Association between corrected serum calcium levels after dialysis and post-dialysis fatigue risk: a hospital-based case–control study

OBJECTIVE: Post-dialysis fatigue (PDF) is an important problem in patients undergoing maintenance hemodialysis (MHD); however, evidence of the association between serum calcium after dialysis and the risk of PDF is limited and controversial. We explored this association among patients receiving MHD. METHODS: We carried out a case–control study of patients in the dialysis unit of Dalian Municipal Central Hospital between December 2019 and January 2020, including 340 patients with PDF and 270 patients without PDF. PDF was assessed by a \validated self-administered questionnaire. Clinical variables were tested for multicollinearity using variance inflation factor analysis. Corrected serum calcium levels were categorized into three groups, with the lowest tertile used as the reference category. The odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for PDF risk were estimated using an unconditional logistic regression model. RESULT: After adjusting for potential confounders, corrected serum calcium levels showed a significant positive association with the risk of PDF (OR(T3vs.T1) = 1.61, 95% CI = 1.01–2.58). Notably, after stratification by age, corrected serum calcium was also positively associated with the risk of PDF in patients aged ≥ 65 years (OR(T3vs.T1) = 4.25, 95% CI 1.66–11.46). Furthermore, a significant linear trend and interaction were also observed (P < 0.05). DISCUSSION: Higher corrected serum calcium levels after dialysis might increase the risk of PDF among MHD patients. However, further studies are warranted to confirm these findings.