Details of the case–control studies meeting the inclusion criteria
| Case–control study | Country | Case selection | N (% men) and age of cases | Control selection | N (% men) and age of controls | Measurement of coffee consumption | Outcome | NOS quality score |
| Gallus et al (study 1)37 | Italy | Hospital | 501 (75) aged 20–75 (median 60) | Patients with non-cancer disorders in same hospital and from same catchment area | 1552 (74) aged 18–75 (median 56) | FFQ | HCC | 5 |
| Gallus et al (study 2)37 | Greece | Hospital | 333 (85) aged 31–79 (median 65) | Patients with non-cancer disorders in same hospital | 360 (83) aged 24–79 (median 65) | FFQ | HCC | 5 |
| Gelatti et al 42 | Italy | Hospital | 250 (82) aged less than 80 (mean 63.8) | Patients without liver disease in same hospital | 500 aged less than 80 (mean 64.1) | FFQ | HCC | 7 |
| Ohfuji et al 43 | Japan | Attending hospital for HCV follow-up | 73 (47) (mean age 68.9) | Attending hospital for HCV follow-up | 253 (52) (mean age 68.3) | FFQ | HCC | 5 |
| Tanaka et al 33 | Japan | Hospital | 209 (68) aged 40–79 (mean 67) | Community controls randomly selected | 1308 (50) (mean 57) | FFQ | HCC | 4 |
| Montella et al 32 | Italy | Hospital | 185 (81) aged 43–84 (median 66) | Patients in same hospital | 412 (68) aged 40–82 (median 65) | FFQ | HCC | 5 |
| Leung et al 45 | Hong Kong | Attending hospital for HBV follow-up | 109 (79) aged ≤39 to ≥60 | Attending hospital for HBV follow-up | 125 (82) aged ≤39 to ≥60 | FFQ | HCC | 5 |
| Stucker et al 44 | France | Hospital | 165 (100) aged <75 | Patients without liver disease in same hospital | 142 (100) aged <75 | FFQ | HCC | 4 |
FFQ, food frequency questionnaire; HBV, hepatitis B virus; HCC, hepatocellular carcinoma; HCV, hepatitis C virus; NOS, Newcastle-Ottawa Scale.