Postoperative venous thromboembolism rates may not be an effective way of measuring hospital quality, according to Dr. Karl Y. Bilimoria and his colleagues.
The investigators calculated patient-level rates of venous thromboembolism as well as rates of imaging for VTE using data from the American Hospital Association and Medicare Compare from 2009-2010 from nearly 1 million patients discharged from 2,786 hospitals after a major surgery.
They sought to determine the association between hospital adherence to VTE reduction protocols (Surgical Care Improvement Project for VTE or SCIP-VTE-2) and risk-adjusted rates of VTE as measured by Patient Safety Indicator 12 (PSI-12) from the Agency for Healthcare Research and Quality. They also looked at how overall hospital quality scores correlated with VTE prophylaxis and risk-adjusted VTE scores.
Dr. Karl Bilimoria
Their findings were presented at the annual clinical congress of the American College of Surgeons and simultaneously published Oct. 7 in JAMA (2013 Oct. 7 [doi:10.1001/jama.2013.280048]).
Hospitals that adhered consistently to VTE reduction protocols paradoxically had higher PSI-12 scores, although not significantly so (P = .03). Hospitals with higher overall quality scores also adhered to VTE reduction protocols at a higher rate (93.3% in the lowest quartile vs. 95.5% in the highest) and had significantly higher risk-adjusted VTE event scores (P less than .001).
"Most important, hospital VTE rates were associated with the intensity of detecting VTE with imaging studies," the investigators said. Mean VTE diagnostic imaging rates ranged from 32/1,000 in the lowest quartile to 167/1,000 in the highest.
Hospitals with the lowest imaging rates diagnosed 5.0 VTEs per 1,000 discharges, compared with hospitals with the highest imaging rates diagnosing 13.5 VTEs per 1,000 discharges.
In effect, PSI-12 scores the use of VTE imaging by hospitals instead of the quality of care provided, the investigators said. Further, surveillance bias impedes quality performance improvements; thus, decision making becomes more difficult for "patients seeking to identify a high-quality hospital."
In an accompanying editorial, Dr. Edwin H. Livingston, deputy editor of JAMA, noted that hypervigilance of VTEs might further worsen care in that "the very high compliance rate with VTE prophylaxis might result from many patients receiving treatments from which they are not likely to benefit. This is because current process measures were based on older guidelines that overestimated the benefits of VTE prophylaxis" (JAMA 2013 Oct. 7 [doi:10.1001/jama.2013.280049]).
For that reason, Dr. Livingston recommended that public reporting of VTEs be "reconsidered or curtailed because few hospitals have sufficient numbers of patients to show statistically significant effects of prophylactic measures on VTE rates."
The study was funded by the AHRQ and Northwestern University. Dr. Bilimoria has received honoraria from hospitals, professional societies, and continuing medical education companies for presentation on quality improvement.