Specialization Improves Neurosurgery Outcomes Regardless of Case Volume
Key findings
- Increased specialization in spinal or cranial surgery was significantly associated with reductions in the predicted probability of death and adverse discharge disposition
- Total volume of cases was also significantly associated with reductions in poor outcomes
- Rather than trying to increase the quantity of procedures one performs, it may be more feasible to establish a division of labor with partners such that each surgeon maintains a more specialized practice
Subspecialization is an ongoing trend in neurosurgery, but it has been unclear whether the degree of surgeon specialization is associated with improved patient outcomes. Bob S. Carter, MD, PhD, chief of Neurosurgery at Massachusetts General Hospital, and colleagues have determined that specialization in spinal or cranial surgery is significantly and independently linked to improved mortality and morbidity, even after controlling for case volume.
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Published in the Journal of Neurosurgery, Dr. Carter and his co-authors report on their analysis of 12 years of data (1998-2009) from the Nationwide Inpatient Sample. That database captures 100% of discharges from a 20% stratified sample of U.S. hospitals. The researchers identified 231,875 patients who underwent instrumented surgery of either the lumbar or cervical spine and 46,029 patients who underwent lobectomy or parenchymal excision of a mass lesion.
The unit of analysis for the research was the neurosurgeon-year, defined as the set of all patients who underwent operations by a neurosurgeon during a calendar year. There were 4,656 neurosurgeon-years in the spinal cohort and 4,304 neurosurgeon-years in the cranial cohort. Surgeons who devoted more than 75% of their practice to spinal or cranial surgery were termed highly specialized. Fully half of all neurosurgeons represented in the study were highly specialized in spinal surgery, whereas only 10% were highly specialized in cranial surgery.
When operating in their specialty, highly specialized surgeons had a lower than expected rate of mortality. Highly specialized spinal surgeons performed 75% of all spinal surgeries, which accounted for 57% of all spinal surgery deaths. Highly specialized cranial surgeons performed 25% of all cranial surgeries, which accounted for 15% of all cranial surgery deaths. Both types of specialists had lower patient mortality rates per surgeon than less specialized surgeons did.
These inverse relationships between specialization and mortality were noted across all levels of surgeon total volume in a stepwise fashion. The same was true for the co-primary outcome of adverse discharge disposition, which was defined as discharge to a short-term hospital, skilled nursing facility, intermediate care facility, home health care, another nursing or rehabilitation facility or death.
As neurosurgeon spinal specialization increased from the 25th percentile to the 75th percentile, there was a 27% reduction in the predicted probability of mortality and a 10% reduction in the predicted probability of adverse discharge disposition. The corresponding figures for cranial specialization were 15% and 6%.
The researchers note that case volume correlates with outcomes, but the new findings about specialization provide neurosurgeons another opportunity to improve mortality and morbidity. Rather than simply trying to increase the quantity of procedures one performs, it may be more feasible to establish a division of labor with partners such that each surgeon maintains a more specialized practice.