Hair Drug Tests Agreed Well With Self-Reports for Cannabis But Poorly for Cocaine
In a clinical trial of 1,285 emergency department drug users, hair analysis and self-reported drug use showed high agreement for cannabis and street opioids, but poor agreement for cocaine and prescribed opioids.
Quick Facts
What This Study Found
Researchers compared hair analysis results with self-reported drug use (Timeline Follow Back) for four drug classes across 1,285 adult emergency department patients with moderate to severe drug problems.
Hair analysis and self-report showed high concordance for cannabis and street opioids but low to moderate concordance for cocaine and prescribed opioids. An important pattern emerged: people were significantly more accurate in reporting their primary drug of choice. Under-reporting of use given a positive hair test was always lower for the person's primary drug compared to secondary drugs.
Conversely, over-reporting of use given a negative hair test was higher for the drug of choice, suggesting some people reported using their preferred drug more than they actually did, or that hair analysis may not capture all patterns of use.
Key Numbers
1,285 participants from 6 US academic hospitals. High concordance for cannabis and street opioids. Low to moderate concordance for cocaine and prescribed opioids. Under-reporting was always lower for the participant's primary drug of choice.
How They Did This
Secondary analysis of a National Drug Abuse Treatment Clinical Trials Network randomized trial (NCT01207791). 1,285 adult ED patients with moderate to severe drug problems were assessed at 3, 6, and 12 months. Both hair analysis and Timeline Follow Back self-reports covered the same 90-day periods.
Why This Research Matters
Clinical trials of addiction treatments rely on self-reported drug use, and there are longstanding concerns about accuracy. This study demonstrates that for cannabis specifically, self-report is quite reliable when compared to biological verification via hair analysis. This validates cannabis use data from clinical trials that relied on self-report.
The Bigger Picture
The reliability of self-reported drug use is a fundamental question in addiction research. This study provides reassurance that cannabis self-reports are generally trustworthy, while highlighting that cocaine and prescribed opioid self-reports should be verified with biological measures when accuracy is critical.
What This Study Doesn't Tell Us
The sample consisted of people with moderate to severe drug problems presenting to emergency departments, which may not represent all drug users. Hair analysis itself has limitations: it may not detect very light use, results can be affected by hair treatments, and some populations may decline to provide hair samples. The 90-day recall window is long for self-report accuracy.
Questions This Raises
- ?Why is concordance higher for cannabis than cocaine?
- ?Is it because cannabis stays in hair longer, because cannabis use is more routine and therefore easier to recall, or because cocaine use is more stigmatized?
- ?Would newer drug testing methods (oral fluid, sweat patches) show different concordance patterns?
Trust & Context
- Key Stat:
- High concordance between hair analysis and self-report for cannabis across 3, 6, and 12 month assessments.
- Evidence Grade:
- Moderate evidence from a large multi-center clinical trial with both biological and self-report measures collected at multiple time points.
- Study Age:
- Published in 2016. Hair analysis methodology and self-report instruments continue to be refined.
- Original Title:
- Hair analysis and its concordance with self-report for drug users presenting in emergency department.
- Published In:
- Drug and alcohol dependence, 167, 149-55 (2016)
- Database ID:
- RTHC-01264
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Do people accurately report their cannabis use?
This study suggests yes, at least for people with established drug use patterns. Hair analysis, which is difficult to fake, showed high agreement with self-reported cannabis use across multiple time points.
Can hair tests detect cannabis use?
Yes. Cannabis metabolites are incorporated into hair as it grows and can be detected for approximately 90 days. This study used hair analysis as a biological benchmark to validate self-reported use.
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Cite This Study
https://rethinkthc.com/research/RTHC-01264APA
Sharma, Gaurav; Oden, Neal; VanVeldhuisen, Paul C; Bogenschutz, Michael P. (2016). Hair analysis and its concordance with self-report for drug users presenting in emergency department.. Drug and alcohol dependence, 167, 149-55. https://doi.org/10.1016/j.drugalcdep.2016.08.007
MLA
Sharma, Gaurav, et al. "Hair analysis and its concordance with self-report for drug users presenting in emergency department.." Drug and alcohol dependence, 2016. https://doi.org/10.1016/j.drugalcdep.2016.08.007
RethinkTHC
RethinkTHC Research Database. "Hair analysis and its concordance with self-report for drug ..." RTHC-01264. Retrieved from https://rethinkthc.com/research/sharma-2016-hair-analysis-and-its
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.