Metformin Use and Lung Cancer Risk in Diabetic Patients: A Systematic Review and Meta-Analysis

Table 3

A subgroup analysis of metformin use and lung cancer risk in patients with diabetes.

Subgroups	Pooled RR			Heterogeneity
		RR (95% CI)	value	value	value	(%)
Study design
Case-control	3	0.70 (0.47-1.03)	0.07	7.51	0.02	73
Cohort	10	0.91 (0.85-0.98)	0.008	26.33	0.002	66
Study location
Asia	4	0.76 (0.55-1.06)	0.1	16.89	0.0007	82
North America	4	0.92 (0.71-1.19)	0.51	8.43	0.04	64
Europe	5	0.90 (0.86-0.94)	<0.0001	7.33	0.12	45
Source of case
Population-based	7	0.88 (0.76-1.01)	0.07	18.59	0.005	68
Hospital-based	6	0.89 (0.80-0.99)	0.04	16.88	0.005	70
Control drugs
None	8	0.89 (0.77-1.03)	0.13	22.37	0.002	69
Sulfonylurea	5	0.91 (0.86-0.96)	0.001	5.09	0.28	21
Insulin	3	0.97 (0.75-1.26)	0.84	0.06	0.97	0
Adjustment
BMI	8	0.91 (0.80-1.03)	0.12	16.41	0.02	57
Smoking	6	0.86 (0.75-1.00)	0.05	14.11	0.01	65
HbA1C	4	0.83 (0.65-1.07)	0.16	8.31	0.04	64
Alcohol	5	0.93 (0.83-1.05)	0.27	8.07	0.09	50
Glucose-lowering drugs	4	0.90 (0.84-0.97)	0.004	3.51	0.32	15