1. Vitamin D supplementation to prevent asthma exacerbations: a systematic review and meta-analysis of individual participant data 
David A Jolliffe, PhD, Lauren Greenberg, MSc, Richard L Hooper, PhD, Prof Christopher J Griffiths, DPhil, Prof Carlos A Camargo, MD, Conor P Kerley, PhD, Megan E Jensen, PhD, Prof David Mauger, PhD, Prof Iwona Stelmach, PhD, Prof Mitsuyoshi Urashima, MD, Prof Adrian R Martineau, PhD 
The Lancet Respiratory Medicine 
Volume 5, Issue 11, Pages (November 2017)
DOI: /S (17)
Copyright © 2017 Elsevier Ltd Terms and Conditions

2. Figure 1 Study selection
The Lancet Respiratory Medicine 2017 5, DOI: ( /S (17) )
Copyright © 2017 Elsevier Ltd Terms and Conditions

3. Figure 2
Two-step individual participant data meta-analysis, event rate for asthma exacerbations requiring treatment with systemic corticosteroids
Weights are from the random-effects analysis. No asthma exacerbations requiring treatment with systemic corticosteroids arose in the trials by Urashima and colleagues9 and Majak and colleagues.10 Only one such event arose in the trial by Tachimoto and colleagues;14 as such, an adjusted incidence rate ratio could not be calculated for this study.
The Lancet Respiratory Medicine 2017 5, DOI: ( /S (17) )
Copyright © 2017 Elsevier Ltd Terms and Conditions

4. Figure 3
Effects of vitamin D supplementation on asthma exacerbation rate by baseline circulating 25(OH)D concentration categorised by 25 nmol/L strata
Shown are the results of one-step individual participant data meta-analysis. The incidence rate ratio is adjusted for age and sex. Mean and 95% CI are presented. 25(OH)D=25-hydroxyvitamin D.
The Lancet Respiratory Medicine 2017 5, DOI: ( /S (17) )
Copyright © 2017 Elsevier Ltd Terms and Conditions