Geographic variations in US asthma mortality: small-area analyses of excess mortality, 1981-1985.

US asthma mortality rates have been increasing during the past 10 years. Little is known about the geographic variation of this infrequent health event. Using US vital records for the 1981-1985 period, small-area variation of excess asthma mortality of young adults was studied. Several geopolitical definitions were used to define populations. A total of 22 single counties, 12 metropolitan statistical areas, 11 health service areas, and 29 state economic areas were identified as having mortality significantly in excess of that expected, based on US race/sex-specific rates. Significant variation in asthma mortality was found at several levels of geopolitical classification of the data. Elevated areas included the central plains states and three large urban metropolitan areas--Chicago, Illinois, New York, New York, and Phoenix, Arizona--as well as a few mostly suburban populations. Areas with excess mortality may provide a useful population base for further epidemiologic investigation into the risk factors associated with the more frequent morbid events of this disease, such as emergency room and hospital utilization.