title: Seasonal variations in outcomes after kidney transplantation: UNOS review of 336,330 transplants.
abstract: BACKGROUND
  The "July effect" is a widely discussed phenomenon of worse patient outcomes at teaching hospitals in July due to inexperienced house staff.
  
  
  METHODS
  We conducted a retrospective review of Organ Procurement and Transplantation Network data from Oct 1, 1987 to June 30, 2011, including longitudinal censored data of 360,330 transplantations. Demographic and comorbid variables for donors and recipients were collected. Primary outcomes were graft loss, patient death, and delayed graft function. Secondary outcomes were surgical complications, length of stay, and graft rejection. We compared survival indicators (1-month, 1-, 3-, and 5-year survival and median survival times) for both grafts and patients. We also analyzed death-censored graft survival.
  
  
  RESULTS
  There were fewer July donors with diabetes (p = 0.003), hypertension (p = 0.000), and extended criteria (p<0.0001). Graft survival (p = 0.000), death-censored graft survival (p = 0.001), and patient survival (p = 0.002) were statistically higher in July. After adjusting the Cox model for extended criteria donors, there was no difference in outcomes (p>0.05 for graft, death-censored graft survival, and patient survival).
  
  
  CONCLUSIONS
  We conclude that there is no July effect. Initially identified, superior outcomes in July may be attributed to more conservative allografts selection in the beginning of the academic year.
authors.affiliation: Department of Surgery, Division of Transplant Surgery, Albert Einstein Medical Center, Philadelphia, Pennsylvania 19141, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Pang
authors.forename: Farah
authors.initials: F
authors.lastname: Karipineni
authors.forename: Heena
authors.initials: H
authors.lastname: Panchal
authors.forename: Stalin
authors.initials: S
authors.lastname: Campos
authors.forename: Jorge
authors.initials: J
authors.lastname: Ortiz
mesh_terms: D000328:Adult; D000368:Aged; D015897:Comorbidity; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D012189:Retrospective Studies; D012621:Seasons; D016019:Survival Analysis; D014019:Tissue Donors