High-dose oral vitamin D supplementation and mortality in people aged 65-84 years: the VIDAL cluster feasibility RCT of open versus double-blind individual randomisation.

What Was Tested

Researchers studied Vitamin D, K2, Magnesium and Zinc in this randomized controlled trial publication.

Current Controlled Trials ISRCTN46328341 and EudraCT database 2011-003699-34.

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 10.

Who Took Part

The study group was 1615 patients.

The age groups tagged for this paper are older adults and people over 80, both men and women.

Within each practice, patients were individually randomised to vitamin D or control (i.e. no treatment or placebo).

Participants were invited to attend their GP practice to provide a blood sample and complete a lifestyle questionnaire at recruitment and again at 2 years.

How the Study Was Run

In design terms this was a randomized, double-blind, open-label and placebo-controlled study.

The patients were allocated by chance, so the Vitamin D, K2, Magnesium and Zinc group and the comparison group should start out alike.

Blinding on both sides kept the patients and researchers unaware of who received Vitamin D, K2, Magnesium and Zinc.

Being open-label, the Vitamin D, K2, Magnesium and Zinc study did not mask who received what.

The comparison arm used a placebo, so changes seen with Vitamin D, K2, Magnesium and Zinc could be set against what happens without it.

Twenty GP practices were randomised in matched pairs between open-label and double-blind allocation.

Treatment compliance was reported by quarterly follow-up forms sent and returned by e-mail or post (participant choice).

GP visits and infections were abstracted from GP records.

Recruitment opened in October 2013 and closed in January 2015.

A total of 1615 registered patients aged 65-84 years were randomised: 407 to vitamin D and 421 to no treatment in open practices; 395 to vitamin D and 392 to placebo in blind practices.

What Was Measured

This project was funded by the National Institute for Health Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 10.

PubMed files the paper under topics including Dietary Supplements, Feasibility Studies, General Practitioners, Mortality, Patient Compliance, Surveys and Questionnaires and United Kingdom.

The authors tagged it with the keywords CLUSTER RANDOMISATION, GP PRACTICE, RANDOMISED TRIAL and VITAMIN D.

What This Means in Plain Language

The paper is a randomized, double-blind and open-label study of Vitamin D, K2, Magnesium and Zinc in 1615 patients.

With several hundred people or more, it is a fairly large study for this kind of research.

Results are reported in around 10 sentences of the abstract; we leave them to the paper itself rather than summarise them.

The publication is from 2020 (Health technology assessment (Winchester, England)), a journal based in England.

More context: the Vitamin D, K2, Magnesium and Zinc compound page, all human trials.