Editorial: Is volume a proxy for quality?
Tiit Illimar Mathiesen · Journal of neurosurgery · 2015
When we go to a restaurant, we make our choice depending on what kind of experience and what kind of quality we are looking for.We can usually get better wines and ingredients, and cooking with higher skill and attention to detail, if we are prepared to pay more.We usually do not select the restaurant that has the largest volume for the highest quality, although a certain volume may allow cost-effective meals; for example, hamburgers to feed the hungry are not costly in large-volume enterprises.But somehow we have come to believe that volume equals quality in medicine.A number of epidemiological studies of US hospitals have shown lower mortality and morbidity in high-volume medical centers.Subsequently, hospital volume has become associated with better outcomes and is frequently thought of as an independent predictor of quality of care.Dr. Lindekleiv et al. have analyzed 1-year mortality after treatment of intracranial aneurysms in Scandinavian centers to corroborate the correlation of hospital volume and outcome. 1 These investigators did not find this correlation: there were large differences in mortality after treatment across hospitals and between countries, and the findings did not consistently show lower long-term mortality rates in higher-volume centers.The findings are seemingly shocking and surprising.Scandinavia is a small region with a homogenous culture and health care system, and large differences would primarily not have been expected.Yet, we have previously detected large differences in survival after glioma treatment within Sweden, in spite of a legal requirement of equal health care for all. 2 Likewise, Lindekleiv et al. found large differences in survival after treatment of aneurysms in Scandinavia.It is not possible to know whether the differences reflect a different quality of treatment or were influenced by selection of patients.There could be a selection bias from different policies of treating patients with high Hunt and Hess grades.Lindekleiv et al. have not assessed mortality rates for untreated patients and have not assessed patients who were not transferred to neurosurgical departments.The study of Lindekleiv et al. is, however,