Age-adjusted incidence rates of first hospitalization for asthma were three times as high in women as in men, and doubled during the period between 1980 and 1999. The rates in black women were twice as high as in white women. The reasons are unknown.