Would Drug Legalization Reduce Overdoses?

By Roger Chriss, PNN Columnist

As the overdose crisis worsens, public health data and biostatistics become more important. Debates about opioid prescribing and drug legalization often center on two key concepts: incidence and prevalence as applied to drug use, substance use disorder (SUD) and overdoses.

Brandeis University researcher Andrew Kolodny, MD, recently argued against drug legalization on Twitter.

“Some critics of reducing Rx opioids don't believe that repeated use of highly addictive drugs cause addiction and/or they believe all drugs, including heroin & cocaine should be available over the counter. They don't believe that easy access can increase prevalence of SUD,” said Kolodny, who founded Physicians for Responsible Opioid Prescribing (PROP), an anti-opioid activist group.

Conversely, Columbia University professor Carl Hart, the author of “Drug Use for Grown-Ups,” believes legalizing recreational drugs would help reduce overdoses by making the drug supply safer.

“A large proportion of these deaths are caused by adulterated substances purchased on the illicit market. A regulated market, with uniform quality standards, would virtually put an end to contaminated drug consumption and greatly reduce fatal accidental drug overdoses,” Hart told Columbia Magazine.

Both claims hinge on a proper understanding of incidence and prevalence. In epidemiology, incidence is the rate of new-onset diagnosis of a medical condition. It is measured over a given period of time -- typically a year -- though sometimes the time period is shortened to a week for an urgent problem, such as a viral pathogen like the coronavirus.

By contrast, prevalence measures the total number of people in a population who have a specific medical condition. For prevalence, the duration of the condition is important. For an infectious disease, it may be brief. But for cancer, SUD and many other chronic conditions, it may last a lifetime.

For instance, the incidence of opioid use disorder (OUD) among people who are on long-term opioid therapy is 8-12%, according to the National Institutes of Health. But unlike claims frequently made by PROP, only a small fraction of patients who abuse prescription opioids start using heroin, less than 4% over a five-year period. So, making a clear distinction between OUD involving prescription opioids versus heroin becomes important.

The prevalence of OUD is a cumulative total of all people with OUD over time. This is because OUD and other substance use disorder diagnoses are lifetime diagnoses that remain on a person’s medical records forever. When we count people with OUD, we are counting everyone ever diagnosed with the condition, though in practice sometimes the OUD diagnosis is dropped due to administrative error, poor record-keeping or deliberate obfuscation.

This means that OUD prevalence can go up over time even when the incidence of OUD is going down. In fact, that is what is happening at present.

A recent report from the Substance Abuse and Mental Health Services Association showed modest declines for both prescription opioid misuse and heroin use. This came at a time when U.S. drug deaths were rising, fueled primarily by overdoses involving illicit fentanyl.

These counterintuitive trends make for intense debate about the success or failure of the 2016 CDC opioid guideline and state laws restricting prescription opioid use. A recent study from Indiana University concluded that limits on legal opioid prescribing may have actually driven more people to illicit drugs.

"Our work reveals the unintended and negative consequences of policies designed to reduce the supply of opioids in the population for overdose. We believe that policy goals should be shifted from easy solutions such as dose reduction to more difficult fundamental ones, focusing on improving social conditions that create demand for opioids and other illicit drugs," said co-author Brea Perry, PhD, a professor of sociology at Indiana University.

Even if drug legalization were to reduce drug risks, an increase in the number of drug users could lead to more harms. For instance, if an illicit drug harms 10% of users and there are 1 million users, that results in 100,000 people harmed. If that drug is then legalized and made safer, harming only 1% of users, that seems like an improvement. But if the number of users rises to 15 million, then 150,000 people would be harmed.

Since we don’t know how these numbers would change under a legalized drug regime, any claims about changes in incidence or prevalence are speculative at best.

What is counted and how it is expressed are very important in debates about the role of prescription opioids or drugs in general in SUD and overdose deaths. A failure to be specific about methodology or using data that is not well-founded can result in specious or even deceptive claims. And counterintuitive results are possible, as we are seeing at present in the ever-evolving overdose crisis.

Roger Chriss lives with Ehlers Danlos syndrome and is a proud member of the Ehlers-Danlos Society. Roger is a technical consultant in Washington state, where he specializes in mathematics and research.