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Many studies have shown that "practice makes perfect" when it comes to medical procedures—that is, hospitals or physicians who perform a higher volume of a given procedure usually have better outcomes than those who perform few such procedures. In this study, the researchers examined the association between hospital and physician volume and the use of aspirin and reperfusion therapy in eligible patients in the first 24 hours after acute myocardial infarction (AMI, heart attack).
They reviewed charts of 2,215 patients treated at 35 Minnesota hospitals for AMI between October 1992 and July 1993. They found that the lowest volume hospitals (treating less than 30 AMI patients over 10 months) had a 50 percent reduction in the odds of using aspirin compared with the highest volume hospitals (treating more than 200 patients). Unexpectedly, the study also found that the low-volume hospitals—many of which were in rural areas—were about 20 percent more likely to use thrombolytics for AMI patients.
The researchers attribute this to the clinicians' lack of access to alternatives, such as cardiac catheterization labs and cardiologists. They simply had no alternative, and the use of thrombolytics may have been a "desperation reaction," suggests Donald Willison, Sc.D., lead author of the study at Harvard Medical School. This research was supported in part by the Agency for Healthcare Research and Quality (HS07357).
Dr. Stephen Soumerai, principal investigator of the AHRQ study, and his colleagues reviewed the medical charts of 2,215 patients treated at 35 Minnesota hospitals for AMI in 1992 and 1993. They compared the use of aspirin and thrombolytic therapy in eligible patients across different physician and hospital volume categories. They found that hospital volume and physician volume of patients treated were only weakly associated with use of aspirin and reperfusion therapy. Differences appeared chiefly in the lowest volume hospitals.
Because heart attack is an emergency condition, timing is very important for saving lives, and selective referral of patients to higher volume hospitals or physicians generally is not an option. Almost half of the hospitals participating in this study were in rural locations and treated less than three AMI patients per month. Also, 35 percent of the physicians who were identified as primary prescribers treated five patients or less in the entire 10-month study period. At such low volume, it is difficult to maintain expertise. The widespread use of protocols and rural outreach projects conducted by urban cardiologists at the time may well have compensated for the lack of individual physician or hospital experience in treating AMI patients, concludes Dr. Willison.
For more details, see "Association of physician and hospital volume with use of aspirin and reperfusion therapy in acute myocardial infarction," by Drs. Willison and Soumerai and R. Heather Palmer, M.B., B.Ch., S.M., in the November 2000 Medical Care 38(11), pp. 1092-1102.
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