Objective: To probe into the correlation between vitamin D level and acute lower respiratory infection (ALRI) in children. Methods: PubMed

EMBase

the Cochrane library

CNKI

Wanfang and VIP database were retrieved to collect the case-control studies of vitamin D and ALRI in children published from Jan. 1st

1990 to May 31st

2019. The included articles were screened according to strict inclusion and exclusion criteria

and quality evaluation and heterogeneity tests were performed. Sensitivity analysis and subgroup analysis were carried out for the results. Data were collated and analyzed by RevMan 5.3. Results: A total of 10 articles were collected

including 1

749 samples

with 1

070 cases in the case group and 679 cases in the control group. Meta-analysis results showed: (1) The incidence of 25 hydroxy vitamin D (25(OH)D) deficiency in children with ALRI was higher than that in healthy children (OR=4.3

95%CI from 2.5 to 7.4

Z=526

P<0.000

01). (2) The 25(OH)D level of children with ALRI was lower than that of healthy children (WMD=-8.44

95%CI from -9.33 to -7.55

Z=18.63

P<0.000

001). The results of subgroup analysis showed that according to the area

the difference in 25(OH)D level between the ALRI group and the control group in Asia and Africa was statistically significant. According to the vitamin D level in the case group

there was statistically significant difference in level of 25(OH)D between the ALRI group with vitamin D insufficiency and deficiency (<30 ng/mL) and the control group. Conclusion: Serum 25(OH)D in children with ALRI is lower than that in healthy children

and 25(OH)D insufficiency and deficiency may be a risk factor for ALRI. Due to the limitation of the number of included literature

the above findings need to be validated by more high-quality literature.