Does Helicobacter pylori infection play a role in iron deficiency anemia? A meta-analysis

Abstract

Aim: To perform a meta-analysis of observational studies and randomized controlled trials (RCTs) on the association between Helicobacter pylori (H. pylori) and iron deficiency anemia (IDA).

Methods: A defined search strategy was used to search Medline, Embase, the Cochrane Library, Clinical Trials, Cochrane Central Register of Controlled Trials, Premedline and Healthstar. Odds ratio (OR) was used to evaluate observational epidemiology studies, and weighted mean difference (WMD) was used to demonstrate the difference between control and intervention groups.

Results: Fifteen observational studies and 5 RCTs were identified and used for calculation. The pooled OR for observational studies was 2.22 (95% CI: 1.52-3.24, P < 0.0001). The WMD for hemoglobin (HB) was 4.06 g/L (95% CI: -2.57-10.69, P = 0.01), and the WMD for serum ferritin (SF) was 9.47 mug/L (95% CI: -0.50-19.43, P < 0.0001). Results were heterogeneous for all comparisons.

Conclusion: This meta-analysis on observational studies suggests an association between H. pylori and IDA. In RCTs, eradication of H. pylori can improve HB and SF levels but not significantly.

Figure 1

Flow chart showing the trial flow for selection of RCTs and observational studies to be included. RCT: Randomized controlled trial; HP: H. pylori; IDA: Iron deficiency anemia; HB: Hemoglobin; SF: Serum ferritin.

Figure 2

Forest plot of the observational studies. M-H, Random: Mantel-Haenszel heterogeneity random effects model. Horizontal lines = 95% CI. The rectangles represent the point estimates of the study and the size of the rectangle represents the weight given to each study in the meta-analysis. The diamond represents the summary estimate; the size of the diamond represents the CIs of the summary estimate.

Figure 3

The treatment effect and underlying connection between H. pylori and IDA. A: Weighted mean difference (WMD) forest plots of HB (g/L) involved in the meta-analysis; B: Forest plots of studies estimate changes in SF (μg/L) level. IV, Random: Inverse variance heterogeneity random effects model. Horizontal lines = 95% CI. The size of the data marker corresponds to the weight of that study. The diamond represents the summary estimate. The result favors experimental groups.

Figure 4

Funnel plots without (A) and with (B) trim and fill. The pseudo 95% CI is computed as part of the analysis that produces the funnel plot, and corresponds to the expected 95% CI for a given standard error (SE). OR: Odds ratio.