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Prescription opioid diversion and abuse are major public health issues in the United States and internationally. Street prices of diverted prescription opioids can provide an indicator of drug availability, demand, and abuse potential, but these data can be difficult to collect. Crowdsourcing is a rapid and cost-effective way to gather information about sales transactions. We sought to determine whether crowdsourcing can provide accurate measurements of the street price of diverted prescription opioid medications.
To assess the possibility of crowdsourcing black market drug price data by cross-validation with law enforcement officer reports.
Using a crowdsourcing research website (StreetRx), we solicited data about the price that site visitors paid for diverted prescription opioid analgesics during the first half of 2012. These results were compared with a survey of law enforcement officers in the Researched Abuse, Diversion, and Addiction-Related Surveillance (RADARS) System, and actual transaction prices on a “dark Internet” marketplace (Silk Road). Geometric means and 95% confidence intervals were calculated for comparing prices per milligram of drug in US dollars. In a secondary analysis, we compared prices per milligram of morphine equivalent using standard equianalgesic dosing conversions.
A total of 954 price reports were obtained from crowdsourcing, 737 from law enforcement, and 147 from the online marketplace. Correlations between the 3 data sources were highly linear, with Spearman rho of 0.93 (
Crowdsourced data provide a valid estimate of the street price of diverted prescription opioids. The (ostensibly free) black market was able to accurately predict the relative pharmacologic potency of opioid molecules.
The United States has a high level of concern with the diversion and public health consequences associated with the nonmedical use of prescription opioid analgesics [
Street price data have many applications. They are routinely collected by law enforcement agencies, which rely on accurate street prices for agents to be credible buyers or sellers in undercover operations. On a policy level, the Drug Enforcement Administration cited street price data to justify assigning buprenorphine to Schedule III, a lesser category of regulation than methadone, oxycodone, and morphine [
Although street price data are collected by local law enforcement, they have only occasionally been reported at a national level and are rarely made available for public health research [
An earlier study by our group suggested the Internet was an infrequent source of diverted drugs [
Given the interest but lack of scientific efforts to collect street price information, we sought to evaluate whether online crowdsourcing could be used to measure black market street prices. Crowdsourcing is a method for harnessing distributed human intelligence, where small pieces of independently derived information are systematically collected, often using electronic tools [
Launched on November 1, 2010, StreetRx is a collection of databases and websites, which gathers, organizes, and displays street price data on diverted pharmaceutical controlled substances for public health research purposes (see
Submissions for opioid analgesics that were received from the United States between January 1 and June 30, 2012, and contained data about formulation and dose strength were considered for this report. Based on previous crowdsourcing experiments, we deemed it necessary to have a systematic way to reduce noise in the data and identify less credible submissions. Outlier prices identified by site users as “cheap” or “overpriced” on a 5-point visual analog scale were excluded; approximately one quarter of all submissions were rated in these 2 categories. Because duplicate submissions for the same drug from the same IP address less than 10 seconds apart most likely indicated submission errors, only one of the dyad was retained.
StreetRx is written in PHP programming language, with OpenLayers and jQuery user interface components. The data are stored in a MySQL relational database, on a scalable, secure hosting service with a proven track record of managing traffic spikes and high user load. Because the hosting provider also specializes in politically controversial content, the system is designed to resist attempts at being shut down due to objections to the site content. It relies on map tiles from Google Maps, but uses OpenLayers to render the map interface. The site also contains Google Analytics to track visitor volume and other statistics.
Reference data for street prices were obtained from the Researched Abuse, Diversion and Addiction Related Surveillance (RADARS) System Drug Diversion program, which collects data from approximately 280 police agencies in 49 US states on a quarterly basis. Methods of the RADARS System Drug Diversion Program, which is operated by the Center for Applied Research on Substance Use and Health Disparities, Nova Southeastern University (Miami, Florida), have been described previously [
Silk Road is an anonymous online marketplace structured as a Tor hidden service (see
Screenshot of StreetRx - features street price data on diverted pharmaceutical controlled substances for public health research purposes.
Screenshot of Silk Road - an anonymous online marketplace where drugs, fireworks, and stolen goods are sold.
