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

Autor: Adrian R. Martineau, Benoit Aigret, Richard Ostler, Michelle Newton, Michael Hill, Julian Peto, Laurette Bukasa, James Peto Wild, Oliver Gillie, Irwin Nazareth, Peter Sasieni, Clare Gilham, Christine Rake
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Health Technology Assessment, Vol 24, Iss 10 (2020)
ISSN: 2046-4924
1366-5278
Popis: Background Randomised controlled trials demonstrating improved longevity are needed to justify high-dose vitamin D supplementation for older populations. Objectives To demonstrate the feasibility of a large trial (n ≈ 20,000) of high-dose vitamin D in people aged 65–84 years through general practitioner (GP) practices, and to cluster randomise participating practices between open-label and double-blind randomisation to compare effects on recruitment, compliance and contamination. Design Twenty GP practices were randomised in matched pairs between open-label and double-blind allocation. 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. Randomisation by telephone followed receipt of a serum corrected calcium assay confirming eligibility ( Setting GP practices in England. Participants 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. Interventions There was a 24-month treatment period: 12 monthly doses (100,000 IU of vitamin D3 or placebo as 5 ml oily solution) were posted after randomisation and at 1 year (100,000 IU per month corresponds to 3300 IU per day). Reminders were sent monthly by e-mail, text message or post. Main outcome measures Recruitment, compliance, contamination and change in circulating 25-hydroxyvitamin D [25(OH)D] from baseline to 2 years. Results Participation rates (randomised/invited) were 15.0% in open practices and 13.4% in double-blind practices (p = 0.7). The proportion still taking study medication at 2 years was 91.2% in open practices and 89.2% in double-blind practices (p = 0.4). The proportion of control participants taking > 400 IU vitamin D per day at 2 years was 5.0% in open practices and 4.8% in double-blind practices. Mean serum 25(OH)D concentration was 51.5 nmol/l [95% confidence interval (CI) 50.2 to 52.8 nmol/l] with 82.6% of participants Conclusions A trial could recruit 20,000 participants aged 65–84 years through 200 GP practices over 2 years. Approximately 80% would be expected to adhere to allocated treatment (vitamin D or placebo) for 5 years. The trial could be conducted entirely by e-mail in participants aged Trial registration Current Controlled Trials ISRCTN46328341 and EudraCT database 2011-003699-34. Funding 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. See the NIHR Journals Library website for further project information.
Databáze: OpenAIRE
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