Table 2.

Summary odds ratios/relative ratios and 95 % confidence intervals of colorectal, colon and rectal cancer for the highest v. the lowest/non coffee consumption in strata of geographic area, sex and/or type of controls and/or follow-up period

	Colorectal cancer						Colon cancer						Rectal cancer
	No. of comparisons/studies	No. of cases	OR/RR	95 % CI	P*	I 2 (%)†	No. of comparisons/studies	No. of cases	OR/RR	95 % CI	P*	I 2 (%)†	No. of comparisons/studies	No. of cases	OR/RR	95 %CI	P*	I 2 (%)†
Case–control studies
Overall effect	37/25	15 522	0·85	0·75, 0·97	<0·001	64	17/14	9191	0·79	0·67, 0·95	<0·001	68	14/12	4996	0·95	0·79, 1·15	0·02	53
Geographic area
America	14/9	7847	0·90	0·77, 1·05	0·01	58	8/6	4970	0·88	0·70, 1·10	0·02	64	4/3	2347	1·00	0·85, 1·18	0·34	8
Asia	13/6	2062	0·75	0·49, 1·16	<0·001	80	6/5	1534	0·77	0·46, 1·29	<0·001	79	6/5	905	0·77	0·45, 1·33	0·002	77
Europe	10/10	5613	0·73	0·57, 0·93	0·009	59	3/3	2687	0·68	0·57, 0·81	0·33	9	4/4	1744	1·03	0·84, 1·25	0·40	0
Type of controls
Hospital	17/11	7768	0·78	0·63, 0·97	<0·001	74	7/6	4273	0·80	0·60, 1·08	0·004	71	6/5	2614	0·97	0·71, 1·33	0·009	67
Population	20/14	7754	0·84	0·71, 1·00	<0·001	60	10/8	4918	0·79	0·61, 1·01	0·002	69	8/7	2382	0·95	0·82, 1·10	0·25	24
Sex
Males	13/11	7046	0·96	0·73, 1·25	<0·001	78	9/9	4033	0·86	0·62, 1·18	<0·001	77	5/5	1754	1·13	0·69, 1·86	<0·001	80
Females	12/10	5530	0·82	0·73, 0·93	0·11	35	8/8	3350	0·80	0·63, 1·03	0·02	56	5/5	1234	0·87	0·71, 1·08	0·74	0
Cohort studies
Overall effect	27/16	10 443	0·94	0·88, 1·01	0·85	0	16/13	4838	0·93	0·86, 1·01	0·51	0	16/13	2740	0·98	0·88, 1·09	0·46	0
Geographic area
America	6/4	1853	0·92	0·82, 1·03	0·83	0	3/3	1380	0·93	0·81, 1·06	0·48	0	3/3	327	1·17	0·71, 1·92	0·16	42
Asia	7/4	2794	0·93	0·82, 1·05	0·18	33	6/4	1848	0·89	0·76, 1·03	0·16	38	4/3	950	1·02	0·83, 1·26	0·95	0
Europe	14/8	5796	0·96	0·88, 1·06	0·94	0	7/6	1610	0·98	0·86, 1·11	0·71	0	9/7	1463	0·98	0·84, 1·14	0·38	7
Sex
Males	11/9	3562	0·97	0·87, 1·08	0·97	0	7/7	1543	0·99	0·85, 1·14	0·81	0	7/7	1026	1·02	0·85, 1·23	0·44	0
Females	10/9	3707	0·93	0·81, 1·05	0·49	3	7/7	1935	0·91	0·77, 1·07	0·21	29	7/7	939	1·02	0·83, 1·25	0·29	19
Follow-up periods
<10 years	12/7	2675	0·92	0·85, 1·01	0·35	10	6/5	1582	0·90	0·81, 1·00	0·30	17	4/4	774	0·92	0·78, 1·08	0·54	0
≥10 years	15/9	7771	0·96	0·88, 1·05	0·98	0	10/8	3256	0·98	0·87, 1·09	0·62	0	12/9	1969	1.03	0.90, 1.19	0.40	5

RR, relative ratio.

*P value for heterogeneity.

†I ² is interpreted as the proportion of total variation across studies due to heterogeneity rather than chance.