Oral vitamin D supplementation on the prevention of peritoneal dialysis-related peritonitis: A pilot randomised controlled trial

Objective: Peritoneal dialysis (PD)-related peritonitis is independently associated with low serum 25-hydroxy vitamin D [25(OH)D] levels. Our objective is to examine the feasibility of conducting a large, randomised controlled trial to determine the effects of vitamin D supplementation on the risk of PD-related peritonitis. Design: Pilot, prospective, open-label randomised controlled trial. Setting: Peking University First Hospital, China. Participants: Patients receiving PD who had recovered from a recent episode of peritonitis between 30 September 2017 and 28 May 2020. Interventions: Oral natural vitamin D supplementation (2000 IU per day) versus no vitamin D supplementation for 12 months. Primary and secondary outcome measures: Primary outcomes were feasibility (recruitment success, retention, adherence, safety) and fidelity (change in serum 25(OH)D level during follow-up) for a large, randomised controlled trial in the future to determine the effects of vitamin D on PD-related peritonitis. Secondary outcomes were time to peritonitis occurrence and outcome of subsequent peritonitis. Results: Overall, 60 among 151 patients were recruited (recruitment rate was 39.7%, 95% CI 31.9-47.5%, recruitment rate among eligible patients was 61.9%, 95% CI 52.2-71.5%). Retention and adherence rates were 100.0% (95% CI 100.0-100.0%) and 81.5% (95% CI 66.8-96.1%), respectively. During follow-up, serum 25(OH)D levels increased in the vitamin D (VD) group (from 19.25 +/- 10.11 nmol/L to 60.27 +/- 23.29 nmol/L after 6 months, p < 0.001, n = 31), and remained higher (p < 0.001) than those in the control group (n = 29). No differences were observed between the two groups with respect to time to subsequent peritonitis (hazard ratio 0.85, 95% CI 0.33-2.17) or any of the peritonitis outcomes. Adverse events were uncommon. Conclusions: A randomised controlled trial of the effect of vitamin D supplementation on peritonitis occurrence in patients receiving PD is feasible, safe and results in adequate serum 25(OH)D levels.