Table 3. Biliary findings in patients with opium addiction in different studies .
| Author | Year of study | Study design | Country | Imaging | Sample size (addicts/control) | Main finding |
| Chuah et al5 | 2003 | Case-Control | Singapore | TUS | 7 / 7 | Dilated CBD in OA |
| Farahmand et al4 | 2007 | Cross-sectional | Iran | TUS | 110 / 0 | Dilated CBD in 65.5% of OA |
| Zahedi-Nejad et al11 | 2010 | Case-Control | Iran | TUS | 121 / 142 | Dilated CBD in OA |
| Sharma et al10 | 2013 | Case series | India | EUS | 15 / 0 | Dilated CBD in OA |
| Dadpour et al12 | 2016 | Cross-sectional | Iran | TUS, ERCP | 50 / 0 | Dilated CBD in OA |
Abbreviations: TUS, transabdominal ultrasonography; EUS, endoscopic ultrasonography; ERCP, endoscopic retrograde cholangiopancreatography; CBD, common bile duct; OA, opium addict.