Risk of Intradialytic Hypotension by Day of the Week in Maintenance Hemodialysis.

Intradialytic hypotension (IDH) is a common complication of hemodialysis (HD) and is associated with a higher risk of cardiovascular (CV) events and mortality. CV events are more common on the days of HD, especially following the longer interdialytic interval. We investigated the risk of IDH according to day of HD in adults undergoing in-center, thrice-weekly HD in the Hemodialysis (HEMO) Study (N = 1,837 patients; n = 64,474 sessions), and the DaVita Clinical Research biorepository [BioReG]) (N = 952 patients; n = 61,197 sessions). Random effects logistic regression models assessed the risk of IDH (defined as nadir intra-HD systolic blood pressure [SBP] <90 mm Hg if pre-HD SBP <160 mm Hg, or <100 mm Hg if pre-HD SBP ≥160 mm Hg [Nadir90/100 definition]) according to HD day (Mon/Tue [HD1]; Wed/Thu [HD2]; Fri/Sat [HD3]). Alternative definitions of IDH were explored. Nadir90/100 occurred in 14% of HEMO and 18% of BioReG sessions. A monotonic increase in the risk of IDH was observed for HD2 and HD3, compared with HD1, for all IDH definitions in both cohorts. Compared with HD1, HD2 was associated with a 10% higher risk of Nadir90/100 (adjusted odds ratio, 1.10; 95% CI, 1.03-1.17) and HD3 was associated with a 31% higher risk (adjusted odds ratio, 1.31; 95% CI, 1.19-1.45) in HEMO, with consistent results in BioReG. We observed a monotonic increased risk of IDH with later days of the dialytic week in two separate cohorts. Further research to determine the underlying mechanisms is necessary to guide strategies for IDH prevention.