RESEARCH WEEKLY: Chronic Pain among Individuals with Serious Mental Illness
Individuals with serious mental illness are prescribed opioids at rates very different from the general population, even though they are at more risk to have issues with these highly addictive drugs.
The prescription of opioids for chronic pain across major depressive disorder, bipolar disorder and schizophrenia differ greatly, according to new research published earlier this year. While major depressive disorder and bipolar disorder lead to higher rates of chronic pain and opioid prescriptions, people with schizophrenia are less likely to receive a chronic pain diagnosis and opioid prescription. This has important implications for opioid use disorders as well as pain management.
The relationship between pain and schizophrenia is complicated, according to the study authors. They found that even though people with schizophrenia have an increased risk of developing conditions associated with chronic pain, patients appear less likely to be diagnosed with what is called chronic non-cancer pain. This further translates into lower rates of opioid prescriptions for people with schizophrenia compared to other serious mental illnesses. Researchers suggest this disparity highlights an opportunity to incorporate pain management care into the spectrum of mental health services.
Chronic Non-Cancer Pain and Opioid Prescriptions
The diagnosis of chronic non-cancer pain includes a variety of painful conditions. Researchers identified 11 pain diagnostic groups ranging from back and neck pain to general and non-specific pain. Participants were found to have chronic non-cancer pain if they reported two or more of these diagnoses during the research period.
Opioid prescriptions for chronic pain were defined in the study as having prescriptions for at least 70 days of any 90-day period or having more than six prescriptions for opioids in one year. This would eliminate any use of opioids for acute or non-chronic pain in studied individuals. Additionally, individuals with a cancer diagnosis were excluded from this study.
Methods
Researchers accessed ten Mental Health Research Network sites’ health system data throughout the United States. Included in the study were records for more than 65,000 major depressive disorder cases, 38,000 bipolar disorder cases, and 12,000 schizophrenia cases. They similarly tracked individuals without a mental illness diagnosis but were similar in age, sex, and insurance status. In total, researchers assessed pain and opioid use in more than 370,000 individuals.
Following the identification of cases, researchers calculated an odds ratio for both a chronic pain diagnosis and opioid prescription, comparing people with a serious mental illness to the general population. The results are the following:
- People with depression were 1.9 times more likely to receive a chronic pain diagnosis. They were 2.6 times more likely to receive an opioid prescription.
- People with bipolar disorder were 1.7 times more likely to receive a chronic pain diagnosis. They were 2.1 times more likely to receive an opioid prescription.
- People with schizophrenia were less likely (0.8 times as likely) to receive a chronic pain diagnosis. They received opioid prescriptions at the same rate as the general population.
Schizophrenia and Pain
The study authors discussed possible reasons for the small number of cases of chronic pain in people with schizophrenia and suggested several possible theories. First, some antipsychotic medications appear to have pain-reducing effects on their own. However, the results indicate both individuals with and without prescriptions for antipsychotic medications appear to have higher pain tolerance.
Second, many researchers have suggested that there is an under-diagnosis of chronic pain in people with schizophrenia due to communication barriers. It is possible that people with schizophrenia have difficulty communicating their pain, or choose not to tell health care providers, out of fear of hospitalization.
Regardless of the cause, the researchers concluded that schizophrenia leads to a distorted experience of pain. This means that although researchers do not fully understand the relationship between schizophrenia and pain, there is certainly a unique interaction in people with schizophrenia when experiencing pain that makes it different from how people without schizophrenia experience pain.
Serious Mental Illness and Substance Abuse
The study authors emphasized that those with mood disorders are more likely to be diagnosed with an opioid use disorder than the general population, making the increased prescriptions for opioids for chronic pain especially alarming. There is an identified need for mental health practitioners to be involved with pain management for patients, they argue.
Since mental illness is already a known risk factor for opioid related use disorders, caution should be taken in the use of opioids in the population with serious mental illness. The authors pointed to the Canadian Medial Association’s recommendation to avoid opioid prescriptions for people with serious mental illness. However, the American Medical Association does not have a similar recommendation at this time.
