Validity and responsiveness of the minimum data set

OBJECTIVE: To determine the criterion validity and responsiveness to change over time of the Minimum Data Set (MDS). DESIGN: Cross sectional analysis comparing prospectively collected research data with MDS data reported from nursing homes on identical subjects. Long itudinal follow-up of subjects allowed for calculation of responsiveness to change over time. PARTICIPANTS: Subjects (n = 140) participating in epidemiological research on the natural history of Alzheimer's disease in the University of Washingt on Group Health Cooperative Alzheimer's Disease Patient Registry (ADPR) who entered nursing homes in Washington State from January 1990 through March 1996. MAIN OUTCOME MEASUREMENTS: Spearman's correlation coefficients to compare M DS cognitive performance scale scores with Mini-Mental State Examinations ( MMSE), MDS behavior domain scores with ADPR Physician Behavior checklist sc ores, and MDS activities of daily living (ADL) functioning scores with Deme ntia Rating Scale scores for ADLs. Partial correlations were used to contro l for the number of days between MDS and ADPR assessments, age, and functio n in the other two MDS ratings of ADL, cognition, or behavior. We determine d responsiveness by using the mean change in an effect size (ES) calculatio n for each domain of interest. RESULTS: MDS measures in all three domains were correlated modestly to the analogous ADPR research instruments, with correlation coefficients 0.45 for cognition, 0.50 for behavior, and 0.59 for ADL functioning. Controlling fo r age, time between ADPR and MDS assessments, and the MDS ratings of the ot her two MDS domains did not improve the correlations significantly. In a su bgroup of 60 subjects followed for an average of 636 days, the Cognitive pe rformance scale of the MDS had a slightly larger effect size (ES = 0.60) th an the Folstein Mini-Mental Status Exam (ES = 0.39) used by the ADPR. Howev er, the Dementia Rating Scale (ES = 0.77) used by the ADPR researchers refl ected more change over time than the ADL domain of the MDS (ES = 0.02). The MDS behavior domain (ES = 0.058) was comparable to the research behavior c hecklist (ES = 0.065). CONCLUSIONS: These data demonstrate reasonable criterion validity of the MD S and the MMSE, ADL, and behavior rating scales and suggest that the MDS da ta is of adequate validity for research purposes in these areas. The MDS wa s less able to capture dementia-related change in ADLs in this population o f patients with dementia even though the same nursing home staff completing the MDS often supplied the information for completing the research scales. As a result, the MDS may be limited as an outcome assessment instrument.