Table 2: Overall effect estimates for Helicobacter pylori infection and lung cancer according to study characteristics.

StudyNo. of studiesRandom-effects model: Heterogeneity between studies
Overall OR (95% CI) valuea value

All72.29 (1.34–3.91)<0.0183.9%
Sensitivity analysis
 All except study by Ece et al. [13]b61.88 (1.14–3.18)<0.0180.9%
Study design
 Cohort12.63 (1.95–3.55)NANA
 Case-control62.28 (1.19–4.39)<0.0179.9%
Time of Zhuo et al. [18]c
 Published in time frame covered in Zhuo et al. [18] 43.11 (1.07–9.04)<0.0180.9%
 Published after Zhuo et al. [18]31.87 (0.93–3.37)<0.0190.1%
Histology of lung cancer
 Lung adenocarcinoma11.1 (0.75–1.6)NANA
 Lung squamous cell carcinoma11.1 (0.77–1.7)NANA
Quality of included studiesd
 High quality11.09 (0.85–1.41)NANA
 Medium quality42.12 (1.24–3.61)0.0561.1%
 Low quality26.12 (0.90–41.38)0.0182.6%

OR: Odds ratio; CI: confidence interval; NA: not available.
a value obtained by Cochrane test.
bEce et al. [13] is the one of the included studies which has wider confidence interval.
cZhuo et al. [18] is the recent meta-analysis done on this subject.
dQuality of-included studies was assessed using Newcastle-Ottawa Scale.