Reply to "Double-counting of effect sizes and inappropriate exclusion of studies in "The influence of vitamin D supplementation on IGF-1 levels in humans: A systematic review and meta_analysis"
View/ Open
Publisher version (Check access options)
Check access options
Date
2021Author
Kord-Varkaneh, HamedRinaldi, Giulia
Hekmatdoost, Azita
Fatahi, Somaye
Tan, Shing Cheng
Shadnoush, Mahdi
Khni, Vahid
Mousavi, Seyed Mohammad
Zarezadeh, Meysam
Salamat, Shekoufeh
Bawadi, Hiba
Rahmani, Jamal
...show more authors ...show less authors
Metadata
Show full item recordAbstract
Dear Editor,
We appreciate the comments provided to us in the letter from Amiri et al. We would like to offer some clarifications in response to the comments.
Firstly, the authors claimed that we included the control group more than once from the same publication including different arms. The authors also identified mistakes made during data screening and expressed concerns that the mistakes would lead to errors within our analysis (Kord-Varkaneh et al., 2020). We sincerely thank the authors for pointing out these mistakes. In response, based on The Cochrane Handbook for Systematic Reviews, we have now reanalyzed the results by combining the intervention groups to create a single pair-wise comparison and updated our meta-analysis as displayed below. We initially excluded Sorva, Antti et al. from our study because based on our inclusion criteria we only included studies that had more than 10 participants in each group (Sorva et al., 1994), although we did not originally include this criterion in our publication (Kord-Varkaneh et al., 2020). However, after including Norenstedt, S. et al. and Sinha-Hikim, I. et al. (Sinha-Hikim et al., 2015; Norenstedt et al., 2013) our overall effect size changed from (WMD: 4 ng/ml, 95 % CI: -4 to 11, p = 0.35) to (WMD: 1.01 ng/ml, 95 % CI: --6.78 to 8.81, p = 0.799) without a change in overall significance (Fig. 1). In addtion, subgroup analyses showed that vitamin D dosage ≤1000 IU/day (WMD: 11.36 ng/ml, 95 % CI: 1.57–21.16, I2 = 79 %) significantly increased IGF-1 than vitamin D dosage <1000 IU/day (WMD: -2.8 ng/ml, 95 % CI: -7.02 to 1.6, I2 = 51 %). Moreover, an intervention duration of ≤12 weeks (WMD: 9.92 ng/ml, 95 % CI: 3–16.83, I2 = 77 %) significantly increased IGF-1 compared to a duration of <12 weeks (WMD: -5.43 ng/ml, 95 % CI: -10.25 to -0.61, I2 = 0.0 %). In addition, baseline serum vitamin D (<20 ng/mL vas ≥20 ng/mL) we did not observe significantly.
Collections
- Human Nutrition [347 items ]
Related items
Showing items related by title, author, creator and subject.
-
25-Hydroxyvitamin D Concentrations and Clostridium difficile Infection: A Meta-Analysis
Furuya-Kanamori, L.; Wangdi, K.; Yakob, L.; McKenzie, S.J.; Doi, S.A.R.; Clark, J.; Paterson, D.L.; Riley, T.V.; Clements, A.C.A.... more authors ... less authors ( SAGE Publications Inc. , 2017 , Article)Background: Well-known risk factors for Clostridium difficile infection (CDI) are exposure to antibiotics and gastric acid suppressants. Recent studies have provided some evidence of an association between hypovitaminosis ... -
Association between Genetic Variants of GC Gene at 4q13.3 and Vitamin D Concentrations in Adult Females
sharif, Elham; Rizk, Nasser; Thakur, Hajera; Kurdi, Tasnim; Alwakeel, Mariam ( Longdom , 2019 , Article)Background: Vitamin D binding protein, encoded by the GC gene (on 4q13.3), plays an important role in transporting vitamin D. Several Genome-Wide Association Studies (GWASs) have established a significant association ... -
The impact of genetic and non-genetic factors on warfarin dose prediction in MENA region: A systematic review
Bader, Loulia Akram; Elewa, Hazem ( Public Library of Science , 2016 , Article Review)Background Warfarin is the most commonly used oral anticoagulant for the treatment and prevention of thromboembolic disorders. Pharmacogenomics studies have shown that variants in CYP2C9 and VKORC1 genes are strongly and ...