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.

Conclusion: No "July phenomenon" was found for neurosurgical mortality or complications in patients with nontraumatic hemorrhage, CNS trauma, CNS tumor, or hydrocephalus.