The exclusion of people with psychiatric disorders from medical research

• Coded psychiatric exclusion criteria in 400 highly cited trials across 20 disorders.
• Psychiatric exclusion criteria were employed in at least half of clinical trials.
• Psychiatric treatment trials were most likely to report psychiatric exclusion.
• Substance use disorder exclusion criteria were most common.

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). Two coders rated the presence of psychiatric exclusion criteria for each trial. Half of all trials (and 84% of psychiatric disorder treatment trials) reported possible or definite psychiatric exclusion criteria, with significant variation across disorders (p < .001). 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). Because published clinical trial reports do not always fully describe exclusion criteria, this study's estimates of the prevalence of psychiatric exclusion criteria are conservative. 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.