SO087RISK OF INTRADIALYTIC HYPOTENSION BY DAY OF THE WEEK IN MAINTENANCE HEMODIALYSIS

Abstract

Abstract Background and Aims Intradialytic hypotension (IDH) affects up to 50% of maintenance hemodialysis (HD) patients and is associated with a higher risk of cardiovascular (CV) events and mortality. CV events are more common on the days of dialysis and are most pronounced following the longer interdialytic interval. We wished to investigate if the rates of IDH differed according to dialysis day. Method We examined data from adult patients undergoing in-center thrice-weekly maintenance HD (N= 975 patients/n=59,004 sessions from a large dialysis organization [LDO] and N=1,838 patients/n=64,407 sessions from the Hemodialysis [HEMO] Study). We fit random effects logistic regression models to determine the association of day of HD (Mon/Tue [HD1]; Wed/Thu [HD2]; Fri/Sat [HD3]) with various definitions of IDH. Models were adjusted for age, sex, race, Kt/V, membrane flux, heart failure, peripheral vascular disease, diabetes, access type (catheter vs. fistula vs. graft), pre-dialysis blood urea nitrogen, ultrafiltration rate, pre-HD systolic blood pressure (SBP). IDH definitions included Nadir90 (nadir intra-HD SBP <90mmHg), Nadir90/100 (nadir intra-HD SBP <90mmHg if pre-HD SBP <160mmHg or <100mmHg if pre-HD SBP ≥160mmHg), Fall20 (pre-SBP minus nadir SBP ≥20mmHg) and Fall30 (pre-SBP minus nadir SBP ≥30mmHg). Results Mean age was 60 years, 44% were female and 38% were black in the LDO cohort, while mean age was 58 years, 56% were female and 63% were black in HEMO. Nadir90 occurred in 15% of LDO and 11% of HEMO sessions; Nadir90/100 occurred in 18% of LDO and 14% of HEMO sessions; Fall20 occurred in 76% of LDO and 68% of HEMO sessions; Fall30 occurred in 60% of LDO and 50% of HEMO sessions. Overall, a monotonic increase in the risk of IDH was observed for HD2 and HD3 compared with HD1 for all IDH definitions in both cohorts (see Table and Figure). Conclusion We observed a consistent monotonic increase in the risk of IDH for HD2 and HD3, compared with HD1 in two separate cohorts of maintenance HD patients. Potential explanations may relate to progressive reduction in post-HD weight during the dialytic week, or perhaps more aggressive ultrafiltration in advance of the longer interval. Further research to determine the underling mechanisms is necessary to guide practicing nephrologists when individualizing the HD prescription.