Yadav 2014.

Methods	Randomised, double‐blind, placebo‐controlled, parallel‐group trial Single‐centre, 6 months long Run‐in period: Not described, concomitant medication continued 18 were lost to follow‐up, reasons not provided Study analysed by intention‐to‐treat
Participants	Rohtak, India Indian N = 100. 49 m, 51 f. Mean age 9.6 yrs, range 5 to 13 yrs Inclusion criteria: Children aged between 3 and 14 yrs. With moderate to severe asthma as per Global Initiative for Asthma (GINA) guidelines, diagnosed by a physician. Exclusion criteria: Children on immunotherapy or anti‐IgE. History of premature birth (< 36 weeks). Home use of oxygen. Children with non‐wheezy asthma and clinical features of vitamin D deficiency (bony deformities and hypocalcaemic symptoms).
Interventions	Treatment (n = 50): oral vitamin D3 (cholecalciferol) 60,000 IU per month for 6 months. Control (n = 50): placebo powder in the form of glucose sachet. Vitamin D status not assessed
Outcomes	Primary outcome: Change in the level of asthma severity according to GINA guidelines. Secondary outcomes: Number of exacerbations during treatment period. Change in the PEFR. Change in steroid dosage. Level of control. Emergency visits.
Notes	No details on funding provided. Authors declare no conflict of interest
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of sequence generation not reported
Allocation concealment (selection bias)	Low risk	Allocation concealed in opaque envelopes
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind, placebo‐controlled trial
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind, placebo‐controlled trial
Incomplete outcome data (attrition bias) All outcomes	High risk	10/50 children in control arm and 8/50 in active arm were lost to follow‐up, but data for these 'lost' children are presented at the 6‐month time point (end of study)
Selective reporting (reporting bias)	Low risk	Nil to suggest selective reporting: outcomes listed in Methods are reported in Results. However, we did not have access to the trial protocol
Other bias	High risk	Marked change in classification of asthma severity between 6‐month time point and earlier time points suggests likelihood of misclassification bias operating at end‐study time point

25(OH)D, 25‐hydroxyvitamin D; ACT, Asthma Control Test; ASUI, Asthma Symptom Utility Index; ATAQ, Asthma Therapy Assessment Questionnaire; COPD, chronic obstructive pulmonary disease; FeNO, fractional exhaled nitric oxide concentration; FEV1, forced expiratory volume in one second; GFR, glomerular filtration rate; ICS, inhaled corticosteroids; IgE, immunoglobulin E; ITT, intention to treat; IU, international unit (40 IU vitamin D = 1 microgram vitamin D); PC20, provocative concentration of methacholine at which FEV1 decreased by 20%; PEFR, peak expiratory flow rate; SCRG, St George's Respiratory Questionnaire; SIT, specific immunotherapy; URTI, upper respiratory tract infection.