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

Table 4 Summary of subgroup analyses of both observational studies and experimental studies

	Subjects (n)		95% CI	Heterogeneity (χ2)	P1
Observational studies		Odds ratio (OR)
H. pylori test methods
ELISA serum IgG	12372	2.16	1.49-3.14	9.27	0.10
Histological biopsy	906	2.17	0.90-5.26	28.85	< 0.0001
UBT	1475	5.88	2.27-15.23	1.53	0.47
Age
Child	1358	4.76	1.73-13.08	0.05	0.83
Adolescent	1972	2.85	1.68-4.31	0.22	0.89
Adult	3101	1.55	0.67-3.62	28.41	< 0.0001
Randomized controlled trials2		Weighted mean difference (WMD)
Hemoglobin (g/L)
Age
Child	300	0.65	-1.52-2.82	0.74	0.39
Adolescent and adult	35	25.03	9.69-40.37	0.67	0.41
Therapy
PPI	322	0.95	-2.98-4.87	3.71	0.16
Bismuth	13	32.00	9.37-54.63	-	-
H. pylori test methods
Histological biopsy	223	7.03	-9.41-23.47	2.79	0.10
UBT	35	25.03	9.69-40.37	0.67	0.41
Serum ferritin (μg/L)
Age
Child	300	0.70	-1.01-2.41	0.57	0.45
Adolescent and adult	121	14.79	2.53-27.05	17.91	0.0001
Therapy
PPI	322	7.15	-6.45-20.75	7.68	0.002
Bismuth	99	11.55	0.09-23.01	13.61	0.0002

¹P-value tested for heterogeneity of subgroups;

²Data were derived from hemoglobin changes and serum ferritin changes.