Predictors of Intradialytic Symptoms: An Analysis of Data From the Hemodialysis Study

Background: Most patients receiving maintenance hemodialysis (HD) experience adverse symptoms, which are associated with decreased quality of life. Despite decades of experience, our understanding of causes of HD symptoms remains limited. We aimed to identify modifiable patient- and HD-related predictors of intradialytic symptoms. Study Design: Prospective cohort. Setting & Participants: We leveraged patientlevel (n = 1,838) and HD session-level (n = 64,797) data from the Hemodialysis Trial. Exposure: Pre-HD serum urea nitrogen (SUN) level, pre-HD systolic blood pressure (SBP), intradialytic SBP decline, and ultrafiltration rate (UFR). Outcomes: Intra-HD symptoms, including cramps, nausea, chest pain, headache, and lightheadedness. Analytical Approach: Random-effects logistic regression models. Results: Overall, symptoms occurred in 10.7% of HD sessions. Higher pre-HD SUN level (per 10 mg/dL) was associated with higher adjusted odds of muscle cramping and lightheadedness (adjusted ORs [aORs] of 1.20 [95% CI, 1.17-1.22] and 1.13 [95% CI, 1.08-1.18], respectively). SBP decline (from the predialysis value to the dialysis session nadir, per each 10-mm Hg decrease) was associated with greater risk for muscle cramping, headache, chest pain, vomiting, and lightheadedness (the largest aORs were for the 2 latter symptoms: 1.24 [95% CI, 1.20-1.28] and 1.37 [95% CI, 1.33-1.42], respectively). Higher UFR (per 1 mL/kg/h) was associated with greater odds of cramping (aOR, 1.03; 95% CI, 1.02-1.03). Conversely, higher pre-HD SBP (per 10 mm Hg) was associated with reduced risk for vomiting (aOR, 0.88; 95% CI, 0.85-0.92) and lightheadedness (aOR, 0.82; 95% CI, 0.80-0.85). Limitations: Measured osmolality, dialysate prescription data, and time stamps for symptom occurrence were not available. Clinical trial data may not be broadly generalizable. Conclusions: Higher pre-HD SUN level, UFR, pre-HD SBP, and SBP decline are independently associated with different patterns of adverse intradialytic symptoms. Recognition that different symptoms may have variable causes may allow tailoring of personalized treatments in future interventional studies.