Table 1 Characteristics of included studies

Majak [ 16 ] 2009

● Randomized, double-blind, placebo-controlled

● 54 Patients sensitized only to house dust mites (HDM) as evidenced by a positive skin prick test.

● Intervention: Vitamin D3 Cholecalciferol, 1000 IU/week orally, single dose, for 1 year.

● Asthma symptoms measured at 3 and 12 months using a diary card (no validation of the diary card reported).

● Time frame: Sep 2005-April 2007

● The study included a third placebo arm that we considered not relevant for this systematic review.

Trial

● Age: 6–12 years (61% males)

● Control: No vitamin D3

● Funding: Medical University of Lodz, Poland

● Exclusion Criteria: FEV1 < 70%, any contraindication for SIT(Specific Immunotherapy), need for Budesonide (Inhaled Corticosteroid) dose of less than 400 mcg, or more than 800 mcg, any previous receiving of SIT, sensitization to allergens other than HDM, any discontinuation of SIT for any reason, maintenance dose of allergen extract not reached within 3 months of build-up phase of SIT, or missing more than one maintenance dose of allergen extract.

● Both arms received prednisone 20 mg For 3 month, and specific immunotherapy for 1 year.

● FEV1 at 3 and 12 month.

● Percentage reduction of median daily ICSs (Inhaled Corticosteroids) Dose at 3 and 12 months.

● Serum 25 hydroxyvitamin D3 levels (ng/ml) at 3 months.

● Mean serum 25 hydroxyvitamin D levels at baseline: 31.3 (SD: 3.4), 32.0 (SD: 3.1), for control and intervention groups, accordingly.

● Setting: Allergy clinic in Poland.

Lewis [ 18 ] 2012

● Pilot study. Randomized Controlled Trial

● 30 Patients diagnosed with chronic persistent asthma and on current daily controller asthma medication; all nonwhite.

● Intervention: vitamin D3 (Cholecalciferol) 1,000 IU, daily for 1 year.

● Asthma Control Test scores (ACT) (validated score [19]) at 6 month and 12 month.

● Time frame: 1 year.

● Control: Placebo.

● Funding: LB595

● Age: 6-17 years

● FEV1 at 6 month and 12 month

State of Nebraska Tobacco Settlement

● Mean Asthma Control Test (ACT) Score at baseline was 17.8.

● Serum 25 hydroxyvitamin D3 levels (ng/ml) at 6 month and 12 month

Funds.

● Baseline vitamin D levels not reported

● Setting: Creighton University Medical Center.

Parameters were assessed at baseline in the winter, at 6 months later in the summer, and at 12 months later during the next winter.

Schou [ 14 ] 2003

Randomized, double-blind, two-period crossover trial.

● 17 Patients: (14 boys)

● Intervention: Vitamin D3 (cholecalciferol) 15 μg (600 IU), vitamin A 1.5 mg, thiamine 3 mg, riboflavin 3 mg, nicotinamid 20 mg, ascorbic acid 75 mg, pyridoxine 2 mg, and panthotenic acid 8 mg, once daily in the morning, for four weeks.

● Asthma symptoms score (Developed by investigator; no validation of the score reported) at 4 weeks.

● Time frame: November-January (year not specified).

● Age: 6-14 years.

● Mean height: 144.4 (104.8–176.2) cm

Funding: Not reported.

● Mean weight 38.8(16.8–72.6) kg

● Run-in and

● Pre pubertal: 12 boys and 2 girls.

washout periods of 2 weeks and treatment periods of 4 weeks’ duration.

● Treated with inhaled corticosteroid for at least one year before entering the study.

● FEV1 at 4 weeks.

● Use of Beta 2 agoinsts (Puffs/day) at 4 weeks.

● Baseline vitamin D levels not reported

● Control: Placebo.

● Serum 25 hydroxyvitamin D3 levels (ng/ml), mean level.

● Setting: Outpatient Children’s Clinic, in Randers, Denmark.

● Both arms received inhaled dry-powder budesonide 400 μg, daily, for four weeks.

Majak [ 17 ] 2011

● Randomized, double-blind, parallel-group trial.

● 48 Patients with newly diagnosed asthma and sensitive only to house dust mites

● Intervention: vitamin D3(cholecalciferol)500 IU.Dosage details not described.

● Asthma Therapy Assessment Questionnaire (ATAQ) every month up to six month (validated score [20]).

● Time frame: 6 months.

● Funding: Medical University of Lodz, Poland.

● Mean age: 11.5 (5-18) years.

● Newly diagnosed asthma, sensitive only to House Dust Mite (HDM).

● Control: placebo.

● Both arms received budesonide 800 mg/d administered as a dry powder for six month.

● FEV1, mean of monthly measures

● Serum 25 hydroxyvitamin D3 levels (ng/ml), mean of a monthly measures.

● Number of Children with Asthma Exacerbations.

● Exclusion criteria included treatment with an oral, inhaled, or intranasal corticosteroid and supplementation with vitamin D during 6 months preceeding the trial, history of fractures in the last 2 years, immunotherapy, obesity (BMI > 30 Kg/m^2), and other chronic diseases.

● Mean serum 25 hydroxyvitamin D levels at baseline 35.1 (SD:16.9), 36.1

(SD:13.9), for control and intervention groups, accordingly.

● Setting: Allergy clinic in Poland.