Volume-outcome relationship in neurotrauma care

Clinical article

Restricted access


A positive correlation between outcomes and the volume of patients seen by a provider has been supported by numerous studies. Volume-outcome relationships (VORs) have been well documented in the setting of both neurosurgery and trauma care and have shaped regionalization policies to optimize patient outcomes. Several authors have also investigated the correlation between patient volume and cost of care, known as the volume-cost relationship (VCR), with mixed results. The purpose of the present study was to investigate VORs and VCRs in the treatment of common intracranial injuries by testing the hypotheses that outcomes suffer at small-volume centers and costs rise at large-volume centers.


The authors performed a cross-sectional cohort study of patients with neurological trauma using the 2006 Nationwide Inpatient Sample, the largest nationally representative all-payer data set. Patients were identified using ICD-9 codes for subdural, subarachnoid, and extradural hemorrhage following injury. Transfers were excluded from the study. In the primary analysis the association between a facility's neurotrauma patient volume and patient survival was tested. Secondary analyses focused on the relationships between patient volume and discharge status as well as between patient volume and cost. Analyses were performed using logistic regression.


In-hospital mortality in the overall cohort was 9.9%. In-hospital mortality was 14.9% in the group with the smallest volume of patients, that is, fewer than 6 cases annually. At facilities treating 6–11, 12–23, 24–59, and 60+ patients annually, mortality was 8.0%, 8.3%, 9.5%, and 10.0%, respectively. For these groups there was a significantly reduced risk of in-hospital mortality as compared with the group with fewer than 6 annual patients; the adjusted ORs (and corresponding 95% CIs) were 0.45 (0.29–0.68), 0.56 (0.38–0.81), 0.63 (0.44–0.90), and 0.59 (0.41–0.87), respectively. For these same groups (once again using < 6 cases/year as the reference), there were no statistically significant differences in either estimated actual cost or duration of hospital stay.


A VOR exists in the treatment of neurotrauma, and a meaningful threshold for significantly improved mortality is 6 cases per year. Emergency and interfacility transport policies based on this threshold might improve national outcomes. Cost of care does not differ significantly with patient volume.

Abbreviations used in this paper:AIS = Abbreviated Injury Scale; CABG = coronary artery bypass graft; ICH = intracranial hemorrhage; LOS = length of stay; NIS = Nationwide Inpatient Sample; VCR = volume-cost relationship; VOR = volume-outcome relationship.

Article Information

Address correspondence to: Neil R. Malhotra, M.D., Department of Neurological Surgery, University of Pennsylvania, 3 Silverstein Pavilion, 3400 Spruce Street, Philadelphia, Pennsylvania 19104. email: NRM@UPHS.UPenn.edu.

Please include this information when citing this paper: published online December 14, 2012; DOI: 10.3171/2012.10.JNS12682.

© AANS, except where prohibited by US copyright law.



  • View in gallery

    Bar graph depicting the percentage of neurotrauma cases resulting in favorable dispositions (black bars), unfavorable dispositions, excluding death (white bars), and mortality (gray bars) at centers of varying size.



Bardach NSZhao SGress DRLawton MTJohnston SC: Association between subarachnoid hemorrhage outcomes and number of cases treated at California hospitals. Stroke 33:185118562002


Barker FG IICurry WT JrCarter BS: Surgery for primary supratentorial brain tumors in the United States, 1988 to 2000: the effect of provider caseload and centralization of care. Neuro Oncol 7:49632005


Barker FG IIKlibanski ASwearingen B: Transsphenoidal surgery for pituitary tumors in the United States, 1996–2000: mortality, morbidity, and the effects of hospital and surgeon volume. J Clin Endocrinol Metab 88:470947192003


Bennett KMVaslef SPappas TNScarborough JE: The volume-outcomes relationship for United States Level I trauma centers. J Surg Res 167:19232011


Birkmeyer JDDimick JB: Potential benefits of the new Leapfrog standards: effect of process and outcomes measures. Surgery 135:5695752004


Birkmeyer JDFinlayson EVBirkmeyer CM: Volume standards for high-risk surgical procedures: potential benefits of the Leapfrog initiative. Surgery 130:4154222001


Birkmeyer JDSiewers AEFinlayson EVAStukel TALucas FLBatista I: Hospital volume and surgical mortality in the United States. N Engl J Med 346:112811372002


Birkmeyer JDSkinner JSWennberg DE: Will volume-based referral strategies reduce costs or just save lives?. Health Aff (Millwood) 21:2342412002


Birkmeyer JDStukel TASiewers AEGoodney PPWennberg DELucas FL: Surgeon volume and operative mortality in the United States. N Engl J Med 349:211721272003


Demetriades DMartin MSalim ARhee PBrown CChan L: The effect of trauma center designation and trauma volume on outcome in specific severe injuries. Ann Surg 242:5125192005


Demetriades DMartin MSalim ARhee PBrown CDoucet J: Relationship between American College of Surgeons trauma center designation and mortality in patients with severe trauma (injury severity score > 15). J Am Coll Surg 202:2122152006


Frontera JAEgorova NMoskowitz AJ: National trend in prevalence, cost, and discharge disposition after subdural hematoma from 1998–2007. Crit Care Med 39:161916252011


