Table 2

The number of providers that perform enough elective neurosurgical procedures over 3-year and 5-year periods to detect statistical outliers if the 30-day mortality rate is double the national average

Elective neurosurgery	National average mortality rate for elective neurosurgery (%)	Average annual no of procedures per surgeon/hospital (n)	Minimum sample size (80% power) (n)	Surgeons/hospitals achieving or exceeding minimum sample size
Elective neurosurgery		Average annual no of procedures per surgeon/hospital (n)	Minimum sample size (80% power) (n)	3 years (n, %)	5 years (n, %)
Surgeons
I. All procedures and major procedures
All procedures	0.4	96	2402	0/398 (0)	1/407 (0.2)
Major procedures	0.5	81	1989	0/390 (0)	1/399 (0.3)
Hospitals
I. All procedures and major procedures
All procedures	0.4	1481	2402	21/24 (87.5)	24/24 (100)
Major procedures	0.5	1192	1989	22/24 (91.7)	23/24 (95.8)
II. Cranial and spinal procedures
Cranial surgery	1.0	452	969	17/24 (70.8)	22/24 (91.7)
Spinal surgery	0.1	663	9423	0/24 (0)	0/24 (0)
III. Subspecialty procedures
General neurosurgery	0.7	39	1345	0/24 (0)	0/24 (0)
Functional	0.2	138	4567	0/24 (0)	0/24 (0)
Neuro-oncology	2.3	145	410	14/24 (58.3)	19/24 (79.2)
All CSF procedures	0.5	60	2176	0/24 (0)	0/24 (0)
CSF shunt procedures	0.4	40	2294	0/24 (0)	0/24 (0)
Skull base	0.7	101	1445	0/24 (0)	0/24 (0)
Neurovascular	0.7	54	1488	0/24 (0)	0/24 (0)
Simple spine	0.1	524	12 559	0/24 (0)	0/24 (0)
Complex spine	0.2	59	5925	0/24 (0)	0/24 (0)
Intradural spine	0.3	26	3519	0/24 (0)	0/24 (0)

CSF, cerebrospinal fluid.