A Saint Louis University researcher has received a grant to study the pathways from chronic prescription opioid use to new onset mood disorder. Jeffrey Scherrer, Ph.D., a professor in Family and Community Medicine, received $3,254,485 from the National Institute on Drug Abuse of the National Institutes of Health (NIH).
"We hope our findings will inform pain management and safe opioid prescribing for patients with chronic, non-cancer pain," Scherrer said.
The grant will build upon Scherrer's previous findings that indicate a new period of opioid analgesic use lasting beyond 30 days is associated with increased risk of new-onset depression.
In several previous studies controlling for pain, researchers found long-term (more than 90 days) opioid analgesic use is associated with increased risk for depression and impairs depression treatment and recovery.
This project collects data from 1,500 patients using prescription opioids to identify factors that may increase the risk of opioid-related depression. Data collection will occur at three sites across the United States. The study will collect baseline, six month and 12-month measures of pain, functioning, psychiatric and substance abuse disorders, sleep, social support and quality of life. Participants will also be asked to complete a brief monthly survey to measure rapid changes in pain, opioid use and depression.
"We found that patients with depression were 22 percent more likely to develop treatment-resistant depression with opioid use of 31-90 days and 49 percent more likely if they used opioids for more than 90 days," Scherrer said. "The consistency of our findings, replication in VA and in private sector patients and rigorous control for pain support the theory that opioid analgesic use is likely a risk factor for depression."
In multiple studies with robust control for confounding, including pain severity, longer opioid analgesic use predicted new onset depression in patients who were on average 50 years old with no recent history of depression, no evidence of opioid misuse and no recent history of opioid analgesic use.
A prospective study is needed to advance research, Scherrer says, due in part to the limitations of medical record data. The records lack lifetime histories of mood disorders and other risk factors, including substance abuse disorder and trauma exposure. The records also fail to provide good measures of functional impairment, sleep quality and social support.
"The electronic medical records do not contain prospective data on the sequence of pain, opioid analgesic use and depression symptom development," Scherrer said. "Our key objectives are first to determine if patients with a prior history of depression are most likely to develop a new episode following prescription opioid use."
Scherrer also wants to determine if opioid-related adverse outcomes, such as opioid misuse and sleep apnea that occur after long-term opioid use subsequently contribute to new onset depression.
"Next we want to expand on the limited knowledge about depression that was available in the medical record," he said. "Our goal is to determine if chronic opioid use leads to major depressive episodes or to symptom clusters that look like depression, such as anhedonia, vital exhaustion, apathy and dysthymia."
Lastly, the study will seek to determine the characteristics of depression most strongly related to whether patients with mild depression have the same risk for misuse as those with severe depression and comorbid anxiety disorders.