Patients who increased doses of opioid medicines to manage chronic pain were more likely to experience an increase in depression, according to a study published in the February issue of Pain.
Lead study author Jeffrey Scherrer, PhD, associate professor for family and community medicine at Saint Louis University, Saint Louis, Mo., and his colleagues studied questionnaires from 355 patients from 9 practices in the Residency Research Network of Texas who reported chronic low back pain initially and at 1-year and 2-year follow ups. The study expands the authors' findings in a previous study of Veterans Administration (VA) patients.
Survey respondents were 72.4% female, older than aged 46 years (75.2%) and mostly of Hispanic or African-American descent (57.5%). The patients reported the number of years they had been experience chronic pain.
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Scherrer"Better understanding of temporal relationship between opioids and depression and the dose of opioids that places patients at risk for depression may inform prescribing and pain management and improve outcomes for patients with chronic, non-cancer pain," the study found.
“We observed that patients who increased their morphine equivalent dose to >50 mg per day compared to patients who remained non-users or 1-mg to 50-mg users, were 2.6 times more likely to experience an increase in depression over time,” Scherrer said.
Previous research had found depression to be linked with patients' opioid use, but this study has identified the association between an increase in opioid use and an increase in depression.
Contributing factors for cases of new-onset depression, according to this study and previous research conducted by Scherrer, may include both the amount of daily morphine exposure and the duration of exposure. The study calls for further study to determine whether patients are at-risk due to past episodes of depression or recent depressive symptoms.
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Scherrer noted that since the acceptance of the paper, his team has continued to analyze a large VA medical record database.
“After this study, we analyzed a large VA medical record data base and found that duration of use was a stronger predictor of new onset depression compared to maximum opioid dose,” Scherrer said. “Therefore, with the published study results and our yet to be published findings, we conclude that the higher opioid dose and risk of depression could represent patients who used opioids for a longer period of time during which they increased dose.”
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Opioid therapy has side effects and consequences, Scherrer said. “If chronic opioid use leads to depression, then managed care should support routine screening for depression during opioid therapy as well as treatment of depression for patients requiring opioids for pain. Our results also point out the value of collaborative care. In this case, patients receiving opioid therapy may have better outcomes when patients have access to co-located mental health specialty care to detect and manage depression.
“Providers need to be aware of the risk of depression associated with longterm opioid use and consider opioids, not just pain, when patients report depressed mood,” Scherrer added.