reports

Measuring morbidity in populations: performance of the Johns Hopkins Adjusted Clinical Group (ACG) case-mix adjustment system in Manitoba

Winnipeg, MB, Canada: Manitoba Centre for Health Policy.

Manitoba Centre for Health Policy, Winnipeg, MB, Canada

This study examined the performance of the Johns Hopkins Adjusted Clinical Group (ACG) system in measuring the morbidity of individuals and populations in the province of Manitoba. The ACG system, which was developed by researchers at the Johns Hopkins University, estimates the illness burden of individual patients and, when aggregated across individuals, of populations. ACGs represent a new class of case-mix tools which measure individuals’ overall morbidity across their range of illness episodes experienced over the course of a year. This longitudinal perspective on morbidity has found a diverse array of research and management applications in the United States, including adjusting provider payment rates and profiling practices. Although the system has been extensively validated in the United States and more recently Europe, experience with the system in Canada has been limited. Given the potentially broad applicability of this tool in Canada for both research and administrative purposes, this study aimed to assess ACG performance using existing administrative data from the province of Manitoba. The specific aims of the study were to:(1) assess the performance of the ACG system in explaining variation in the health care provided to individual Manitobans; and (2) evaluate the extent to which the ACG system can provide a valid measure of population health ‘need’ through comparison with other generally accepted measures of population health. The study was based on demographic, diagnostic, and expenditure data from Manitoba Health’s patient registration, physician claims, and hospital separation files for fiscal year 1995/96.