Area variation in mortality from diseases amenable to medical intervention: the contribution of differences in morbidity.

Several conditions, whose timely and appropriate therapy should decrease case fatality, have been proposed as indicators of medical care quality for the National Health Service. Mortality rates for these diseases vary widely within the UK. To evaluate the contribution of varying incidence rates to these mortality differences, routinely collected morbidity and mortality data for 1974-1978 were analysed for 98 Area Health Authorities (AHAs) in England and Wales. Although differences in morbidity (as measured by hospital discharge and disease registration rates) and socioeconomic factors account for some of the area variation in mortality, significant heterogeneity persists after these factors are taken into account. This finding suggests that morbidity and socioeconomic factors are not the only determinants of mortality variation among areas for these particular diseases. Variation in quality of medical care may account for this result, although regional diagnostic and reporting differences and variation in disease severity among areas must also be considered.