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Reliability of hospital readmission rates in vascular surgery
Andrew A Gonzalez1, Micah E Girotti2, Terry Shih2
1Department of Surgery, Center for Healthcare Outcomes and Policy (CHOP), University of Michigan, Ann Arbor, Mich; Department of Surgery, University of Illinois Hospital and Health Sciences System, Chicago, Ill.
Insights
Hospital readmission rates for vascular surgery fluctuate significantly year-to-year. This suggests that readmissions may not reliably indicate consistent hospital quality, as much variation is random or due to unmeasured factors.
Area of Science:
- Health Services Research
- Vascular Surgery Outcomes
- Healthcare Quality Measurement
Background:
- The Centers for Medicare and Medicaid Services (CMS) penalize hospitals for high readmission rates.
- These penalties are expanding to surgical conditions, including vascular surgery.
- Reliability of readmissions as a hospital performance metric in vascular surgery is under scrutiny.
Purpose of the Study:
- To assess if hospital readmission rates are a reliable predictor of performance in vascular surgery.
- To evaluate the year-to-year reliability of risk-adjusted readmission rates in vascular procedures.
Main Methods:
- Analysis of 4 years of national Medicare claims data for 1576 hospitals.
- Inclusion of 81,520 abdominal aortic aneurysm repairs and 57,190 lower extremity arterial bypasses.
- Utilized test-retest reliability methods, including Spearman rank correlation and weighted kappa, comparing 2005-2006 and 2007-2008 readmission rates.
Main Results:
- A moderate correlation (Spearman r = 0.57, weighted κ = 0.42) was found between readmission rankings in the two periods.
- Only 32% of the variation in 2007-2008 readmission rates was explained by prior years' data.
- Significant hospital reclassification occurred, with 63% of hospitals changing performance quintiles between periods.
Conclusions:
- Risk-adjusted readmission rates in vascular surgery exhibit substantial year-to-year variability.
- This variability implies that a significant portion is attributable to random chance or unmeasured factors, not solely changes in hospital quality.
- Readmissions may not be a consistently reliable administrative data measure of hospital performance in vascular surgery.
Objective:
The Center for Medicare and Medicaid Services recently began assessing financial penalties to hospitals with high readmission rates for a narrow set of medical conditions. Because these penalties will be extended to surgical conditions in the near future, we sought to determine whether readmissions are a reliable predictor of hospital performance with vascular surgery.
Methods:
We examined 4 years of national Medicare claims data from 1576 hospitals on beneficiaries undergoing three common vascular procedures: open or endovascular abdominal aortic aneurysm repair (n = 81,520) or lower extremity arterial bypass (n = 57,190). First, we divided our population into two groups on the basis of operative date (2005-2006 and 2007-2008) and generated hospital risk- and reliability-adjusted readmission rates for each time period. We evaluated reliability through the use of the "test-retest" method; highly reliable measures will show little variation in rates over time. Specifically, we evaluated the year-to-year reliability of readmissions by calculating Spearman rank correlation and weighted κ tests for readmission rates between the two time periods.
Results:
The Spearman coefficient between 2005-2006 readmissions rankings and 2007-2008 readmissions rankings was 0.57 (P < .001) and weighted κ was 0.42 (P < .001), indicating a moderate correlation. However, only 32% of the variation in hospital readmission rates in 2007-2008 was explained by readmissions during the 2 prior years. There were major reclassifications of hospital rankings between years, with 63% of hospitals migrating among performance quintiles between 2005-2006 and 2007-2008.
Conclusions:
Risk-adjusted readmission rates for vascular surgery vary substantially year to year; this implies that much of the observed variation in readmission rates is either random or caused by unmeasured factors and not caused by changes in hospital quality that may be captured by administrative data.
