Effects of chronic cannabis smoking on lung health
Official title: Chronic Cannabis Smoking, Oxidative Stress and the Pulmonary Innate Immune Response
Run by University of Colorado, Denver · NCT02480283 · Data updated 2026-11-12
This study is trying to see how long-term cannabis smoking affects lung health in regular users compared to non-smokers.
Quick facts
| Study type | Observational |
|---|---|
| Ages | 18 Years to 55 Years |
| Sex | All |
| Enrollment | 100 (estimated) |
| Sponsor | University of Colorado, Denver Academic / other |
| Locations | 1 site (Aurora, Colorado) |
| Status | Recruiting |
| Started | November 11, 2015 |
| Main results expected | July 2026 |
| Study ends | July 2027 |
| Registry record updated | October 10, 2024 |
| Trial ID | NCT02480283 on ClinicalTrials.gov |
Is this trial a fit for you?
✓Likely a good fit
Ideal candidates include individuals who smoke cannabis daily or nearly daily with significant exposure, while controls are non-users of cannabis and tobacco.
✕Probably not a fit
Patients who have never smoked cannabis or have a significant history of tobacco use may not benefit from this study.
A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.
What this trial studies
This observational study aims to evaluate the impact of chronic cannabis smoking on pulmonary health, specifically focusing on lung physiology and the function of alveolar macrophages. The research is motivated by the increasing prevalence of cannabis use and the unclear effects it has on lung health, particularly in light of higher THC concentrations in today's cannabis compared to the past. The study will involve various interventions, including bronchoscopy and chest X-rays, to assess oxidative stress and immune response in habitual cannabis smokers compared to non-users. The findings could provide valuable insights into the respiratory consequences of cannabis smoking.
Why it matters
Potential benefit: If successful, this study could enhance understanding of the respiratory effects of cannabis smoking and inform public health guidelines.
How similar studies have gone: While there is limited data on the effects of chronic cannabis smoking in humans, previous animal studies have indicated potential risks, making this a novel investigation.
Who can join: the full rules
Show full inclusion / exclusion criteria
Inclusion Criteria: INCLUSION CRITERIA for CANNABIS USING patient: Subjects will be eligible if they meet ALL of the following criteria: 1. Daily or near daily cannabis use (inhaled via joint/cigarette or pipe) equivalent to AT LEAST 20 "joint years" (number of joints/cigarettes per day multiplied by number of years during which cannabis was smoked) by self-report and validated through urine drug screen. 2. Never or limited exposure to inhaled tobacco products (equivalent to LESS THAN one "pack year" in a lifetime) by selfreport and validated through negative urine cotinine screen. 3. Capacity to answer screening questions and provide informed consent at time of interview, along with contact information INCLUSION CRITERIA for CONTROL patient: Subjects will be eligible if they meet all of the following: 1. No cannabis use ever by self-report, and validated through urine drug screen. 2. Never users of tobacco/cigarettes 3. Capacity to answer screening questions and provide informed consent at time of interview, along with contact information. Exclusion Criteria: EXCLUSION CRITERIA for CANNABIS USING patient: Subjects will be ineligible if they meet ANY of the following criteria: 1. LESS THAN near daily cannabis use (inhaled via joint/cigarette or pipe) equivalent to LESS THAN 20 "joint years" (number of joints/cigarettes per day multiplied by number of years during which cannabis was smoked) or a negative urine drug screen (for cannabis) 2. Inhaled tobacco product exposure EXCEEDING one "pack year" or a positive urine cotinine screen 3. Elevated AUDIT-C score: A 3 item questionnaire to identify subjects with alcohol use disorders. 4. Prior medical history of liver disease: cirrhosis, total bilirubin \> 2.0 mg/dL or albumin \<3 5. Prior medical history of myocardial infarction or congestive heart failure 6. Prior medical history of end-stage renal disease or serum creatinine \>3 mg/dL 7. Prior history of or current use of illicit drug use defined as a positive toxicology screen for opiates or cocaine 8. Prior history of diabetes mellitus 9. Prior history of chronic obstructive pulmonary disease (COPD) or asthma that is not clinically controlled (have not required systemic corticosteroids in the past month) 10. Prior history of HIV, not controlled or on medication 11. Peripheral white blood cell count of less than 3000 12. Acute worsening (\<7 days) in respiratory symptoms (such as change in cough frequency or sputum production, fever, dyspnea, abnormal chest radiograph), or room air pulse oximetry of \< 92% at rest or spirometry of \< 50% predicted for FEV1 and FVC 13. Use of systemic antibiotics for any reason in the past month (4 weeks) 14. Failure of a subject or the subject's substance abuse counselor to provide assent 15. Nutritional risk index of less than 95 16. Age \< 21 or \> 55 (using an age of 55 limits the likelihood of comorbid conditions that may increase the risk of adverse events with bronchoscopy) 17. Pregnancy 18. Decisionally challenged 19. Prisoners. EXCLUSION CRITERIA for CONTROL patient: Subjects will be ineligible to participate if they meet ANY of the following criteria: 1. History of inhaled cannabis exposure EXCEEDING one "joint year" or positive urine toxicology screen (for cannabis) 2. History of inhaled tobacco product exposure EXCEEDING one "pack year" or a positive urine cotinine screen 3. Elevated AUDIT-C score: A 3 item questionnaire to identify subjects with alcohol use disorders. 4. Prior medical history of liver disease: cirrhosis, total bilirubin \> 2.0 mg/dL or albumin \<3 5. Prior medical history of myocardial infarction or congestive heart failure 6. Prior medical history of end-stage renal disease or serum creatinine \>3 mg/dL 7. Prior history of or current use of illicit drug use defined as a positive toxicology screen for opiates or cocaine 8. Prior history of diabetes mellitus 9. Prior history of chronic obstructive pulmonary disease (COPD) or asthma that is not clinically controlled (have not required systemic corticosteroids in the past month) 10. Prior history of HIV, not controlled or on medication 11. Peripheral white blood cell count of less than 3000 12. Acute worsening (\<7 days) in respiratory symptoms (such as change in cough frequency or sputum production, fever, dyspnea, abnormal chest radiograph), or room air pulse oximetry of \< 92% at rest or spirometry of \< 50% predicted for FEV1 and FVC 13. Use of systemic antibiotics in the past month (4 weeks) 14. Failure of a subject or the subject's substance abuse counselor to provide assent 15. Nutritional risk index of less than 95 16. Age \< 21 or \> 55 17. Pregnancy 18. Decisionally challenged 19. Prisoners.
Where it's running
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University of Colorado, Denver
Aurora, Colorado, United States Recruiting
Study contacts
- Principal investigator: Ellen L Burnham, MD — University of Colorado, Denver
- Study coordinator: Jeffrey D McKeehan, MSN
- Email: jeffrey.mckeehan@ucdenver.edu
- Phone: 303-724-6080
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How to take part
- Review the eligibility criteria above with your treating physician.
- Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
- Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.