Rare adverse medical events in VA inpatient care: reliability limits to using patient safety indicators as...

To assess Agency for Healthcare Research and Quality's Patient Safety Indicators (PSIs) as performance measures using Veterans Administration hospitalization data. DATA SOURCES STUDY SETTING: Nine years (1997-2005) of all Veterans Health Administration (VA) administrative hospital discharge data.

Retrospective analysis using diagnoses and procedures to derive annual rates and standard errors for 13 PSIs.

For either hospitals or hospital networks (Veterans Integrated Service Networks [VISNs]), we calculated the percentages whose PSI rates were consistently high or low across years, as well as 1-year lagged correlations, for each PSI. We related our findings to the average annual number of adverse events that each PSI represents. We also assessed time trends for the entire VA, by VISN, and by hospital.

PSI rates are more stable for VISNs than for individual hospitals, but only for those PSIs that reflect the most frequent adverse events. Only the most frequent PSIs yield significant time trends, and only for larger systems.

Because they are so rare, PSIs are not reliable performance measures to compare individual hospitals. The most frequent PSIs are more stable when applied to hospital networks, but needing large patient samples nullifies their potential value to managers seeking to improve quality locally or to patients seeking optimal care.