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©The Author(s) 2022.
World J Methodol. May 20, 2022; 12(3): 164-178
Published online May 20, 2022. doi: 10.5662/wjm.v12.i3.164
Published online May 20, 2022. doi: 10.5662/wjm.v12.i3.164
Table 1 Salient features of the reviewed trials
Ref. | Design | Participants | Interventions | Outcomes |
Jamilian et al[37], 2016 | Randomized, double-blind, placebo-controlled clinical trial; Intervention arms: Two; Single-centered trialTrial duration: 6 wk. Trial conducted in: Iran; Obtained ethical clearance and participant consent. Funding information provided. Clinical trial registration number: IRCT201509115623N52 | Participants diagnosed with GDM (used ADA criteria); 60 participants randomized into different treatment arms (vitamin D3 and evening primrose oil: n = 30, placebo: n = 30); Mean age of participants: -Vitamin D3 and evening primrose oil receiving group: 28.4 ± 6.2 yr; -Placebo receiving group: 29.6 ± 4.3 yr | Two intervention arms: (1) 1000 IU of vitamin D and 1000 mg of evening primrose oil daily for 6 wk; and (2) Placebo | Attrition from vitamin D supplemented arm: n = 3; Other outcomes reported: Fasting plasma glucose |
Jamilian et al[17], 2017 | Randomized, double blinded, placebo-controlled clinical trial; Intervention arms: four; Single centered trial; Trial duration: 6 wk. Trial conducted in: Iran; Obtained ethical clearance and participant consent. Funding information provided. Clinical trial registration number: IRCT201605135623N78 | Participants diagnosed with GDM (used ADA criteria); 140 participants randomized into different treatment arms (vitamin D and omega-3 fatty acid receiving group: n = 35, vitamin D receiving arm: n = 35, omeag-3 fatty acid receiving arm: n = 35, placebo receiving arm: n = 35); Mean age of participants: -Vitamin D and omega-3 fatty acid receiving group: 31.2 ± 4.3 yr; -Vitamin D receiving group: 31.5 ± 7.0 yr; -Omega-3 receiving group: 30.7 ± 3.5 yr; -Placebo receiving group: 30.7 ± 4.1 yr | Four intervention arms: (1) Vitamin D and omega-3 fatty acid: 50000 IU of vitamin D two weekly and 1000 mg omega-3 fatty acid twice daily; (2) Vitamin D: 50000 IU vitamin D every 2 wk; (3) Omega-3 fatty acid: 1000 mg omega-3 fatty acids two times a day; and (4) Placebo | No attrition from vitamin D supplemented arm; Other outcomes reported: Fasting plasma glucose |
Jamilian et al[33], 2019a | Randomized, double-blind, placebo-controlled; Intervention arms: 3; Trial conducted in: Iran; Single centered trial; Trial duration: 6 wk; Obtained ethical clearance and participant consent. Funding information provided. Trial ID: IRCT201706075623N119 | Participants diagnosed with GDM (used ADA criteria); 90 participants randomized into different treatment arms (probiotic arm: n = 30, vitamin D and probiotic arm: n = 30, placebo arm: n = 30); Mean age of participants: -Probiotic arm: 31.2 ± 5.9 yr; -Vitamin D and probiotic arm: 28.9 ± 6.1 yr; -Placebo arm: 29.9 ± 3.7 yr | Three intervention arms: (1) Probiotic: 8 × 109 CFU/g; (2) Vitamin D3 (50,000 IU) every 2 wk plus 8 × 109 CFU/g probiotic; Placebo | No attrition from vitamin D supplemented arm; Other outcomes reported: (1) Newborn hyperbilirubinemia; (2) Newborn hospitalization; (3) Macrosomia; and (4) Cesarean section. Fasting plasma glucose |
