title: Duke Case-Mix System (DUMIX) for ambulatory health care.
abstract: The Duke Case-Mix System (DUMIX), which combines age, gender, patient-reported perceived and physical health status, and provider-reported or auditor-reported severity of illness to classify patients by their risk of high future utilization, explained 17.1% of the variance in future clinic charges and 16.6% of the variance in return visits. When a random half of 413 ambulatory adults were classified into four risk classes by predictive regression coefficients from the other half, there was a stepwise increase in actual future utilization by risk class. The most accurate classification was for Class 4 (highest risk) patients, with a sensitivity of 40.8%, specificity of 82.1%, and likelihood ratio of 2.3. These 23.7% of patients accounted for 44.2% of charges for all patients. When predictive coefficients from this population were used to classify a different group of 206 ambulatory adults, past utilization also increased in stepwise order by case-mix class.
authors.affiliation: Department of Community and Family Medicine, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: G R
authors.initials: GR
authors.lastname: Parkerson
authors.forename: J L
authors.initials: JL
authors.lastname: Michener
authors.forename: K S
authors.initials: KS
authors.lastname: Yarnall
authors.forename: W E
authors.initials: WE
authors.lastname: Hammond
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000553:Ambulatory Care / Q000145:classification* / Q000592:standards; D003363:Cost Control; D003953:Diagnosis-Related Groups / Q000145:classification* / Q000592:standards; D005260:Female; D005500:Follow-Up Studies; D006305:Health Status Indicators; D006801:Humans; D008297:Male; D008329:Managed Care Programs; D008875:Middle Aged; D011237:Predictive Value of Tests; D011897:Random Allocation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires