title: Opium use and risk of mortality from digestive diseases: a prospective cohort study.
abstract: OBJECTIVE
  Opium use, particularly in low doses, is a common practice among adults in northeastern Iran. We aimed to investigate the association between opium use and subsequent mortality from disorders of the digestive tract.
  
  
  METHODS
  We used data from the Golestan Cohort Study, a prospective cohort study in northeastern Iran, with detailed, validated data on opium use and several other exposures. A total of 50,045 adults were enrolled during a 4-year period (2004-2008) and followed annually until December 2012, with a follow-up success rate of 99%. We used Cox proportional hazard regression models to evaluate the association between opium use and outcomes of interest.
  
  
  RESULTS
  In all, 8,487 (17%) participants reported opium use, with a mean duration of 12.7 years. During the follow-up period 474 deaths from digestive diseases were reported (387 due to gastrointestinal cancers and 87 due to nonmalignant etiologies). Opium use was associated with an increased risk of death from any digestive disease (adjusted hazard ratio (HR)=1.55, 95% confidence interval (CI)=1.24-1.93). The association was dose dependent, with a HR of 2.21 (1.57-3.31) for the highest quintile of cumulative opium use vs. no use (Ptrend=0.037). The HRs (95% CI) for the associations between opium use and malignant and nonmalignant causes of digestive mortality were 1.38 (1.07-1.76) and 2.60 (1.57-4.31), respectively. Increased risks were seen both for smoking opium and for ingestion of opium.
  
  
  CONCLUSIONS
  Long-term opium use, even in low doses, is associated with increased risk of death from both malignant and nonmalignant digestive diseases.
authors.affiliation: 1] Digestive Disease Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran [2] These authors contributed equally to this work.
authors.forename: Masoud M
authors.initials: MM
authors.lastname: Malekzadeh
authors.forename: Hooman
authors.initials: H
authors.lastname: Khademi
authors.forename: Akram
authors.initials: A
authors.lastname: Pourshams
authors.forename: Arash
authors.initials: A
authors.lastname: Etemadi
authors.forename: Hossein
authors.initials: H
authors.lastname: Poustchi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Bagheri
authors.forename: Masoud
authors.initials: M
authors.lastname: Khoshnia
authors.forename: Amir Ali
authors.initials: AA
authors.lastname: Sohrabpour
authors.forename: Ali
authors.initials: A
authors.lastname: Aliasgari
authors.forename: Elham
authors.initials: E
authors.lastname: Jafari
authors.forename: Farhad
authors.initials: F
authors.lastname: Islami
authors.forename: Shahryar
authors.initials: S
authors.lastname: Semnani
authors.forename: Christian C
authors.initials: CC
authors.lastname: Abnet
authors.forename: Paul D P
authors.initials: PD
authors.lastname: Pharoah
authors.forename: Paul
authors.initials: P
authors.lastname: Brennan
authors.forename: Paolo
authors.initials: P
authors.lastname: Boffetta
authors.forename: Sanford M
authors.initials: SM
authors.lastname: Dawsey
authors.forename: Reza
authors.initials: R
authors.lastname: Malekzadeh
authors.forename: Farin
authors.initials: F
authors.lastname: Kamangar
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004066:Digestive System Diseases / Q000401:mortality*; D055030:Drug Users; D005260:Female; D006801:Humans; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009892:Opium / Q000009:adverse effects*; D011446:Prospective Studies; D012306:Risk; D015996:Survival Rate
chemical_list: D009892:Opium