Effect of monthly vitamin D supplementation on antibiotic prescribing in older adults: a post hoc analysis of a randomized controlled trial

• Published in: The American journal of clinical nutrition Vol. 114; no. 1; pp. 314 - 321
• Main Authors: Wu, Zhenqiang, Camargo, Carlos A, Sluyter, John, Waayer, Debbie, Toop, Les, Scragg, Robert
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-07-2021; American Society for Clinical Nutrition, Inc
• Subjects: 25-hydroxyvitamin D; Adults; Aged; Aged, 80 and over; Aging; Anti-Bacterial Agents - administration & dosage; antibiotic prescribing; Antibiotics; bolus dose; Calciferol; Dietary Supplements; Double-Blind Method; Drug Prescriptions; Female; Humans; Male; Mathematical models; Middle Aged; Minority & ethnic groups; older adults; Older people; Placebos; randomized controlled trial; Supplements; Tetracyclines; Vitamin D; Vitamin D - administration & dosage; vitamin D supplementation; Vitamin D3; bolus dose; RCT; 25-hydroxyvitamin D; antibiotic prescribing; older adults; IRR; ViDA; 25(OH)D; vitamin D supplementation; randomized controlled trial
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/nqab015

Observational studies have reported that low vitamin D status is associated with increased risk of antibiotic use. However, trials on the effect of vitamin D supplementation on antibiotics are limited and inconclusive.
The main objective of this study was to determine the effect of monthly vitamin D supplementation on the proportion of adults with ≥1 prescriptions of antibiotics. The secondary outcomes were to determine the effect of monthly vitamin D supplementation on the number of antibiotic prescriptions and the number of days on antibiotics.
This was a post hoc analysis of a randomized, double-blinded, placebo-controlled trial with community-based older adults who were randomly assigned to receive monthly 100,000 IU of vitamin D or identical placebo. All analyses were based on the principle of “intention to treat.” RR from log-binomial models and the incidence rate ratio (IRR) from negative binomial models were estimated for primary and secondary outcomes after adjusting for age, sex, and ethnicity.
A total of 5108 participants aged 50–84 y were randomly assigned to vitamin D supplementation (n = 2558) or placebo (n = 2550) groups. During a median follow-up of 3.3 y, 4211 (82%) participants were prescribed antibiotics. There was no difference in the proportion of participants prescribed antibiotics between vitamin D (82%) and placebo (83%) groups (adjusted RR: 0.99; 95% CI: 0.97, 1.01; P = 0.42). Similarly, the number of antibiotic prescriptions per person-year did not differ between the 2 treatment groups (adjusted IRR: 0.98; 95% CI: 0.93, 1.04; P = 0.58). However, the number of days on antibiotics per person-year was significantly lower in the vitamin D group (mean ± SEM: 15 ± 0.7) compared with the placebo group (mean ± SEM: 17 ± 0.8) (adjusted IRR: 0.90; 95% CI: 0.82, 0.98; P = 0.01), especially for the tetracyclines (IRR: 0.65; 95% CI: 0.50, 0.85; P = 0.002).
Long-term, monthly, high-dose vitamin D3 supplementation did not prevent antibiotic prescribing in older adults, but the vitamin D group had fewer days per person-year on antibiotics. Further research is required to replicate these findings. This trial was registered at www.anzctr.org.au as ACTRN12611000402943.