Table 2. Summary of meta-analysis results for BMI and bladder cancer risk.

Analysis specification	Studies	SRR (95%CI)	I2 (%)	P*
Overweight
All	14	1.03 (0.95-1.11)	30.4	0.133
Mean age
≥50	5	1.01 (0.43-1.21)	24.8	0.104
<50	7	0.94 (0.87-1.34)	0.0	0.419
Year of publication
≥2008	6	1.03 (0.89-1.09)	3.4	0.411
<2008	8	1.05 (0.78-1.28)	0.0	0.633
Follow-up duration
≥10 years	8	0.96 (0.57-1.23)	0.0	0.857
<10 years	6	1.07 (0.89-1.18)	16.2	0.153
Sample size
≥1,000,000	4	1.05 (0.45-1.37)	0.0	0.477
<1,000,000	10	1.01 (0.96-1.10)	54.6	0.031
Assessment of BMI
Measured	6	1.10 (0.91-1.23)	53.4	0.008
Self-reported	7	1.02 (1.86-1.15)	12.9	0.301
Geographic area
Asia	3	1.02 (0.97-1.08)	0	0.675
Europe	4	1.06 (0.97-1.73)	47.0	0.100
America	4	1.03 (0.79-1.34)	0.0	0.861
Multi–international centers	2	1.09 (0.98-1.56)	12.9	0.351
Physical activity
Yes	2	1.07 (0.94-1.29)	35.9	0.191
No	12	1.15 (1.00-1.98)	42.7	0.121
Family history of cancer
Yes	2	1.15(0.93–1.29)	12.8	0.543
No	12	1.06(1.00–1.19)	36.1	0.087
Obesity
All	14	1.10 (1.03-1.17)	58.5	0.003
Mean age
≥50	6	1.19 (1.08-1.22)	19.9	0.267
<50	6	1.01 (1.09-1.68)	56.8	0.061
Year of publication
≥2008	6	1.10 (1.53-1.89)	27.1	0.171
<2008	8	1.02 (1.14-1.40)	66.2	0.000
Follow-up duration
≥10 years	8	1.30 (1.02-1.39)	0.0	0.424
<10 years	6	1.07 (1.04-1.74)	10.3	0.231
Sample size
≥1,000,000	4	1.14 (1.01-1.61)	24.8	0.200
<1,000,000	10	1.04 (1.08-1.54)	37.1	0.112
Assessment of BMI
Measured	7	1.09(1.02–1.13)	12.5	0.354
Self-reported	6	1.24(1.09–1.40)	32.4	0.187
Geographic area
Europe	3	1.84 (1.55-2.19)	0.0	0.651
America	4	1.97 (1.40-2.75)	18.8	0.214
Asia	3	2.29 (1.46-3.58)	17.1	0.341
Smoking
Yes	2	1.11(1.05–2.16)	24.1	0.145
No	12	1.17(1.05–1.46)	8.81	0.653
Family history of cancer
Yes	2	1.13(1.07–1.19)	29.9	0.201
No	12	1.09(1.04–1.13)	1.83	0.412

BMI: Body mass index, SRR: The summary relative risk, *P value for heterogeneity.