Table 3.

Subgroup analysis of relative risks for association between body mass index (BMI) and gallbladder cancer risk.

	Overweight					Obesity
	Studies, n	RR (95% CI)	ph	Q	I2,%	Studies, n	RR (95% CI)	ph	Q	I2,%
Study design
Cohort studies	12	1.15 (1.02–1.29)	0.04	22.03	45.5	12	1.62 (1.45–1.81)	0.28	19.98	14.9
Case-control studies	8	1.16 (0.96–1.41)	0.68	5.75	0	8	1.37 (1.10–1.71)	0.39	9.52	5.5
Follow-up time
>10 years	6	1.12 (1.00–1.27)	0.04	17.78	49.4	9	1.65 (1.49–1.83)	0.40	13.58	4.3
<10 years	2	1.52 (1.06–2.19)	0.54	1.22	0	3	1.69 (0.91–3.17)	0.10	6.32	52.5
Control source
Hospital	3	1.14 (0.61–2.03)	0.30	2.39	16.4	4	1.07 (0.66–1.74)	0.57	2.03	0
Population	4	1.18 (0.96–1.46)	0.67	3.19	0	4	1.43 (1.09–1.89)	0.30	6.12	18.3
Sex
Men	9	1.06 (0.94–1.20)	0.24	10.33	22.5	11	1.42 (1.21–1.66)	0.85	5.63	0
Women	8	1.26 (1.13–1.40)	0.45	6.84	0	10	1.67 (1.38–2.02)	0.06	16.38	45.0
Geographic region
Asia	6	1.19 (0.98–1.45)	0.06	15.00	46.7	7	1.48 (1.26–1.74)	0.43	8.07	0.9
Non-Asia	9	1.14 (1.05–1.25)	0.43	12.20	1.7	13	1.58 (1.40–1.80)	0.22	22.38	19.6
BMI ascertainment
Self-reported	7	1.18 (1.01–1.36)	0.46	9.74	0	7	1.65 (1.32–2.05)	0.20	12.16	26.0
Measured	7	1.14 (1.01–1.30)	0.04	17.40	48.3	8	1.51 (1.29–1.77)	0.20	13.52	26.1
Adjustment for confounders smoking
Yes	10	1.16 (1.02–1.31)	0.16	20.42	26.5	11	1.55 (1.31–1.83)	0.21	19.06	21.3
No	5	1.14 (0.98–1.32)	0.21	7.10	29.5	9	1.59 (1.40–1.80)	0.32	12.61	12.8
Alcohol intake
Yes	7	1.27 (1.10–1.47)	0.37	10.87	8.0	7	1.64 (1.31–2.07)	0.15	13.31	32.4
No	8	1.08 (0.98–1.19)	0.25	12.59	20.6	13	1.56 (1.40–1.73)	0.36	18.44	7.8

RR, relative risk; CI, confidence interval; BMI, body mass index; p_h, p-value for heterogeneity; Q, Cochran’s Q statistics.