Stability of nursing home quality indicators over time

BACKGROUND. Nursing home quality indicators (QIs) provide a way to support quality assurance and improvement activities and to help ensure that cost s avings are based on increased efficiency and not on decreased quality of ca re. OBJECTIVES. QIs values are expected to change over time. However, to be goo d indicators of quality, they should be reasonably stable over "short" peri ods. This paper discusses theoretical and measurement issues affecting stab ility and examines the stability of QIs over each of two 3-month periods an d one 6-month period. SUBJECTS. The study sample included 512 nursing facilities from two states, Kansas and South Dakota. QIs were measured for the first 3 quarters of 199 6. MEASURES. Facility level QIs were constructed using three different metrics that each provide a unique perspective of facility performance as follows: the proportion of residents in the facility with the QI condition; the fac ility's percentile rank in its state; and a variable indicating whether the facility's rank exceeded the 90th percentile in its state. QI stability wa s assessed using Pearson correlation coefficients, Spearman rank order corr elation coefficients, and Cohen's Kappa, as appropriate for the metric. RESULTS. Results indicated high levels of stability for most QIs, with lowe r levels of stability found to be in keeping with theoretical and measureme nt considerations. CONCLUSIONS. QIs are reasonably stable over short periods of time. Quality improvement efforts may best be focused on facilities that are consistently poor performers over time, and those that show a large decrease in quality from one quarter to the next.