Gooiker GAvan Gijn WPost PNvan de Velde CJHTollenaar RAEMWouters MWJM: A systematic review and meta-analysis of the volume-outcome relationship in the surgical treatment of breast cancer. Are breast cancer patients better of with a high volume provider?. Eur J Surg Oncol 36:Suppl 1S27S352010


Gooiker GAvan Gijn WWouters MWJMPost PNvan de Velde CJHTollenaar RAEM: Systematic review and meta-analysis of the volume-outcome relationship in pancreatic surgery. Br J Surg 98:4854942011


Goossens-Laan CAGooiker GAvan Gijn WPost PNBosch JLHRKil PJM: A systematic review and meta-analysis of the relationship between hospital/surgeon volume and outcome for radical cystectomy: an update for the ongoing debate. Eur Urol 59:7757832011


Gourin CGForastiere AASanguineti GKoch WMMarur SBristow RE: Impact of surgeon and hospital volume on short-term outcomes and cost of laryngeal cancer surgical care. Laryngoscope 121:85902011


Grumbach KAnderson GMLuft HSRoos LLBrook R: Regionalization of cardiac surgery in the United States and Canada. Geographic access, choice, and outcomes. JAMA 274:128212881995


Halm EALee CChassin MR: Is volume related to outcome in health care? A systematic review and methodologic critique of the literature. Ann Intern Med 137:5115202002


Hannan ELKilburn H JrBernard HO'Donnell JFLukacik GShields EP: Coronary artery bypass surgery: the relationship between inhospital mortality rate and surgical volume after controlling for clinical risk factors. Med Care 29:109411071991


Harmon JWTang DGGordon TABowman HMChoti MAKaufman HS: Hospital volume can serve as a surrogate for surgeon volume for achieving excellent outcomes in colorectal resection. Ann Surg 230:4044131999


Hastan DVandenbroucke JPvan der Mey AGL: A meta-analysis of surgical treatment for vestibular schwannoma: is hospital volume related to preservation of facial function?. Otol Neurotol 30:9759802009


Ho VAloia T: Hospital volume, surgeon volume, and patient costs for cancer surgery. Med Care 46:7187252008


Ho VPetersen LA: Estimating cost savings from regionalizing cardiac procedures using hospital discharge data. Cost Eff Resour Alloc 5:72007


Holt PJEPoloniecki JDLoftus IMMichaels JAThompson MM: Epidemiological study of the relationship between volume and outcome after abdominal aortic aneurysm surgery in the UK from 2000 to 2005. Br J Surg 94:4414482007


Joynt KEOrav EJJha AK: The association between hospital volume and processes, outcomes, and costs of care for congestive heart failure. Ann Intern Med 154:941022011


Kates SLMendelson DAFriedman SM: The value of an organized fracture program for the elderly: early results. J Orthop Trauma 25:2332372011


Koelemay MJVahl AC: Meta-analysis and systematic review of the relationship between volume and outcome in abdominal aortic aneurysm surgery (Br J Surg 2007; 94: 395-403). Br J Surg 94:10412007. (Letter)


Konety BRDhawan VAllareddy VO'Donnell MA: Association between volume and charges for most frequently performed ambulatory and nonambulatory surgery for bladder cancer. Is more cheaper?. J Urol 172:105610612004


Kuo EYChang YWright CD: Impact of hospital volume on clinical and economic outcomes for esophagectomy. Ann Thorac Surg 72:111811242001


Markar SRKarthikesalingam AThrumurthy SLow DE: Volume-outcome relationship in surgery for esophageal malignancy: systematic review and meta-analysis 2000–2011. J Gastrointest Surg 16:205510632012


Nathens ABMaier RV: The relationship between trauma center volume and outcome. Adv Surg 35:61752001


Oyetunji TAHaider AHDowning SRBolorunduro OBEfron DTHaut ER: Treatment outcomes of injured children at adult level 1 trauma centers: are there benefits from added specialized care?. Am J Surg 201:4454492011


Smith ERButler WEBarker FG II: In-hospital mortality rates after ventriculoperitoneal shunt procedures in the United States, 1998 to 2000: relation to hospital and surgeon volume of care. J Neurosurg 100:2 Suppl Pediatrics90972004


Solheim OSalvesen ØCappelen JJohannesen TB: The impact of provider surgical volumes on survival in children with primary tumors of the central nervous system—a population-based study. Acta Neurochir (Wien) 153:121912292011


Sosa JABowman HMGordon TABass EBYeo CJLillemoe KD: Importance of hospital volume in the overall management of pancreatic cancer. Ann Surg 228:4294381998


Swisher SGDeford LMerriman KWWalsh GLSmythe RVaporicyan A: Effect of operative volume on morbidity, mortality, and hospital use after esophagectomy for cancer. J Thorac Cardiovasc Surg 119:112611322000


van Gijn WGooiker GAWouters MWJMPost PNTollenaar RAEMvan de Velde CJH: Volume and outcome in colorectal cancer surgery. Eur J Surg Oncol 36:Suppl 1S55S632010


Vespa PDiringer MN: High-volume centers. Neurocrit Care 15:3693722011


Wilson AMarlow NEMaddern GJBarraclough BCollier NADickinson IC: Radical prostatectomy: a systematic review of the impact of hospital and surgeon volume on patient outcome. ANZ J Surg 80:24292010




All Time Past Year Past 30 Days
Abstract Views 69 69 24
Full Text Views 121 121 7
PDF Downloads 95 95 3
EPUB Downloads 0 0 0


Google Scholar