title: Seasonal variations in transition, mortality and kidney transplantation among patients with end-stage renal disease in the USA.
abstract: BACKGROUND
  Seasonal variations may exist in transitioning to dialysis, kidney transplantation and related outcomes among end-stage renal disease (ESRD) patients. Elucidating these variations may have major clinical and healthcare policy implications for better resource allocation across seasons.
  
  
  METHODS
  Using the United States Renal Data System database from 1 January 2000 to 31 December 2013, we calculated monthly counts of transitioning to dialysis or first transplantation and deaths. Crude monthly transition fraction was defined as the number of new ESRD patients divided by all ESRD patients on the first day of each month. Similar fractions were calculated for all-cause and cause-specific mortality and transplantation.
  
  
  RESULTS
  The increasing trend of the annual transition to ESRD plateaued during 2009-2012 (n = 126 264), and dropped drastically in 2013 (n = 117 372). Independent of secular trends, monthly transition to ESRD was lowest in July (1.65%) and highest in January (1.97%) of each year. All-cause, cardiovascular and infectious mortalities were lowest in July or August (1.32, 0.58 and 0.15%, respectively) and highest in January (1.56, 0.71 and 0.19%, respectively). Kidney transplantation was highest in June (0.33%), and this peak was mainly attributed to living kidney transplantation in summer months. Transplant failure showed a similar seasonal variation to naïve transition, peaking in January (0.65%) and nadiring in September (0.56%).
  
  
  CONCLUSIONS
  Transitioning to ESRD and adverse events among ESRD people were more frequent in winter and less frequent in summer, whereas kidney transplantation showed the reverse trend. The potential causes and implications of these consistent seasonal variations warrant more investigation.
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Obi
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.|Fielding School of Public Health at UCLA, Los Angeles, CA, USA.|Los Angeles Biomedical Research Institute at Harbor-UCLA, Torrance, CA, USA.
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Elani
authors.initials: E
authors.lastname: Streja
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Connie M
authors.initials: CM
authors.lastname: Rhee
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Uttam G
authors.initials: UG
authors.lastname: Reddy
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Soohoo
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Ravel
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Amy S
authors.initials: AS
authors.lastname: You
authors.affiliation: Harold Simmons Center for Kidney Disease Research and Epidemiology, Division of Nephrology and Hypertension, University of California Irvine, Orange, CA, USA.
authors.forename: Jennie
authors.initials: J
authors.lastname: Jing
authors.affiliation: Kaiser Permanente of Southern California, Los Angeles, CA, USA.
authors.forename: John J
authors.initials: JJ
authors.lastname: Sim
authors.affiliation: Biostatistics, Epidemiology & Research Design Unit, Institute for Clinical and Translational Science, University of California Irvine, Irvine, CA, USA.
authors.forename: Danh V
authors.initials: DV
authors.lastname: Nguyen
authors.affiliation: Deptartment of Statistics, Program in Public Health, University of California Irvine, Irvine, CA, USA.
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Gillen
authors.affiliation: Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.|Kidney Epidemiology and Cost Center, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Saran
authors.affiliation: Arbor Research Collaborative for Health, Ann Arbor, MI, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Robinson
authors.affiliation: Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA.|Nephrology Section, Memphis VA Medical Center, Memphis, TN, USA.
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000401:mortality* / Q000628:therapy*; D016030:Kidney Transplantation / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000706:statistics & numerical data; D012621:Seasons; D017211:Treatment Failure; D014481:United States / Q000453:epidemiology
keywords: ESRD; hemodialysis; kidney transplantation; mortality; peritoneal dialysis