title: The "July phenomenon" for neurosurgical mortality and complications in teaching hospitals: an analysis of more than 850,000 neurosurgical patients in the nationwide inpatient sample database, 1998 to 2008.
abstract: BACKGROUND
  The evidence of or against the presence of a 'July phenomenon' in resident teaching hospitals has been inconsistent. Moreover, there are limited data on the "July phenomenon" in the field of neurosurgery.
  
  
  OBJECTIVE
  To determine whether a "July phenomenon" exists for neurosurgical mortality or complications.
  
  
  METHODS
  A search of the National Inpatient Sample database from 1998 to 2008 was performed for all admissions for International Classification of Diseases, 9th Revision codes corresponding to nontraumatic hemorrhage, central nervous system (CNS) trauma, CNS tumor, and hydrocephalus. Generalized linear mixed-model analysis was performed, adjusted for patient demographics and hospital characteristics, for the outcomes of mortality and complications for the month of July compared with all other months in teaching hospitals.
  
  
  RESULTS
  Generalized linear mixed-model analysis demonstrated that the risk of dying in the month of July vs any other month in a teaching hospital was not statistically different for any of the 4 diagnoses: nontraumatic hemorrhage (P = .071), CNS trauma category (P = .485), CNS tumor category (P = .578), hydrocephalus category (P = .1505). Moreover, the risk of any complication in the month of July vs any other month in a teaching hospital was not statistically different for any of the 4 diagnoses: nontraumatic hemorrhage (P = .529), CNS trauma category (P = .378), CNS tumor category (P = .461), and hydrocephalus category (P = .441). The same findings were true in an analysis of nonteaching hospitals performed as a control.
  
  
  CONCLUSIONS
  No "July phenomenon" was found for neurosurgical mortality or complications in patients with nontraumatic hemorrhage, CNS trauma, CNS tumor, or hydrocephalus.
authors.affiliation: Department of Neurosurgery, University of Florida, Gainesville, Florida 32610, USA.
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Weaver
authors.forename: Dan
authors.initials: D
authors.lastname: Neal
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hoh
authors.forename: J
authors.initials: J
authors.lastname: Mocco
authors.forename: Fred G
authors.initials: FG
authors.lastname: Barker
authors.forename: Brian L
authors.initials: BL
authors.lastname: Hoh
mesh_terms: D016208:Databases, Factual; D017052:Hospital Mortality; D006784:Hospitals, Teaching / Q000592:standards / Q000706:statistics & numerical data*; D006801:Humans; D009493:Neurosurgery / Q000592:standards / Q000706:statistics & numerical data*; D019635:Neurosurgical Procedures / Q000401:mortality*; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D012621:Seasons