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Physician Experience vs. Hospital Volume in Primary PCI
Abstract & commentary
By Jonathan Abrams, MD, Professor of Medicine, Division of Cardiology, University of New Mexico, Albuquerque Dr. Abrams serves on the speaker's bureau for Merck, Pfizer, and Parke-Davis.
Source: Srinivas VS, et al. Effect of physician volume on the relationship between hospital volume and mortality during primary angioplasty. J Am Coll Cardiol. 2009;53:574-579.
Efforts to decrease door-to-balloon time for primary percutaneous intervention (PCI) in an acute ST elevation myocardial infarction (STEMI), may include preferential triage to hospitals expert in primary PCI, partly because of evidence suggesting better outcomes. Others suggest increasing the number of hospitals capable of performing primary PCI, as more experienced cardiologists are available in community hospitals with high efficacy in primary PCI. This study assesses the interaction between hospital and physician volume for primary PCI in STEMI using the New York State PCI reporting system.
The database consists of all acute STEMI PCI patients in New York over a two-year period (January 2000 to December 2002). PCI was carried out within 12 hours of chest pain, without thrombolytic therapy, by 266 physicians in 7,321 patients with STEMI. The yearly volume of PCI was obtained for each hospital and cardiologist. The major outcome was in-hospital mortality. Hospitals were categorized as < 50 or > 50 cases/year. Physician PCI volumes were categorized by < 10, 10-20, and > 20 cases/yr. Risk-adjusted mortality was calculated and predicted for each patient as the ratio of observed mortality to predicted mortality multiplied by the statewide mortality rate of 3.7%. The independent effect of hospital and physician volume on mortality was tested.
Results: Mortality was lowest in high-volume hospitals and with high-volume physicians (OR .58 and .66, respectively). However, risk-adjusted mortality rates were not statistically different between high-volume physicians in high-volume hospitals vs. low-volume physicians in low-volume hospitals (3.8% vs. 8.4%, p = 0.09). Also, high-volume physicians in low-volume hospitals had a risk-adjusted mortality of 4.8% vs. low-volume physicians of 8.4%. Whereas, in a high-volume hospital, low-volume physicians' mortality rate was 6.5% vs. 3.8% for high-volume physicians. Srinivas et al concluded that physician experience significantly affects the hospital-volume mortality relationship.
This report validates the power of PCI procedure volume in determining PCI results in patients with acute STEMI taken to the cath lab for immediate PCI. The data are unique in that all cath labs in New York are obligated to supply information about their PCI results. While hospital procedure volume is important, hospital volume does not show a strict correlation with hospital mortality. For instance, in hospitals with > 75 per year volume, risk-adjusted hospital rate was 3.32%, compared to 4.24% in hospitals < 75 per year, p = NS. Also, they demonstrate a dynamic relationship among hospital volume, physician volume, and mortality rates, which suggests that operator experience is a major factor in determining outcomes of primary PCI.
The main problem with these interesting data regarding high-volume and low-volume physicians and hospitals is the time elapsed between the present and 2000-2002; the data, thus, reflect PCI practice of up to nine years ago. This observation is not mentioned by Srinivas et al; more up-to-date data are likely to be at least equivalent or more likely superior, given the enormous interest in activating STEMI hospitals en route, sending ECG data en route or "straight to lab," activation done by ER and/or cardiology personnel. Moving the patient from the ambulance directly to the ER (better yet, directly to the cath lab), and emphasizing door-to-balloon time rather than the gross club of hospital volume, are important advances. It is likely that current practices and equipment are important, but physician expertise remains the mainstay of PCI in STEMI and all other invasive procedures.