title: The effect of July admission on inpatient morbidity and mortality after adult spinal deformity surgery.
abstract: BACKGROUND
  Some studies have suggested patients who undergo surgery in July have worse outcomes compared to patients treated during other months. The purpose of this study is to compare inpatient morbidity and mortality among patients who underwent adult spinal deformity (ASD) surgery in July with those who underwent surgery in other months.
  
  
  METHODS
  Admission data for patients who underwent ASD surgery were extracted from the Nationwide Inpatient Sample for the years 2002 to 2011. Only adult patients (over 21 years of age) and elective admissions to teaching hospitals were included. A multivariable regression analysis was performed to examine the independent effect of July admissions on overall complications, major complications, and inpatient mortality.
  
  
  RESULTS
  A total of 27,794 patients were identified, with 2,023 (7.8%) admitted in July and 25,771 (92.2%) in other months. Overall complication rates in July (43.1%) were not different from rates in other months (44.9%, p=0.468). Similarly, major complication rates were similar; 12.9% in July and 12.4% in other months (p=0.764). Mortality was not different between groups (p=0.807). After multivariable analysis, July admissions were not found to increase the odds of developing any complication (OR 0.94; 95% CI, 0.77 - 1.12; p=0.403), major complications (OR 1.04; 95% CI, 0.76 - 1.41; p=0.788) or inpatient mortality (OR 1.35; 95% CI, 0.31 - 5.84; p=0.684).
  
  
  CONCLUSIONS
  In this study of a nationwide database, patients who underwent ASD surgery in July did not have increased odds of developing a complication or inpatient mortality compared to patients admitted in other months.
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Rafael
authors.initials: R
authors.lastname: De la Garza-Ramos
authors.affiliation: Division of Spinal Surgery, NYU Medical Center-Hospital for Joint Diseases, New York City, New York.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Passias
authors.affiliation: Spine Surgery, Hospital for Special Surgery, New York City, New York.
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Schwab
authors.affiliation: Spine Surgery, Hospital for Special Surgery, New York City, New York.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lafage
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Sciubba
keywords: adult spinal deformity; complications; july effect; mortality; nationwide inpatient sample; teaching hospital