Preoperative Dialysis Dose and Postoperative Outcomes in Patients Receiving Maintenance Hemodialysis.

Background: Little is known about preoperative hemodialysis dosing for patients with end-stage kidney disease. We assessed whether changes in preoperative hemodialysis dose (compared to and controlling for baseline dose) are associated with postoperative mortality in patients receiving maintenance hemodialysis.

Methods: We identified fee-for-service Medicare beneficiaries receiving hemodialysis for end-stage kidney disease who underwent surgical procedures between January 1, 2011, and November 30, 2020. Follow-up ended December 31, 2020. The primary exposure was preoperative change in Kt/Vurea, defined as the difference between the Kt/Vurea in the hemodialysis session proximal to the procedure and the mean Kt/Vurea for the preceding 180 days. The primary outcome was postoperative 30-day mortality. The relation between preoperative change in Kt/Vurea and the primary outcome was modeled using a Cox proportional hazards regression model, adjusted for mean and standard deviation of Kt/Vurea in the 180 days preceding the procedure, and for other covariates.

Results: Among 151,240 procedures (median age, 65 years [25%-75% range, 56-73], 63,437 (41.9%) in women), 31,825 (21.0%) had a preoperative change in Kt/Vurea of <-0.10, 43,790 (29.0%) had a preoperative change of -0.10 to < 0, 45,058 (29.8%) had a preoperative change of 0 to <+0.10, and 30,567 (20.2%) had a preoperative change of ≥+0.10. The median Kt/Vurea for the 180 days prior to the procedure was 1.58 (25th-75th percentiles, 1.45-1.74). In adjusted analysis, compared to patients with a preoperative change in Kt/Vurea of 0 to <+0.10, 30-day mortality was 1.50 (95% CI, 1.32, 1.70) times higher with a preoperative Kt/Vurea change of ≤-0.10 and 1.16 (95% CI, 1.02, 1.31) times higher with a preoperative Kt/Vurea change of -0.10 to < 0. Increases in preoperative Kt/Vurea that were greater than 0.10 were not significantly associated with 30-day mortality.

Conclusions: Among Medicare beneficiaries receiving maintenance hemodialysis, preoperative decreases in Kt/Vurea (compared to and controlling for mean Kt/Vurea) were significantly associated with postoperative mortality.