Table 2.

Basic characteristics of studies comparing serum vitamin levels between the successful H. pylori eradication groups and the failed groups.

Study	Year	Area	Design	Age of successful groups	No. of successful groups (male/female)	Age of failed groups	No. of failed groups (male/female)	Quality
Vitamin D
Yildirim et al. (57)	2017	Turkey	Cross-sectional	N/A	170 (N/A)	N/A	50 (N/A)	7*
Shahawy et al. (58)	2018	Egypt	Cross-sectional	18–80 y	105 (N/A)	18–80 y	45 N/A)	7*
Magsi et al. (2)	2021	Pakistan	Cross-sectional	18–60 y	88 (42/46)	18–60 y	36 (18/18)	8*
Shatla et al. (59)	2021	Saudi Arabia	Cross-sectional	N/A	109 (N/A)	N/A	42 (N/A)	7*
Shafrir et al. (56)	2021	Israel	Cross-sectional	N/A	45821 (N/A)	N/A	29722 (N/A)	9*

N/A, not available; y, years;

^*The “star system” of the Newcastle–Ottawa scale.