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Abstract: PO1056

Time of Hemodialysis and Risk of Intradialytic Hypotension and Intradialytic Hypertension

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis


  • Alostaz, Murad, University of California Los Angeles, Los Angeles, California, United States
  • Correa, Simon, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Waikar, Sushrut S., Boston Medical Center, Boston, Massachusetts, United States
  • McCausland, Finnian R., Brigham and Women's Hospital, Boston, Massachusetts, United States

Blood pressure (BP) fluctuates throughout the day following a circadian pattern. BP control is of utmost importance in patients with ESRD undergoing hemodialysis (HD), and both intradialytic hypotension (IDH) and intradialytic hypertension (HTN) are associated with adverse CV events and death. Whether the risk of IDH and intradialytic HTN varies according to the time of the day of the HD session is unknown.


Random effects logistic regression models examined the association of HD start time (before 9:00 am [timecat1], 9:00 am to 12:00 pm [timecat2], and after 12:00 PM [timecat3]) with IDH and intradialytic HTN among adults undergoing thrice-weekly maintenance HD (N= 1,938 patients/n=64,503 sessions from the Hemodialysis [HEMO] Study, and N=3,408 patients/n=33,590 from a contemporary large dialysis organization [LDO]). IDH was defined as nadir intra-HD SBP <90mmHg if pre-HD SBP <160mmHg or <100mmHg if pre-HD SBP ≥160mmHg, and intradialytic HTN was defined as any increase in post-HD SBP compared to pre-HD SBP. Models were adjusted for demographics, CV comorbidities, HD dose, HD flux, pre-HD BUN, pre-HD SBP, UFR, HD vintage and HD session length.


Mean age was 58 years and 56% were female in HEMO; mean age was 63 years and 42% were female in LDO. Compared to timecat1, timecat2 and timecat3 were associated with with a 9% (aOR 0.91, 95% CI 0.82-1.01) and a 17% (aOR 0.83, 95% CI 0.75-0.94) lower risk of IDH in HEMO, respectively (Fig 1A). Conversely, compared to timecat1, a monotonic increase in the risk of intradialytic HTN was observed for timecat2 (aOR 1.14, 95% CI 1.05-1.24) and timecat3 (aOR 1.40, 95% CI 1.28-1.53) in HEMO (Fig1B). These findings were consistent in LDO (Fig 1).


In two diverse and large cohorts of HD, we observed a monotonic decrease in the risk of IDH and a monotonic increase in the risk of intradialytic HTN as HD start time progressed throughout the day. Whether HD treatment allocation to certain times of the day in hypotensive-prone or hypertensive-prone patients improves outcomes deserves further investigation.