Market Factors May Influence Coronary Artery Bypass Graft Timing

Use of early coronary artery bypass grafting after acute myocardial infarction is influenced by state, hospital and payer characteristics, however, timing of the procedure does not appear to affect mortality, researchers report.

Investigators carried out an analysis of data from the Healthcare Cost and Utilization Project at the Agency for Healthcare Research and Quality (AHRQ) that included all coronary artery bypass grafting (CABG) performed in short-stay, non-federal hospitals in California, Massachusetts, New Jersey and Wisconsin from 1989 to 1996.

CABGs were considered early if acute myocardial infarction was the principal diagnosis. The investigators broke early CABGs down into those performed on days three to eight and those on day nine and after.

There were 367,387 CABGs performed in the four states during the eight-year time period. Frequency of early CABG increased from 1989 (five to 12 percent) to 1996 (17 to 21 percent). Mortality for early CABG patients and other CABG patients were similar (3.37 percent versus 3.31 percent).

Multivariate analysis showed that in-hospital mortality was not affected by timing of CABG, state or payer. Mortality was, however, twice as likely for patients with age over 71 years, co-morbidity or complications.

Early CABG was 50 to 60 percent less likely in California, New Jersey and Wisconsin as compared with Massachusetts. It was also 15 to 50 percent less likely with co-morbidity or severity.

Early CABG was 15 percent more likely in high volume hospitals and 16 percent more likely with private insurance compared with Health Maintenance Organizations. It was also twice as likely following angioplasty.

“These findings provide evidence that market factors play a significant role in the timing of CABG following acute myocardial infarction,” the authors suggest. “Future studies will examine which market factors, including physicians, payer and hospital competition, are most important.”