In their paper on the effect of illness adjustment on regional mortality and spending rates using standard and visit corrected illness methods for adjustment, Wennberg and colleagues compare adjustment using diagnoses listed in administrative databases with additional adjustment for the frequency of doctors’ visits.1 They acknowledge that data on the use of healthcare cannot be used directly as a proxy for need or risk because these data also reflect differences in access to and supply of healthcare services. However, the methods of risk adjustment developed by these and other authors are based exactly on these data. Steventon’s editorial does not challenge this approach.2 Myself and Michael Soljak suggest in a letter published in the BMJ that this problem should be approached using the fundamental public health principle of disease prevalence in a population (“health needs assessment”). Good measures of the incidence and prevalence of disease known to primary healthcare services a...
Updates from Imperial College London's Professor of Primary Care & Public Health