In our national study of peer review practices, case volume was a factor contributing to a program’s perceived quality impact. (1) A benefit was apparent above 1% of hospital inpatient volume. While there was extreme variation in rates of cases screened out of the peer review process, those rates bore no relationship to the volume of cases proceeding to formal peer review or to the perceived quality impact of the program.
The importance of case volume may seem surprising in relation to QI principles. Ordinarily, we want to minimize the cost of inspection by designing quality into the process.
The explanation may be that clinical care is largely a poorly controlled process. The Harvard Medical Practice Study (HMPS) and similar investigations have shown that adverse event rates typically exceed 3%, with physician management issues contributing to about a third of these. (2) Thus, programs with review volume lower than 1% could not identify most individual improvement opportunities.
This problem is exacerbated by the low specificity of the commonly used generic screens. In the HMPS, almost 26% of randomly selected records screened positive for possible adverse events by nurse reviewers using 18 generic screens. Of those cases going on to physician review, 16.5% were determined to have an adverse event and 4% had compelling evidence of substandard care. Other authors have looked at this problem, but none have found a practical solution. (3, 4)
Even worse, they would be passing over many potential opportunities for improvement in the system of care.
Graber showed that such system of care opportunities can be readily identified through the peer review process. (5) His group found 4 times as many system issues as provider negligence. Using fairly conventional methods for case identification, they only found negligence in 11% of cases reviewed. Their annual case volume was 2% of service volume.