MedicalResearch.com Interview with:
David Jolliffe, PhD
Centre for Primary Care and Public Health
Barts and the London School of Medicine and Dentistry
MedicalResearch.com: What is the background for this study?
Response: Asthma affects more than 300 million people worldwide and is estimated to cause almost 400,000 deaths annually. Asthma deaths arise primarily during episodes of acute worsening of symptoms, known as attacks or ‘exacerbations’, which are commonly triggered by viral upper respiratory infections. Vitamin D is thought to protect against such attacks by boosting immune responses to respiratory viruses and dampening down harmful airway inflammation.
Several clinical trials have tested whether vitamin D supplementation might protect against asthma attacks, but individually their results are inconclusive. In the current study, we pooled raw data from 955 asthma patients who took part in 7 separate trials, which allowed us to answer two questions:
1, Does vitamin D protects against asthma attacks overall, when data from all trials are pooled?
2, Do people who have lower vitamin D levels to start with particularly benefit from supplementation?
MedicalResearch.com: What are the main findings?
Response: Our ‘overall’ analysis showed that vitamin D supplementation resulted in a 30% reduction in the rate of asthma attacks treated with steroid tablets or injections (from 0.43 events per person per year to 0.30), and a 50% reduction in asthma attacks requiring Emergency Department attendance and/or hospitalisation (from 6% to 3%).
Additionally, vitamin D supplementation was found to have a strong and statistically-significant protective effect in participants who had low vitamin D levels to start with. These participants saw a 55 per cent reduction in the rate of asthma exacerbations requiring treatment with steroid tablets or injections – from 0.42 events per person per year to 0.19. No statistically significant benefit of vitamin D was seen among those who had higher vitamin D levels at baseline.
MedicalResearch.com: What should readers take away from your report?
Response: These results add to the ever-growing body of evidence that vitamin D supplementation may have a role in reducing risk of severe asthma attacks. Vitamin D is safe to take and relatively inexpensive so supplementation represents a potentially cost-effective strategy to reduce this problem.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Our results are largely based on data from adults with mild to moderate asthma: children and adults with severe asthma were relatively under-represented in the dataset, so our findings cannot necessarily be generalised to these patient groups at this stage. Further clinical trials are on-going internationally, and we hope to include data from them in a future analysis to determine whether the promise of today’s results is confirmed in an even larger and more diverse group of patients.
Disclosures: None of the authors of this study has any conflict of interest to disclose.
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Vitamin D supplementation to prevent asthma exacerbations: a systematic review and meta-analysis of individual participant data
Published online: October 3, 2017
David A Jolliffe, Lauren Greenberg, Richard L Hooper, Christopher J Griffiths, Carlos A Camargo, Conor P Kerley, Megan E Jensen, David Mauger, Iwona Stelmach, Mitsuyoshi Urashima, Adrian R Martineau
The Lancet Respiratory Medicine
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