Jamilian et al[36], 2019b | Randomized, double-blind, placebo-controlled. Intervention arms: 2; Trial conducted in: IranSingle centered trialTrial duration: 6 wkObtained ethical clearance and participant consent. Funding information provided.Trial ID: IRCT201704225623N109 | Participants diagnosed with GDM (used ADA criteria); 60 participants randomized into different treatment arms (vitamin D-magnesium-zinc-calcium arm: n = 30, placebo arm: n = 30). Mean age of participants: -Vitamin D-magnesium-zinc-calcium arm: 27.7 ± 4.0 yr; -Placebo arm: 29.1 ± 4.1 yr | Two intervention arms: (1) Vitamin D (200 IU) along with 100 mg magnesium, 4 mg zinc, 400 mg calcium twice daily; and (2) Placebo | No attrition from vitamin D supplemented armOther outcomes reported: (1) Newborn hyperbilirubinemia; (2) Newborn hospitalization; (3) Macrosomia; and (4) Cesarean section. Fasting plasma glucose |
Asemi et al[31], 2014a | Randomized, double-blind, placebo-controlled trial. Intervention arms: 2; Trial conducted in: Iran; Single centered trial; Trial duration: 6 wk; Obtained ethical clearance and participant consent. Funding information provided.Trial ID: IRCT201305115623N7 | Participants diagnosed with GDM (used ADA criteria); 50 participants randomized into different treatment arms (vitamin D arm: n = 25, placebo arm: n = 25). Mean age of participants: -Vitamin D arm: 31.1 ± 5.5 yr; -Placebo arm: 30.8 ± 6.2 yr | Two intervention arms: (1) Vitamin D: 50,000 IU vitamin D3 pearl two times during the trial period (at baseline and day 21); and (2) Placebo | Attrition from vitamin D supplemented arm: n = 3; Other outcomes reported: (1) Newborn hyperbilirubinemia; (2) Newborn hospitalization; (3) Macrosomia; and (4) Cesarean section |
Asemi et al[16], 2014b | Randomized, placebo-controlled clinical trial. Intervention arms: TwoMulti-centric trial. Trial duration: 6 wk. Trial conducted in: IranObtained ethical clearance and participant consent. Funding information provided. Clinical trial registration number: IRCT201311205623N11 | Participants diagnosed with GDM (used ADA criteria); 56 participants randomized into different treatment arms (vitamin D and calcium: n = 28, placebo receiving group: n = 28). Mean age of participants: -Vitamin D and calcium receiving arm: 28.7 ± 6.0 yr; -Placebo receiving arm: 30.8 ± 6.6 yr | Two intervention arms: (1) 1000 mg calcium carbonate daily and 50000 U vitamin D3 at the baseline and day 21 of the study; and (2) Placebo | Attrition from vitamin D supplemented arm: n = 3. Other outcomes reported: Fasting plasma glucose |
Karamali et al[32], 2016 | Randomized, double-blind, placebo-controlled trial; Intervention arms: 2; Trial conducted in: Iran; Multicentric trialTrial duration: 6 wk; Obtained ethical clearance and participant consent. Funding information provided. Trial ID: IRCT201407115623N23 | Participants diagnosed with GDM (used ADA criteria); 60 participants randomized into different treatment arms (vitamin D and calcium arm: n = 30; placebo arm: n = 30). Mean age of participants: -Vitamin D and calcium arm: 28·7 ± 6·1 yr; -Placebo arm: 31·6 ± 6·3 yr | Two intervention arms: (1) Vitamin D3 (50000 IU) at baseline and day 21 along with 1000 mg calcium carbonate daily; and (2) Placebo | No attrition from vitamin D supplemented arm; Other outcomes reported: (1) Newborn hyperbilirubinemia; (2) Newborn hospitalization; (3) Macrosomia; and (4) Cesarean section |
Karamali et al[14], 2018 | Randomized, double-blind, placebo-controlled trial; Intervention arms: 2; Single centered trial. Trial duration: 6 wk; Trial conducted in: Iran; Obtained ethical clearance (participant consent information unclear). Funding information provided. Trial registration details: Unclear | Participants diagnosed with GDM (used ADA criteria); 60 participants randomized into different treatment arms; (Magnesium, zinc, calcium and vitamin D supplements arm: n = 30; Placebo arm: n = 30); Mean age of participants: -Magnesium, zinc, calcium and vitamin D: 30.0 ± 4.5 yr; -Placebo arm: 31.1 ± 4.2 yr | Two intervention arms: (1) 100 mg magnesium, 4 mg zinc, 400 mg calcium and 200 IU vitamin D two times a day for 6 wk; and (2) Placebo | No attrition from vitamin D supplemented arm; Other outcomes reported: Fasting plasma glucose |
