Socioeconomic variation in asthma hospitalization: Excess utilization or greater need?

Objective. To assess the hypothesis that higher incidence of severe acute a sthma exacerbation, not lower severity threshold for admission, explains th e difference between the asthma hospitalization rates of inner-city and sub urban children. Methods. All 2028 asthma hospitalizations between 1991 and 1995 for childre n (aged >1 month and <19 years) dwelling in Rochester, New York, were analy zed. ZIP codes defined residences as inner-city, other urban, or suburban. Based principally on the worst oxygen saturation (Sao(2)) during the first 24 hours of hospitalization, severity was examined by hospital record revie w (n = 443) of random samples of inner-city, other urban, and suburban asth ma admissions. Results. Large inner-city/suburban differences were noted in many sociodemo graphic attributes, and there was also a distinct, stepwise gradient in ris k factors in moving from the suburbs to other urban areas and to the inner city. Racial and economic segregation was particularly striking. Black indi viduals accounted for 62% of inner-city births versus <3% in the suburbs. M edicaid covered 65% of inner-city births, whereas Medicaid covered only 6% of suburban births. The overall asthma hospitalization rate was 2.04 admissions/1000 child-year s. Children <24 months old, those most commonly hospitalized for asthma, we re fourfold more likely to be hospitalized (OR: 3.97, 95% CI: 3.44-4.57) th an children between the ages of 13 and 18 years. The hospitalization rate o f asthma in boys was almost twice the rate of asthma in girls. The greatest gender difference was observed among children who were <24 months old. For these children, the rate for boys was 6.10/1000 child-years compared with 2.65/1000 child-years for girls (OR: 2.31, 95% CI: 1.95-3.03). This gender difference diminished gradually in older age groups to the extent that ther e was no difference among girls and boys between the ages of 13 and 18 year s (males, 1.12/1000 child-years vs females, 1.09/1000 child-years). Based on worst Sao(2) values, mild (worst Sao(2) greater than or equal to 9 5%), moderate (90%-94%), and severe (<90%) admissions constituted 10.3%, 41 .9%, and 47.7% of all hospitalizations, respectively. Although rates within the community followed a distinct geographic pattern of suburban (1.05/100 0 child-years) < other urban (2.99/1000 child-years) < inner-city (5.21/100 0 child-years), the proportions of admissions with low severity did not var y among areas. Likewise, the proportions of admissions that were severe (Sa o(2) <90%) were not significantly different (44.8, 45.7, and 52.1% for subu rban, other urban, and inner-city areas, respectively). The distributions o f asthma severity, measured by the duration of frequent nebulized bronchodi lator treatments and the length of hospital stay, were also similar among c hildren from different socioeconomic areas. Conclusion. The marked socioeconomic and racial disparity in Rochester's as thma hospitalization rates is largely attributable to higher incidence of s evere acute asthma exacerbations among inner-city children; it signals grea ter need, not excess utilization. Both adverse environmental conditions and lower quality primary care might explain the higher incidence. Interventio ns directed at the environment offer the possibility of primary prevention, whereas primary care directed at asthma is focused on secondary prevention , principally on improved medication use. Higher hospitalization rates cannot be assumed to identify opportunities fo r cost reduction. The extent to which our observations about asthma hold tr ue under other conditions and in other communities warrants systematic atte ntion. Knowledge of when higher rates signal excess utilization and when, i nstead, they signify greater needs should guide equitable national health p olicy.