Seasonal variations in outcomes after kidney transplantation: UNOS review of 336,330 transplants

Introduction: 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). Conclusion: 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.