The contribution of opioid analgesic use to the initiation of antidepressant medication in the older adult population

• Author / Creator

  Palakkamanil, Marla

• The purpose of this thesis was to examine the incidence of antidepressant use following opioid initiation. This study relied on the exclusive use of outpatient community dispensations for all prescriptions. The cohort was restricted to Alberta residents aged 55 to 80, enrolled in the Alberta Health Insurance plan for at least one calendar year, and excluded cancer-related pain treatment. Patients were included if their first opioid dispensation occurred between January 1st, 2010, and December 31st, 2014, and the first antidepressant dispensation occurred within one year after the first opioid dispensation. A three-month washout period was applied as a conservative time frame to remove prevalent cases of opioid analgesic use. The end of the follow-up was a new antidepressant dispensation in a previously (12-month) antidepressant-naïve patient, up until one year from the first opioid dispensation or the end of the study. These criteria set up the temporal relationship so that incident opioid analgesic use occurred in patients without current antidepressant use and preceded any new-onset psychiatric comorbidity or exacerbation of an existing morbidity.

  The cohort consisted of a population of 408,862. The total number of people between 2010 and 2014 who were dispensed an antidepressant within one year of starting an opioid was 39,650, or 9.7% of the cohort population. Overall, the incidence proportion of antidepressants after the first opioid dispensation decreased by 42.8% across the study period from 2010 to 2014. Compared to men, women had a consistently higher incidence proportion of antidepressants dispensed each year. Out of all the people prescribed an antidepressant after first opioid dispensation having no recent history of antidepressant use or psychiatric diagnosis, 24.43% were being treated for new-onset depression and 19.15% for new-onset anxiety. The declining incidence proportion of antidepressants suggests the possibility of a saturation effect: as prevalent dispensation of opioids increases, fewer unexposed patients are available for incident opioid dispensations and subsequent incident antidepressant dispensations. The results demonstrate that in those people free of opioid and antidepressant use in the year prior to initiation of opioid treatment, subsequent antidepressant use is most likely attributable to treatment of depression or anxiety as compared to other psychiatric comorbidities.

  A risk factor analysis was conducted to enable a better understanding of those individuals who are at a higher risk than others for antidepressant initiation after first opioid dispensation. The risk of incident antidepressant dispensation within one year of opioid initiation increases with high dose opioids (>90 MEQ). Female sex and prior history of depression are also found to predict subsequent antidepressant initiation. Rural residence was not found to have a statistically significant association with antidepressant initiation after opioid dispensation.

  The information presented in this study adds to the accumulating evidence regarding a link between opioid analgesic use and the risk of depression. However, this research is unique in that it demonstrates an association between opioid analgesic use and subsequent initiation of antidepressants in general among older adults. Rather than restricting the study to focus on specific indications of opioid analgesic use such as chronic pain, this study approached the data from a wider lens by investigating the correlation between opioid and antidepressant medication use. There is substantial likelihood that opioid therapy will continue to present clinical challenges given Canada’s aging population. Opioid prescribing should be coupled with careful screening and treatment of emerging mental health disorders. Screening tools for depression (Patient Health Questionnaire (PHQ)-2 and PHQ-9) and anxiety (Generalized Anxiety Disorder Questionnaire (GAD-Q-IV) and GAD-7) can be programmed into electronic medical record systems to prompt screening prior to opioid initiation. Additionally, understanding the risks associated with antidepressant initiation following first opioid dispensation will enable prescribers to target early intervention efforts and screening tools to mitigate harm and prevent mental health issues from arising in the future. Screening of psychiatric disorders for all patients should take place prior to an opioid trial. For those patients beginning ongoing opioid treatment, antidepressant prophylaxis or treatment of depression should be considered. Future research should explore whether the coadministration of antidepressants and opioids serves to prevent incident psychiatric disorders in those patients initiated on opioids.

• Subjects / Keywords

  • opioids and antidepressants
  • opioids and depression
  • opioids and psychiatric illness

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-4edp-j421

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.