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

Abstract

Objective: 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.

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

Data collection/extraction methods: 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.

Principal findings: 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.

Conclusions: 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.

Figure 1

Annual Smoothed Rates (and Standard Errors), for the Four Most Frequent Patient Safety Indicators (PSIs) in the Veterans Health Administration Health Care System, Which Are the Only PSIs to Yield Significant Time Trends at the National Level. Note: Left y-axis is smoothed rate for Failure to Rescue; right y-axis is for Decubitus Ulcer, Post-Op DVT, and Accidental Puncture.

Figure 2

IntraClass Correlations of Smoothed Patient Safety Indicator (PSI) Rates, for VISNs across 9 Years, 1997–2005, Plotted against Average Annual Number (throughout the VA) of PSI Adverse Events (Rate Explains >50 percent of Variance in Other Years' Rates for PSIs 4, 11, and 12 Only).

Figure 3

Average Percentages of VISNs, or Hospitals, That Were, among the Lowest, Middle, or Highest Third of Smoothed Patient Safety Indicator (PSI) Rates in 2001, and Also Were in the Same Third in Other Years. Percentages in the Same Third in Each of the Other 8 Years Were Averaged. PSIs Are Listed in Order of Frequency.