The following drugs were initially considered for inclusion in the study: oral/sublingual dosing forms of buprenorphine, hydrocodone, hydromorphone, methadone, morphine, oxycodone, oxymorphone, tapentadol, tramadol, and transdermal patch formulations of fentanyl. Because only a small number of reports were available for tapentadol and transdermal fentanyl, these opioids were excluded from further analysis.
Geometric means and 95% confidence intervals of the price per milligram were calculated for each opioid. Correlation between systems was assessed by comparing opioid-specific means using the nonparametric Spearman rank correlation coefficient (rho), and tested with the null hypothesis that data from each pair of systems were independent with a two-tailed significance threshold of 0.05. Data management and analysis were performed using STATA version 12. In a preplanned secondary analysis, we used a standardized equianalgesic dosing conversion table [
Law enforcement data used in this study were reviewed by the Colorado Multiple Institutional Review Board (IRB), which also provides overall ethical oversight to the RADARS System. The Drug Diversion program is classified as exempt by the Nova Southeastern University IRB, as it does not constitute human subjects research.
Data from 954 StreetRx reports, 737 Drug Diversion reports, and 147 postings on Silk Road were analyzed. The most reports were received for oxycodone and hydrocodone in each system (
With the exception of morphine, there was no significant difference between the mean price per milligram of each opioid between the 3 data sources (
Street prices paid for different opioids generally followed the rank order of oral equianalgesic opioid potency clinically used for rotation of opioid analgesics (
Mean black market street prices and equianalgesic potency, US dollars per milligram, from online and law enforcement data sources, United States, 2012.
Drug | StreetRx Crowdsourcing | Drug Diversion Survey | Silk Road Marketplace | |||
|
n | Mean, US$ |
n | Mean, US$ |
n | Mean, US$ |
Hydromorphone | 75 | 3.29 (2.74-3.96) | 54 | 4.47 (3.57-5.59) | 14 | 3.55 (3.09-4.08) |
Buprenorphine | 34 | 2.13 (1.69-2.69) | 81 | 2.35 (1.97-2.80) | 12 | 2.58 (2.13-3.13) |
Oxymorphone | 38 | 1.57 (1.27-1.95) | 43 | 1.64 (1.29-2.10) | 6 | 1.58 (0.73-3.43) |
Methadone | 21 | 0.96 (0.71-1.29) | 81 | 1.16 (1.01-1.37) | 3 | 0.93 (0.65-1.34) |
Oxycodone | 454 | 0.97 (0.90-1.04) | 181 | 0.86 (0.78-0.93) | 43 | 0.99 (0.83-1.18) |
Hydrocodone | 228 | 0.81 (0.74-0.89) | 179 | 0.90 (0.84-0.97) | 46 | 0.97 (0.90-1.05) |
Morphine | 83 | 0.52 (0.40-0.68) | 81 | 0.67 (0.59-0.75)a | 16 | 0.42 (0.37-0.48)a |
Tramadol | 21 | 0.05 (0.03-0.07) | 37 | 0.09 (0.07-0.12) | 7 | 0.02 (0.01-0.03) |
aMorphine values differ between Drug Diversion Survey and Silk Road based on statistical test for possibility of random error (
Mean street prices from crowdsourced data, adjusted for potency relative to morphine, United States, 2012.
Drug | Crowdsourced Data from StreetRx | Predicted Relative Potency | Clinical Equianalgesic Potencyb | |
n | Mean, US$ (95% CI) | (95% CI)a | Milligrams | |
Hydromorphone | 75 | 3.29 (2.74-3.96) | 6.3 (5.8-6.8) | 4 |
Oxymorphone | 38 | 1.57 (1.27-1.95) | 3.0 (2.9-3.2) | 3 |
Methadone | 21 | 0.96 (0.71-1.29) | 1.8 (1.8-1.9) | 1.5 |
Oxycodone | 454 | 0.97 (0.90-1.04) | 1.9 (1.5-2.2) | 2 |
Hydrocodone | 228 | 0.81 (0.74-0.89) | 1.5 (1.3-1.8) | 1 |
Morphine | 83 | 0.52 (0.40-0.68) | 1.0 | 1 |
Tramadol | 21 | 0.05 (0.03-0.07) | 0.1 (0.07-0.13) | 0.3 |
aPredicted relative potency refers to the potency or desirability as predicted by the street price relative to morphine. It was calculated by standardizing the price per milligram for each opioid against that of morphine. These numbers do not distinguish oral from other routes of administration, nor take into account time-release mechanisms. They should not be used for clinical conversion.
bSource: United States Veterans Administration/Department of Defense Clinical Practice Guideline for the Management of Opioid Therapy for Chronic Pain, 2012.
