It’s bad enough that only a small fraction of individuals with substance use disorder treatments can access and receive treatment. But we also know less than we might about how they respond to a variety of medical treatments because they are routinely excluded form clinical trials.
People with psychiatric disorders are excluded from medical research to an unknown degree with unknown effects. We examined the prevalence of reported psychiatric exclusion criteria using a sample of 400 highly-cited randomized trials (2002-2010) across 20 common chronic disorders (6 psychiatric and 14 other medical disorders). […] Non-psychiatric conditions with high rates of reported psychiatric exclusion criteria included low back pain (75%), osteoarthritis (57%), COPD (55%), and diabetes (55%). The most commonly reported type of psychiatric exclusion criteria were those related to substance use disorders (reported in 48% of trials reporting at least one psychiatric exclusion criteria). General psychiatric exclusions (e.g., “any serious psychiatric disorder”) were also prevalent (38% of trials). Psychiatric disorder trials were more likely than other medical disorder trials to report each specific type of psychiatric exclusion (p’s < .001). […] Clinical trials greatly influence state-of-the-art medical care, yet individuals with psychiatric disorders are often actively excluded from these trials. This pattern of exclusion represents an under-recognized and worrisome cause of health inequity. Further attention should be paid to how individuals with psychiatric disorders can be safely included in medical research to address this important clinical and social justice issue.
That’s from the abstract of a paper by Keith Humphreys, Janet Blodgett, and Laura Roberts. I have not read the paper, so perhaps it makes the following point. If patients with these conditions, including substance use disorder, cannot be included in some trials for justifiable reasons (which is plausible, but I have not thought it through), one approach to studying their treatment outcomes is to rely on observational studies (yes, they have their limitations).
But, there’s a massive problem with that as well and regular readers can guess what it is. Today researchers can only obtain the key Medicare and Medicaid data they typically rely on for observational work that has been scrubbed of all substance use disorder-related records. These include those with principal diagnoses of such disorders, as well as those with a secondary diagnosis of one. That means even observational studies with Medicare and Medicaid data of low back pain, osteoarthritis, COPD, and diabetes cannot include the very patients that are also frequently excluded from randomized trials.
I agree with the authors that this, in total, is “a worrisome cause of health inequity.”