Razavi et al[35], 2017 | Randomized, double-blind, placebo-controlled, Intervention arms: 4; Trial conducted in: Iran. Single centered trial. Trial duration: 6 wk; Obtained ethical clearance and participant consent. Funding information provided. Trial ID: IRCT201701305623N106 | Participants diagnosed with GDM (used ADA criteria); 120 participants randomized into different treatment arms (vitamin D and omega-3 arm: n = 30; omega-3 arm: n = 30; vitamin D arm: n = 30; placebo: n = 30); Mean age of participants: -Vitamin D and omega-3 arm: 29.9 ± 4.0 yr; -Omega-3 arm: 29.7 ± 3.6 yr; -Vitamin D arm: 29.9 ± 5.0 yr; -Placebo: 29.2 ± 3.4 yr | Four intervention arms: (1) Vitamin D (50000 IU): Two weekly two times a day; (2) Vitamin D (50000 IU) two weekly plus 1000 mg omega-3 fatty acids two times a day; (3) 1000 mg omega-3 fatty acids two times a day; and (4) Placebo | No attrition from vitamin D supplemented arm; Other outcomes reported: (1) Newborn hyperbilirubinemia; (2) Newborn hospitalization; (3) Macrosomia; and (4) Cesarean section |
Valizadeh et al[34], 2016 | Randomized controlled trial. Investigators and patients were not blinded. Intervention arms: 2; Single centered trial; Trial conducted in: Iran; Trial duration: Until delivery; Obtained ethical clearance and participant consent. Funding information provided. Trial ID: IRCT2012101611144N1 | Participants diagnosed with GDM (used ADA criteria); 96 participants randomized into different treatment arms (vitamin D arm: n = 48; no supplement arm: n = 48); Mean age of participants: -Vitamin D arm: 32.0 ± 5.5 yr; -No supplement arm: 32.4 ± 4.7 yr | Two intervention arms: (1) 700000 IU vitamin D3 in total (regimen differed by gestational age of GDM patients); and (2) Comparison group did not receive any supplementation | Attrition from vitamin D supplemented arm: n = 4; Other outcomes reported: (1) Newborn hyperbilirubinemia; (2) Macrosomia; (3) Cesarean section; and (4) Fasting plasma glucose |
Yazdchi et al[15], 2016 | Randomized, double-blinded placebo-controlled clinical trial; Intervention arms: 2; Multi-center trial; Trial duration: 8 wk. Trial conducted in: Iran; Obtained ethical clearance and participant consent. Funding information provided. Clinical trial registration number: IRCT201306253140N11 | Participants diagnosed with GDM (used International Association of Diabetes and Pregnancy Study Groups criteria); 76 participants randomized into different treatment arms: Vitamin D arm: n = 38; placebo arm: n = 38; Mean age of participants: -Vitamin D arm: 31.64 ± 4.40 yr; -Placebo arm: 32.11 ± 3.61 yr | Two intervention arms:(1) 50000 IU vitamin D3 oral capsules two weekly for 8 wk; and (2) Placebo | Attrition from vitamin D supplemented arm: n = 4; Other outcomes reported: Fasting plasma glucose |
Zhang et al[38], 2016 | Randomized, double-blind, placebo-controlled trial. Intervention arms: 4; Single centered trial. Trial duration: 24-28 wk of pregnancy to delivery; Trial conducted in: China; Obtained ethical clearance and participant consent. Funding information provided. Clinical trial registration details: Unclear | Participants diagnosed with GDM (criteria unclear). 133 participants randomized into different treatment arms (low dose vitamin D: n = 38; medium dose vitamin D: n = 38; high dose vitamin D: n = 37; placebo: n = 23); Mean age of participants: -Placebo arm: 29.8 ± 4.7; -Low dose vitamin D arm: 30.3 ± 5.1; -Medium dose vitamin D arm: 29.4 ± 4.9; -High dose vitamin D arm: 30.1 ± 4.5 | Four intervention arms: (1) Low dose vitamin D: 200 IU daily; (2) Medium dose vitamin D: 2000 IU monthly; and (3) High dose vitamin D: 50000 IU every 2 wk. Placebo | Attrition from vitamin D supplemented arm: n = 4 |