Correlation between the data sources: StreetRx reports, Drug Diversion survey, and Silk Road postings.
Mean price per milligram of each opioid analgesic, between the data sources. Numbers at the bottom of each bar indicate sample size.
Data about the street price of diverted prescription opioid medications can be useful to policymakers and public health officials, but timely and accurate data are rarely available publicly. In this paper, we present findings of a national analysis of street price data for prescription opioid analgesics. Our findings show consistent prices per milligram across 3 independent sources, and that prices for different opioid active ingredients on the black market reflect their clinically established potency. We also demonstrate the feasibility of validating crowdsourced data in the absence of a “gold standard” and document the emergence of a hidden online marketplace where drugs are sold.
Our findings are among the first to document the consistency of prices per milligram among diverted opioid analgesics. Earlier researchers, referring to heroin and cocaine, noted that “the most striking characteristics of drug prices are their high levels and extreme variability over time and space” [
For the most part, previous research has focused on the prices and purity of illicitly manufactured drugs like heroin and cocaine [
In contrast to illicitly manufactured drugs, the different prescription opioids are nearly perfect “interchangeable goods”, from the economist’s perspective (but perhaps not the pharmaceutical industry’s); it is difficult to distinguish opioids of the same potency such as heroin (diacetylmorphine) and hydromorphone. This means that we cannot look at the prices of any single prescription opioid in isolation, but must also see what is happening with the prices of other opioid molecules. We found only 2 studies that examined street prices for opioid analgesics, neither of which focused on online sources. One study found a 10x linear association between the pharmacy price and the street price of prescription opioid analgesics in Vancouver, British Columbia [
More studies have examined Internet pharmacies. These studies concluded that the pharmacies (whether operating legally or illicitly) were found to be rarely used sources for diverted prescription drugs [
Websites designed for research-quality data collection via crowdsourcing and data mining are likely to cost less per report than traditional surveys and can be rapidly adapted to collect new information [
There are several limitations of this study that bear mentioning. Others have pointed out the need to take into account bulk purchasing when modeling prices of illicitly manufactured drugs [
Finally, we note that the use of equianalgesic ratios in clinical practice should be undertaken with caution, as should the interpretation of our results using these conversion numbers. In this analysis, we do not know if the opioids were diverted for self-medication, euphoria, or preventing withdrawal. The equianalgesic conversion factors were designed with opioid rotation for pain in mind, and the relative desirability for abuse or withdrawal prevention may be different. Various equianalgesic potency tables have been proposed [
Crowdsourcing and data mining are efficient ways to collect data about street prices in an era of Internet-based social networks. These data can inform pharmacoeconomic modeling and policy analysis, and may shed light on which new controlled pharmaceutical formulations have desirability relative to others when they hit the street. While this study represents an initial foray into collecting systematic economic data for modeling black markets for prescription drugs, the methodology could be extended in the future by connecting the data to health outcomes.
Institutional Review Board
National Drug Intelligence Center
Researched Abuse, Diversion, and Addiction-Related Surveillance System
The authors wish to thank Karen Lowitz for assistance in preparing this manuscript. This research was funded by the RADARS System (Denver, Colorado, USA).
StreetRx is entirely funded by the RADARS System (Denver, Colorado, USA), an independent nonprofit operation of the Rocky Mountain Poison and Drug Center (RMPDC), a division of Denver Health. StreetRx is operated under contract by Epidemico (Boston, Massachusetts, USA), a health data collection and analytics company. Authors of this paper include employees of the RADARS System and Epidemico. All datasets used in this publication are publicly available by contacting the RADARS System.