Does quantity mean quality? - An analysis of 116,000 patients regarding the connection between number of cases and quality of the results

Methods: Between 1993 and 1998 data of 27,000 patients with hip fractures a nd 89,000 patients undergoing cholecystectomy were collected by the departm ent of external quality assurance at the chamber of physicians of Westphali a-Lippe. The data were analyzed for the relationship between volume and out come, specified as mortality and morbidity. Logistic regression was used to adjust the results for demographic and clinical risk factors. Results: The risk-adjusted probability of death from cholecystectomy was 89% higher in the group of small volume clinics (less than 30 procedures per year) than i n the group of large volume clinics (more than 120 procedures per year) (od ds ratio 1.89; 95% CI 1.19-3.00). Mortality from hip fractures was 33% high er (odds ratio 1.33, 95% CI 1.09-1.63) for the group of small volume clinic s (less than 15 procedures per year) than the group of large volume clinics (more than 45 procedures per year). Among the group of small volume hospit als were some with excellent results, but they are more likely to be found in the group of large volume hospitals. On the other hand there were some d epartments with poorer results in the group of large hospitals. Conclusions : There is no threshold for good results. In general there is an inverse re lationship between volume and outcome. High volume, though, is not a substi tute for good results. It is not possible to infer good quality from high v olume alone. Small-volume departments should document quality of care and r esults thoroughly.