Table 3.

Included studies for curative effect and safety of vitamin D intake

Authors	Publication Country year	Country	Design	Controls	Number	Vitamin D dose	Curative effect	Safety	Jadad scores	References
Zendedel et al	2015	Iran	Single-center, double-blind, Placebo and randomized	Placebo	44 vs 44	Oral doses of 100,000 IU per month for 6 months	Decreased COPD exacerbation and improved FEV1in the patients with severe COPD	NA	3	41
Martineau et al	2015	UK	Multicenter, double-blind, and randomized	Placebo	118 vs 122	Six bimonthly oral doses of 120,000 IU	Effective against moderate or severe exacerbation in COPD patients with 25(OH)D deficiency	No serious adverse event	5	38
Bjerk et al	2013	USA	Single center and pilot randomized	Placebo	18 vs 18	Oral doses of 2,000 IU daily for 6 weeks	No discernible effect on a simple measure of physical performance	NA	1	40
Hornikx et al	2012	Belgium	Double-blind and randomized	Placebo	25 vs 25	A monthly dose of 100,000 IU for 1 year	Improvement in inspiratory muscle strength and maximal oxygen uptake	NA	4	39
Lehouck et al	2012	Belgium	Randomized	Placebo	91 vs 91	A monthly dose of 100,000 IU for 1 year	Reduced exacerbation in COPD patients with 25(OH)D deficiency	Four with mild and asymptomatic hypercalcemia	4	9

Abbreviations: 25(OH)D, 25-hydroxyvitamin D; FEV₁, forced expiratory volume in 1 second; NA, not applicable.