Table 2 Characteristics of the included case–control studies
From: Vitamin D deficiency in patients with cystic fibrosis: a systematic review and meta-analysis
First author | Year | Country | Study population | Sex | Multivitamins | Received vitamin D supplements | Age of cases | Age of controls | n case | Levels of vitamin D in cases (ng/ml) (sd) | n control | Levels of vitamin D in controls (ng/ml) (sd) | 25OHD assay | Season adjust | Season matching | Season of measurement | QA |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Ambroszkiewicz et al. [23] | 2013 | Poland | CF | Both | All CF children, except for 2, were pancreatic insufficient and were routinely supplemented with vitamin D3 (400 IU/day) | All or some received vitamin D supplements | 7 ± 1 | 7 ± 1 | 35 | 19/94 ± 7.78 | 35 | 24/85 ± 8.21 | Chemiluminescence immunoassay using kits from DiaSorin (USA) | NO | NR | – | 6 |
Buntain et al. [24] | 2004 | Australia | CF | Both | Supplemental vitamin D in the form of a multivitamin was taken by 116 CF individuals in a mean (SD) daily dose of 4.9 (1.4) mg/day (194.7 (54.8) IU/day) | – | CHILDRENAND ADOL | Range: 5.6–48.3 | 95 | 24/3 ± 16.3 | 107 | 26 ± 16.3 | DiaSorin RIA double antibody assay (DiaSorin, Stillwater, Minnesota, USA) | NO | NR | All 4 seasons | 6 |
ADULTS | 5.6–48.3 | 58 | 21/9 ± 20 | 42 | 23/8 ± 20.49 | DiaSorin RIA double antibody assay (DiaSorin, Stillwater, Minnesota, USA) | NO | NR | All 4 seasons | 7 | |||||||
Greer et al. [25] | 2003 | Australia | CF | Both | – | – | 8.51 ± 1.84 | 8.70 ± 1.50 | 87 | 25/7 ± 6.22 | 92 | 26/44 ± 6.1 | DiaSorin RIA Double Antibody assay | NO | NR | – | 7 |
13.62 ± 2.2 | 13.49 ± 1.94 | 87 | 23/68 ± 6.5 | 92 | 25/7 ± 6.67 | DiaSorin RIA Double Antibody assay | NO | NR | – | 6 | |||||||
27.00 ± 7.56 | 26.66 ± 7.49 | 62 | 22/11 ± 7.95 | 50 | 23/8 ± 7.54 | DiaSorin RIA Double Antibody assay | NO | NR | – | 6 | |||||||
Solomons et al. [28] | 1981 | USA | CF | Both | 15 of 18 patients were taking supplemental vitamin D | All or some received vitamin D supplements | 11 ± 3 | 13 ± 1.75 | 18 | 17/4 ± 8 | 18 | 23/8 ± 5.6 | Competitive binding method of Haddad and Chyu (Haddad J, Chyu Ki. Competitive protein binding radioassay for 25-hydroxy-cholecalciferol. J Chin Endocrunol 197 l;33:992–5.) | YES | YES | – | 6 |
Jakovska et al. [26] | 2018 | Macedonia | stable CF children | – | – | – | 8.25 ± 1.9 | 7.5 ± 1.9 | 35 | 23/8 ± 10.9 | 21 | 25/6 ± 11.5 | Electrohemiluminiscent method | NO | NR | – | 7 |
Stead et al. [29] | 1988 | London | CF | Both | The mean daily intake of vitamin D was 19 1 jg (764 IU), range 0 6–54 3 pg (24–2172 IU). Only seven of the 31 patients were not taking supplements of vitamin D | All or some received vitamin D supplements | 25/5 | 24. 5 | 28 | 10/4 ± 6.1 | 28 | 14 ± 4 | Serum 25(OH)D concentration was measured by the method of Preece et al., and serum 1,25-dihydroxycholecalciferol (1,25(OH)2D) concentration by a radioreceptor assay | NO | NR | Automn | 7 |
Thursfield et al. [30] | 2018 | London | CF | Both | 91%(102) of CF subjects being prescribed fat-soluble vitamin supplements | All or some received vitamin D supplements | 7.8 ± 4.3 | 12.4 ± 1.22 | 113 | 22/8 ± 15.56 | 6 | 22/8 ± 12.58 | Mass spectrometry coupled with high-performance liquid chromatography | NO | NR | winter (October to March inclusive) versus summer (April to September inclusive) | 7 |
Jakovska-Maretti et al. [27] | 2013 | Macedonia | stable CF patients | – | – | – | 8.5 ± 2.4 | Age-match controls | 23 | 25/56 ± 12.1 | 70 | 27/75 ± 2.1 | ELISA assays | NO | NR | – | 7 |
15 ± 2.4 | 23 | 22/07 ± 10 | 29/4 ± 8.3 | ||||||||||||||
25 ± 2.7 | 24 | 20/4 ± 8.4 | 22/78 ± 7.84 |