Table 1

Baseline characteristics by allocation

Vitamin D3 (n=125)*Placebo (n=125)*
Age, years49.4 (14.8)46.4 (13.8)
Sex
 Male, n (%)55 (44%)54 (43%)
 Female, n (%)70 (56%)71 (57%)
Ethnicity
 White, n (%)103 (82%)99 (79%)
 Black/Black British, n (%)10 (8%)12 (10%)
 Other, n (%)12 (10%)14 (11%)
Body mass index ≥30 kg/m236 (29%)29 (23%)
Current smoker, n (%)8 (6%)9 (7%)
BTS step of treatment at enrolment
 2: Regular preventer therapy58 (46%)56 (45%)
 3: Initial add-on therapy49 (39%)54 (43%)
 4: Persistent poor control17 (14%)15 (12%)
 5: Continuous/frequent use of OCS1 (1%)0 (0%)
Medication use
 ICS dose at entry in betamethasone equivalents,† μg668 (559)783 (693)
 Inhaled LABA use,‡ n (%)63 (50%)67 (54%)
 Leukotriene antagonist use, n (%)15 (12%)14 (11%)
Vaccine uptake
 Influenza vaccine, n (%)106 (85%)109 (87%)
 Pneumococcal vaccine, n (%)50 (40%)31 (25%)
Median no. of URI/exacerbations requiring OCS or increase in ICS in previous 12 months (IQR)2.0 (1.0 to 3.0)2.0 (1.0 to 3.0)
Median no. of days since last exacerbation/URI requiring OCS or increase in ICS (IQR)122 (69 to 237)132 (75 to 248)
Median asthma duration, years (IQR)25 (14 to 36)23 (14 to 32)
Managed exclusively in primary care, n (%)110 (88%)111 (89%)
ACT score (SD)19.2 (3.9)18.9 (3.9)
Median SGRQ score (IQR)23.7 (14.4 to 37.4)20.7 (11.1 to 35.3)
Eczema, n (%)54 (43%)48 (38%)
Allergic rhinitis, n (%)89 (71%)95 (76%)
Peripheral blood eosinophil count ×109/L0.28 (0.22)0.29 (0.23)
Peripheral blood eosinophil count >0.5×109/L, n (%)11 (9%)10 (8%)
Prebronchodilator FEV1, % predicted82.0 (18.7)81.0 (20.4)
Morning PEFR during run-in period, L/min383 (106)379 (123)
FENO, ppb38.1 (29.1)37.0 (26.0)
Vitamin D status
 Serum 25(OH)D concentration, nmol/L49.8 (25.2)49.4 (24.2)
 Serum 25(OH)D <75 nmol/L105 (84%)101 (81%)
 Serum 25(OH)D <50 nmol/L72 (58%)72 (58%)
 Serum 25(OH)D <25 nmol/L, n (%)19 (15%)17 (14%)
Randomised to induced sputum substudy24 (19%)26 (21%)
  • *Mean (SD) presented unless stated otherwise.

  • †1 μg betamethasone assumed equivalent to 1 μg budesonide, 0.5 mcg fluticasone dipropionate and 0.75 mcg ciclesonide.

  • ‡Includes combinations of ICS/LABA and LABA.

  • 25(OH)D, 25-hydroxyvitamin D; ACT, asthma control test; BTS, British Thoracic Society guidelines; ICS, inhaled corticosteroids; LABA, long-acting β-2 agonist; OCS, oral corticosteroids; PEFR, peak expiratory flow rate; ppb, parts per billion; SGRQ, St George's Respiratory Questionnaire; URI, upper respiratory infection.