Li and Xing[13], 2016 | Randomized, double-blinded clinical trial. Intervention arms: 2. Multi-centric trial. Trial duration: 16 wk. Trial conducted in: China; Obtained ethical clearance and participant consent. Funding information provided. Clinical trial registration details: Unclear | Participants diagnosed with GDM (used ADA criteria)103 participants randomized into different treatment arms (yoghurt with vitamin D: n = 52, plain yoghurt: n = 51); Mean age of participants: -Yoghurt supplemented with vitamin D receiving arm: 29.0 ± 5.3 yr; -Plain yoghurt arm: 28.3 ± 4.1 yr | Two intervention arms: (1) Yoghurt was supplemented with 500 IU of vitamin D3 twice daily for 16 wk; and (2) plain yoghurt: Twice daily for 16 wk | Attrition from vitamin D supplemented arm: n = 4. Other outcomes reported: Fasting plasma glucose |
Table 2 Risk of bias assessment of respective trial included in the review[23]
Ref. | Random sequence generation (selection bias) | Allocation concealment (selection bias) | Blinding of participants and personnel (performance bias); All outcomes | Blinding of outcome assessment (detection bias); All outcomes | Incomplete outcome data (attrition bias); All outcomes | Selective reporting (reporting bias) | Other bias |
Jamilian et al[37], 2016 | Low | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Low | Low | Low | Low |
Jamilian et al[17], 2017 | Low | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Unclear | Low | Low | Low |
Jamilian et al[33], 2019a | Low risk | Unclear risk; Comment: Precise mechanism unclear | Low risk | Low risk | Low risk | Low risk | Low risk |
Jamilian et al[36], 2019b | Low risk | Unclear risk; Comment: Precise mechanism unclear | Low risk | Low risk | Low risk | Low risk | Low risk |
Asemi et al[31], 2014a | Low risk | Unclear risk; Comment: Precise mechanism unclear | Low risk | Low risk | Low risk | Low risk | Low risk |
Asemi et al[16], 2014b | Low | Low | Low | Low | Low | Low | Low |
Karamali et al[32], 2016 | Low risk | Unclear risk; Comment: Precise mechanism unclear | Low risk | Low risk | Low risk | Low risk | Low risk |
Karamali et al[14], 2018 | Low | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Low | Low | Low | Low |
Razavi et al[35], 2017 | Low risk | Unclear risk; Comment: It’s unclear if the bottles were sequentially numbered and identical in appearance | Low risk | Low risk | Low risk | Low risk | Low risk |
Valizadeh et al[34], 2016 | Low risk | Unclear risk | High risk; Comment: Both investigators and participants were not blinded | Low risk | Low risk | Low risk | |
Yazdchi et al[15], 2016 | Low | Unclear | Unclear | Low | Low | Low | Low |
Zhang et al[38], 2016 | Low | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Low | Low | Low |
Li and Xing[13], 2016 | Low | Unclear; Comment: Precise mechanism unclear | Unclear; Comment: Precise mechanism unclear | Low | Low | Low | Low |
Table 3 League table. Outcomes: cesarean section (left lower triangle) and newborn hyperbilirubinemia (right upper triangle). Interventions of interest: represented in diagonal cells
Interventions and effect sizes | |||||||
Vitamin D and probiotic | 1.14 (0.22, 5.92)1 | 0.79 (0.19, 3.27) | 0.59 (0.16, 2.20) | 0.73 (0.18, 2.96) | 0.28 (0.09, 0.91)2 | 0.34 (0.09, 1.32) | 0.42 (0.10, 1.69) |
