To assess the impact of facility case mix on cross‐sectional variations and short‐term stability of the “Nursing Home Compare” incontinence quality measure (QM) and to determine whether multivariate risk adjustment can minimize such impacts.
Retrospective analyses of the 2005 national minimum data set (MDS) that included approximately 600,000 long‐term care residents in over 10,000 facilities in each quarterly sample. Mixed logistic regression was used to construct the risk‐adjusted QM (nonshrinkage estimator). Facility‐level ordinary least‐squares models and adjusted were used to estimate the impact of case mix on cross‐sectional and short‐term longitudinal variations of currently published and risk‐adjusted QMs.
At least 50 percent of the cross‐sectional variation and 25 percent of the short‐term longitudinal variation of the published QM are explained by facility case mix. In contrast, the cross‐sectional and short‐term longitudinal variations of the risk‐adjusted QM are much less susceptible to case‐mix variations (adjusted <0.10), even for facilities with more extreme or more unstable outcome.
Current “Nursing Home Compare” incontinence QM reflects considerable case‐mix variations across facilities and over time, and therefore it may be biased. This issue can be largely addressed by multivariate risk adjustment using risk factors available in the MDS.