Researchers in the United States have set out plans for a major review into how chronic pain and substance use are connected, hoping to answer questions that have gone largely unexamined for more than a decade.

The protocol, published in PLOS One and led by Andrew H. Rogers of the University at Buffalo alongside colleagues from Binghamton University, the University of Kansas, Mayo Clinic Arizona, Arizona State University and Johns Hopkins School of Medicine, outlines a systematic review and meta analysis that will pull together existing research on nicotine, alcohol and cannabis use disorders among adults living with chronic pain.

Why chronic pain and substance use keep turning up together

Chronic pain, defined as pain lasting three months or longer, is thought to affect somewhere between one fifth and one third of adults worldwide. Beyond the physical toll, it carries a huge financial burden, with medical, psychiatric and economic costs estimated at more than one trillion dollars a year in the United States alone.

What has drawn researchers’ attention is the relationship between chronic pain and substance use. Pain can act as a powerful motivator for using nicotine, alcohol or cannabis, often as a way of self managing symptoms, while ongoing substance use can end up making pain worse. It is a two way relationship that the research team describes as bidirectional, with each factor capable of feeding into the other.

A gap left by decades of focus on opioids

Most of the research attention on substance use in people with chronic pain has gone to opioids, largely because prescriptions for pain were seen as a key driver of the wider opioid crisis. Studies have consistently shown higher rates of opioid use disorder among people with chronic pain compared to those without it, and nearly half of people being treated for opioid use disorder also meet the criteria for chronic pain themselves.

Far less is known about nicotine, alcohol and cannabis, even though they are used more widely. The last major attempt to measure this, a review published back in 2011, found that between three and forty eight percent of adults with chronic pain met the criteria for a substance use disorder, but that figure lumped in opioid use disorder too and left nicotine out of the picture entirely. More than ten years on, the research team argues that gap still has not been properly filled, and the wide range in that older estimate shows just how unclear the true picture remains.

How the new review will work

The team has registered its protocol with the International Prospective Register of Systematic Reviews and will search five major databases, including PubMed, Embase, Web of Science, CINAHL and PsycINFO, for relevant studies. Two independent reviewers will screen titles and abstracts before moving to full text review, with a third reviewer brought in to settle any disagreements.

Once the eligible studies have been identified, researchers will pull out details on prevalence rates for nicotine, alcohol and cannabis use disorders, along with problematic use that falls short of a formal diagnosis but can still carry long term health consequences. The results will be combined using statistical modelling to produce overall prevalence estimates, and the team plans to look at how those rates vary by factors such as study location, pain condition, biological sex and the type of substance product used. Data extraction and results are expected to follow within twelve months of the searches being completed.

What it could mean for patients and services

The team behind the review believes the findings could shape how chronic pain and substance use are handled at the clinical front line. If prevalence rates turn out to be as high as some existing data suggests, it could support wider use of validated screening tools for substance use disorders within pain treatment settings, along with better access to brief interventions or onward referral when it is needed.

Beyond individual clinics, the researchers point to potential benefits for policy makers too, including more informed resource allocation and the development of integrated care models that address chronic pain and substance use disorders together, rather than treating them as separate issues.

Limitations the team has flagged

The researchers have been upfront about the limits of their approach. Because of funding restrictions, only studies published in English will be fully included, which the team acknowledges could underrepresent findings from low and middle income countries and skew the overall picture of substance use disorders in chronic pain globally. They also expect to find considerable variation in how studies define and measure problematic substance use, which may limit how directly some of the pooled results can be compared or generalised.

Even so, the researchers argue that a clearer, more accurate picture of chronic pain and substance use is long overdue, and one that could ultimately help shape how both conditions are recognised, prevented and treated together in the years ahead.

Source: dbrecoveryresources