0.76 (0.27, 2.19) | Vitamin D and omega-3 fatty acid | 0.70 (0.17, 2.79) | 0.52 (0.16, 1.75) | 0.64 (0.14, 2.99) | 0.25 (0.08, 0.77) | 0.30 (0.09, 0.98) | 0.37 (0.09, 1.44) |
1.48 (0.52, 4.21) | 1.94 (0.71, 5.28) | Vitamin D and calcium | 0.75 (0.29, 1.96) | 0.91 (0.25, 3.35) | 0.35 (0.16, 0.77) | 0.43 (0.16, 1.19) | 0.53 (0.18, 1.55) |
0.69 (0.29, 1.68) | 0.91 (0.44, 1.90) | 0.47 (0.21, 1.07) | Vitamin D | 1.22 (0.37, 3.96) | 0.47 (0.27, 0.83) | 0.57 (0.27, 1.22) | 0.71 (0.28, 1.78) |
0.68 (0.30, 1.54) | 0.89 (0.34, 2.35) | 0.46 (0.17, 1.20) | 0.97 (0.45, 2.13) | Probiotic | 0.39 (0.14, 1.09) | 0.47 (0.14, 1.60) | 0.58 (0.16, 2.07) |
0.54 (0.25, 1.18) | 0.71 (0.35, 1.46) | 0.37 (0.18, 0.74) | 0.78 (0.52, 1.19) | 0.80 (0.42, 1.56) | Placebo | 1.22 (0.64, 2.33) | 1.50 (0.72, 3.14) |
0.68 (0.24, 1.90) | 0.89 (0.40, 1.99) | 0.46 (0.17, 1.22) | 0.98 (0.49, 1.96) | 1.00 (0.39, 2.58) | 1.24 (0.63, 2.45) | Omega-3 fatty acid | 1.23 (0.46, 3.28) |
1.23 (0.33, 4.57) | 1.61 (0.45, 5.79) | 0.83 (0.23, 2.97) | 1.76 (0.56, 5.53) | 1.81 (0.52, 6.33) | 2.25 (0.78, 6.52) | 1.81 (0.51, 6.37) | Magnesium, zinc, calcium, and vitamin D |
Table 4 League table: Outcomes: Macrosomia (left lower triangle) and newborn hospitalization (right upper triangle). Interventions of interest: Represented in diagonal cells
Interventions and effect sizes | |||||||
Vitamin D and probiotic | 1.27 (0.24, 6.66)1 | 0.88 (0.21, 3.69) | 0.66 (0.18, 2.49) | 0.97 (0.21, 4.41) | 0.31 (0.09, 1.03) | 0.38 (0.10, 1.49) | 0.47 (0.11, 1.91) |
0.94 (0.11, 8.45) | Vitamin D and omega-3 fatty acid | 0.70 (0.17, 2.79) | 0.52 (0.16, 1.75) | 0.76 (0.15, 4.02) | 0.25 (0.08, 0.77)2 | 0.30 (0.09, 0.98) | 0.37 (0.09, 1.44) |
3.36 (0.13, 88.67) | 3.56 (0.14, 93.17) | Vitamin D and calcium | 0.75 (0.29, 1.96) | 1.10 (0.26, 4.59) | 0.35 (0.16, 0.77) | 0.43 (0.16, 1.19) | 0.53 (0.18, 1.55) |
0.98 (0.13, 7.29) | 1.03 (0.18, 6.09) | 0.29 (0.01, 6.77) | Vitamin D | 1.46 (0.39, 5.50) | 0.47 (0.27, 0.83) | 0.57 (0.27, 1.22) | 0.71 (0.28, 1.78) |
1.93 (0.19, 20.18) | 2.05 (0.15, 27.32) | 0.58 (0.02, 20.11) | 1.98 (0.17, 22.68) | Probiotic | 0.32 (0.10, 1.07) | 0.39 (0.10, 1.53) | 0.48 (0.12, 1.97) |
0.37 (0.08, 1.77) | 0.40 (0.08, 1.85) | 0.11 (0.01, 1.98) | 0.38 (0.11, 1.36) | 0.19 (0.02, 1.55) | Placebo | 1.22 (0.64, 2.33) | 1.50 (0.72, 3.14) |
0.63 (0.08, 4.84) | 0.67 (0.12, 3.71) | 0.19 (0.01, 4.45) | 0.64 (0.13, 3.13) | 0.33 (0.03, 3.83) | 1.69 (0.45, 6.30) | Omega-3 fatty acid | 1.23 (0.46, 3.28) |
1.87 (0.14, 25.22) | 1.98 (0.15, 26.45) | 0.56 (0.02, 19.45) | 1.91 (0.17, 21.96) | 0.97 (0.05, 18.42) | 5.00 (0.62, 40.28) | 2.96 (0.25, 34.96) | Magnesium, zinc, calcium, and vitamin D |
Table 5 The surface under the cumulative ranking curve values. Outcomes: Newborn hyperbilirubinemia, newborn hospitalization, and cesarean section
Intervention | Outcomes | |||||
Newborn hyperbilirubinemia | Newborn hospitalization | Cesarean section | ||||
SUCRA | Mean rank | SUCRA | Mean rank | SUCRA | Mean Rank | |
Vitamin D and omega-3 fatty acid | 81.8 | 2.31 | 81.1 | 2.31 | 46.4 | 4.8 |
Vitamin D and probiotic | 76.2 | 2.7 | 70.7 | 3.0 | 66.3 | 3.4 |
Probiotic | 62.2 | 3.6 | 69.5 | 3.1 | 36.6 | 5.4 |
Vitamin D and calcium | 67.9 | 3.3 | 67.2 | 3.3 | 87.6 | 1.91 |
Vitamin D | 52.8 | 4.3 | 52.4 | 4.3 | 39.0 | 5.3 |
Magnesium, zinc, calcium, and vitamin D | 32.4 | 5.7 | 32.2 | 5.7 | 73.8 | 2.8 |
- Citation: Saha S, Saha S. Participant attrition and perinatal outcomes in prenatal vitamin D-supplemented gestational diabetes mellitus patients in Asia: A meta-analysis. World J Methodol 2022; 12(3): 164-178
- URL: https://www.wjgnet.com/2222-0682/full/v12/i3/164.htm
- DOI: https://dx.doi.org/10.5662/wjm.v12.i3.164