Association of Serum Vitamin D Levels with Level of Control of Childhood Asthma

The serum level of vitamin D and prevalence of vitamin D deficiency among children with asthma in Asia and Africa: a systematic review and meta-analysis

BACKGROUND

Several studies on the serum level of vitamin D and the percentage of vitamin D deficiency in children with asthma have been conducted in Asia and Africa, but the results have been inconsistent and inconclusive, requiring a systematic review and meta-analysis to assess the strength of the evidence.

OBJECTIVE

The objective of this review is to synthesize evidence on serum levels of vitamin D and the percentage of vitamin D deficiency among children with asthma in Asia and Africa.

METHODS

To identify relevant articles, a comprehensive search was conducted across various databases and repositories such as PubMed, Google Scholar, Hinary, Web of Science, ResearchGate, as well as gray literature sources. The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines were followed during the retrieval process. Data extraction was performed following a standardized format based on the JBI (Joanna Briggs Institute) data extraction guidelines. Microsoft Excel was utilized for data extraction, and subsequently, the data was exported to STATA 17 for further analysis. To assess the heterogeneity among the included studies, Cochrane Q-statistics and the I2 tests were employed. Publication bias was assessed using the Egger test and funnel plot.

RESULT

This meta-analysis investigated 33 articles encompassing a total of 3432 children diagnosed with asthma. The findings demonstrated that in low- or middle-income countries across Africa and Asia, children with asthma had an average serum vitamin D level of 21.9 ng/ml (95% confidence interval [CI]: 18.0-25.9 ng/ml), with 53.7% (95% CI: 40.5-66.9) experiencing vitamin D deficiency. Additionally, when considering the continent, children with asthma in Asia had an average serum vitamin D level of 18.5 ng/ml (95% CI: 13.8-23.3), while those in Africa had a level of 28.7 ng/ml (95% CI: 22.7-34.8). The analysis further explored different sub-group analyses. Depending on the study design, case-control studies yielded an average serum vitamin D level of 20.3 ng/ml (95% CI: 18.2-22.4), whereas cross-sectional studies resulted in 23.8 ng/ml (95% CI: 17.5-30.1). Based on publication year, studies published on or before 2015 had an average serum level of 21.0 ng/ml (95% CI: 18.0-24.0), while those published after 2015 had a level of 22.4 ng/ml (95% CI: 17.2-27.7). Moreover, when considering sample size, studies with 100 participants or less had an average serum level of 21.7 ng/ml (95% CI: 17.3-26.1), while studies with more than 100 participants had a level of 22.1 ng/ml (95% CI: 18.6-25.6).

CONCLUSION

Children with asthma in Asia and Africa were found to have low serum levels of vitamin D and a high percentage of vitamin D deficiency. This highlights the importance of early detection and monitoring of vitamin D levels in these children to prevent potential complications associated with vitamin D deficiency. Taking proactive measures to address and manage vitamin D deficiency is crucial for the well-being of children with asthma in these regions.

Efficacy of vitamin D supplementation in asthmatic children with vitamin D deficiency: A randomized controlled trial (ESDAC trial)

BACKGROUND

Vitamin D supplementations for asthma control had shown inconsistent results. We aimed to study efficacy and safety of vitamin D supplementation in asthmatic children who were vitamin D deficient.

METHODS

This double-blind, randomized controlled trial enrolled asthmatic children of 4-12 years of age who had 25-hydroxyvitamin D [25(OH)D] levels <20 ng/mL. The participants were randomized to receive either vitamin D orally 1000 IU/d for 9 months or similar-looking placebo. The primary outcomes were the proportion of children having the Childhood Asthma Control Test (CACT) score of ≥20 at the end of the treatment and adverse effects.

RESULTS

The trial included 250 children (125 in each group) with a mean age of 8.1 ± 2.3 years and 180 boys. The baseline parameters were similar between the groups, including CACT score (21.7 ± 4.2 vs 21.9 ± 3.6, vitamin D vs placebo). At the end of the study, the proportion of asthmatic children who had CACT score ≥ 20 was similar between vitamin D and placebo group (93.6% vs 92.0%, P = .625). The number of exacerbations of asthma and side effect profile was also identical between the groups. 25(OH)D levels increased significantly in the vitamin D group (18.06 ± 7.11 vs 12.03 ± 5.98 ng/mL, P < .001). The results did not change when we did subgroup analysis for children with baseline CACT score < 20 and 25(OH)D levels at the end of the study ≥20 ng/mL.

CONCLUSION

Vitamin D supplementation in asthmatic children with vitamin D deficiency did not improve control of asthma.

IL-35 and IL-37 are negatively correlated with high IgE production among children with asthma in Saudi Arabia

BACKGROUND

Asthma is one of the most prevalent inflammatory disorders among children in Saudi Arabia.

OBJECTIVE

This study aimed to determine the correlation between the serum levels of vitamin D, immunoglobulin E (IgE), and cytokine (interferon-gamma (IFN-γ), interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37) in relation to the severity of disease in patients with asthma.

METHODS

This case-control study was carried out at King Abdullah Specialist Children's Hospital, Saudi Arabia, and included 48 patients with asthma and 47 matched controls, aged 6-14 years. A validated questionnaire was administered to the participants, after which each patient with asthma underwent pulmonary function tests. The serum levels of vitamin D, IgE, IFN-γ, IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37 of each participant were also measured.

RESULTS

Patients with asthma demonstrated significantly higher IgE and cytokine (IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37) levels compared to the control group (p value < .001). The levels of IL-1β, IL-4, IL-10, and IL-13 were consistently positively correlated with the serum levels of IgE among patients with asthma. However, the IgE levels in patients with asthma were consistently negatively correlated with IL-35 and IL-37.

CONCLUSIONS

We found significantly higher levels of eosinophils, IgE, IL-1β, IL-4, IL-6, IL-10, IL-13, IL-35, and IL-37 in patients with asthma compared to the controls, but no relationship between vitamin D and asthma.