Serum 25-Hydroxyvitamin D Levels and Longitudinal Changes in Muscle Mass and Function in Peritoneal Dialysis...

Data regarding to how serum 25 hydroxyvitamin D (25(OH)D) levels affect muscle mass and function in end-stage renal disease (ESRD) patients have led to inconclusive results. The main goal of this research was to examine the relationship between 25(OH)D levels and the risk of deterioration in muscle mass and function among ESRD patients on continuous ambulatory peritoneal dialysis (CAPD). Eligible ESRD patients on CAPD were prospectively included, and followed up at 3-mo intervals in Ningbo No. 2 Hospital, the tertiary care center in the Ningbo region, Zhejiang Province, China for 12 mo. The mean 25(OH)D level <20 ng/mL of all visits during the 12-mo follow-up period was the exposure of interest. Primary outcome was defined as the deterioration of muscle mass and function at the end of the 12-mo follow-up. The absolute difference with 95% confidence interval (CI) of the incidence of deterioration of muscle mass and function between the groups with mean 25(OH)D<20 ng/mL and ≥20 ng/mL were estimated. The relationship between 25(OH)D levels and the risk of deterioration in muscle mass and function was examined by employing multivariate logistic regression models. Participants with 25(OH)D<20 ng/mL or 25(OH)D≥20 ng/mL in each visit were included as a sensitivity analysis. Subgroup analysis was conducted based on the age (<60 y and ≥60 y). Two hundred twenty-one eligible participants were included for the final statistical analysis. Among these 221 participants, patients with the mean 25(OH)D<20 ng/mL was 64.7% (143/221). During the 12-mo follow-up period, the incidence of deterioration in muscle mass and function was 37.6% (83/221). Compared to paticipants with mean 25(OH)D≥20 ng/mL, the incidence in paticipants with mean 25(OH)D<20 ng/mL was significantly higher (46.2% vs 21.8%, p<0.001), with an absolute difference of 24% (95%CI 12-37%). After adjustment for potential confounding factors, mean 25(OH)D<20 ng/mL was still associated with increased risk of the deterioration in muscle mass and function (OR=3.18, 95%CI 1.51-6.70, p=0.002). The association was consistent in the sensitivity analysis (OR=3.22, 95%CI 1.49-6.97, p=0.003). In subgroup analysis, the relationship between mean 25(OH)D<20 ng/mL and the deterioration in muscle mass and function remained consistent (OR=5.59, 95%CI 1.82-17.15, p=0.003) in paticipants with age ≥60 y; however, no significant relationship was identified in patients with age <60 y (OR=2.05, 95%CI 0.72-5.84, p=0.18). Our study demonstrated that lower serum 25(OH)D levels were significantly associated with an increased risk of the deterioration in muscle mass and function in ESRD patients on CAPD, especially in elderly individuals, implicating that vitamin D supplementation might represent an effective way to prevent and treat sarcopenia, frailty and their clinical complications. However, due to inherent limitations in the study, further research is necessary to establish a definitive causal relationship.