Excerpt

Hirsch and colleagues [5] report a complex analysis aimed at defining the relationship between institutional volume and hospital mortality for congenital heart surgery and, not surprisingly, suggest that high-volume institutions have lower hospital mortality than low-volume institutions. Although the presented data are restricted to two specific procedures, the conclusions are consistent with the majority of reports examining this issue using a wider range of procedures [4, 6]. However, it should be noted that others have not always found a consistent relationship between hospital volume and outcome [7]. Therefore, it is important to recognize the possibility that hospital volume may be a proxy for other aspects of care that are important predictors of survival and may be more commonly associated with high-volume centers [2]. This concern is supported by the observation that in most published analyses there are some low-volume centers that have risk-adjusted mortality which is equivalent (or superior) to that of large-volume centers [2, 6]. Comparison of diagnosis-specific cohorts within the Congenital Heart Surgeons Society using databases that are rich in patient-specific and institution-specific data suggests that there is considerable heterogeneity in the relationship between institutional (and surgeon) performance and volume. Some lesions appear to have outcomes that are related to volume, whereas patient and institutional management patterns may be the primary determinants of outcome with other lesions. Also, and importantly, an institution with superb performance with one lesion may have quite mediocre performance with another lesion. …