As the number of long-term opioid prescriptions for U.S. adults has risen, older adults – who make up a quarter of patients prescribed opioids for more than 90 days – have experienced increased rates of adverse outcomes. Addiction, misuse, and overdose have all risen in the population of older adults, alongside the increase in long-term opioid prescriptions.
Although chronic pain is prevalent in older adults, appropriate medication treatment is challenging for this population due to an elevated risk of adverse events, as well as polypharmacy – the use of multiple pharmacies to obtain medications. Older adults with dementia may be especially vulnerable to adverse events associated with opioids, given the inherent difficulty in assessing and treating pain in this vulnerable population.
A team of researchers from the University of Kentucky College of Public Health, College of Pharmacy, and Sanders-Brown Center on Aging investigated patterns of longitudinal opioid utilization in older adults, using group-based trajectory models to identify potential predictors of chronic opioid use. The results of that study appear in PLOS One. Ms. GYeon Oh, epidemiology and biostatistics PhD student at the College of Public Health, is the first author of “Patterns and predictors of chronic opioid use in older adults: A retrospective cohort study”. Co-authors are Dr. Erin Abner, associate professor of epidemiology and biostatistics in the College of Public Health; Dr. David Fardo, associate professor of biostatistics in the College of Public Health; Dr. Daniela Moga, associate professor of pharmacy practice and science in the College of Pharmacy with a joint appointment as associate professor of epidemiology in the College of Public Health; and Dr. Patricia R. Freeman, associate professor of pharmacy practice and science in the College of Pharmacy.
Prior studies produced recommendations to deploy increased monitoring to minimize the risks of opioids in older adults, yet lacked detailed guidance on opioid prescribing. Noting that studying the characteristics associated with opioid use in older adults can help identify factors that could improve risk-benefit assessment and prevent inappropriate use, this study investigated the patterns of opioid analgesics use, and identified predictors of inclusion in different use trajectories over 10 years of follow-up in older adults.
The Kentucky investigators drew study data from the National Alzheimer’s Coordinating Center (NACC) Uniform Data Set (UDS), which comprises participants enrolled in longitudinal studies at National Institute on Aging-funded Alzheimer’s Disease Centers (ADC) throughout the U.S. Participants included subjects with cognitive status ranging from normal to dementia that are recruited through clinician referral, self-referral by patients or family members, active recruitment, and volunteers.
In the NACC UDS, information was provided by each participant and/or their caregiver/legally authorized representative, and was based on each participant’s reported medication use within two weeks of each study visit. In assessing opioid use, opioid medications used as antitussives were not considered. Participants were considered to be “any opioid” users if they reported use of any opioid analgesic medications, and “strong opioid” users were defined among any opioid users if they reported use of opioid analgesics stronger than or equal to the potency of morphine (e.g., buprenorphine, fentanyl, hydrocodone, hydromorphone, methadone, morphine, opium, oxycodone, oxymorphone).
Baseline characteristics of interest, including demographic and self-reported medical information, were recorded at each participant’s initial UDS visit. Self-reported medical history information included current smoking, history of alcohol abuse, and other abused substances; hypertension, diabetes, urinary incontinence, and cardiovascular conditions. Medication information included number of medications reported; use of nonsteroidal anti-inflammatory medications (NSAIDs), antidepressants, antipsychotics, and anxiolytic, sedative, or hypnotic agents. Clinician-determined agitation and cognitive were also included in the analysis. Of 13,059 participants included in the study, the majority were female, white, and lived in private dwellings. At their initial UDS visit, 3.8 percent of participants were classed as “any opioid” users, with 2.2 percent classed as users of “heavy opioids”.
Group-based trajectory models (GBTM) were used to identify participants with similar longitudinal patterns of opioid analgesic use. The study identified four longitudinal trends — minimal-users, incident chronic-users, discontinuing-users, and prevalent chronic-users — for use of both “any” and “strong” opioids.
The authors found that participants who were older, female, black, residing in independent group living or care facilities, or taking antidepressant agents were more likely to be chronic-users compared to minimal-users of “any” or “strong” opioids. These results are consistent with previous studies that reported that older adults and women experience pain more frequently than younger adults and men, and that older women have a higher prevalence of long-term opioid use. Also, previous studies have shown that long-term opioid use is highly prevalent in nursing home residents compared to people in a community setting, and having depression was associated with long-term opioid use in older adults.
The investigators also found that taking anxiolytic, sedative, or hypnotic agents (including barbiturates and benzodiazepines) was significantly associated with prevalent chronic-use in both the “any opioid” and “strong opioid” user groups compared to minimal-use. They also observed that the prevalence of taking benzodiazepines was higher in prevalent chronic-users than in minimal-users In a recent study including adult participants of the National Health and Nutrition Examination Survey (NHANES), long-term use of opioids was associated with concurrent benzodiazepine use. Considering the overdose risk of co-prescribing benzodiazepine and opioids, the CDC guidelines suggest avoiding the use of opioids and benzodiazepines together. Further studies are needed to investigate the effect of using opioids and benzodiazepines together on opioid-related adverse outcomes in older adults.
The Kentucky team further found that patients with dementia were less likely to become chronic users of either “any” or “strong” opioids compared to non-users. This trend might be due to inherent difficulties in assessing and treating pain in these patients, as well as potential concerns about the added burden of cognitive impairment and risk of other adverse events from opioids. Given the concern about serious problems (e.g., depression, anxiety, and agitation) that could result from under-treating pain in older adults, future studies are required to thoroughly address the patterns of opioid use in patients with dementia.
Reporting a higher number of medications was positively associated with prevalent chronic-use of both “any opioid” and “strong opioids”; however, with respect to incident chronic-use, the results showed that participants with higher number of medications were less likely to be incident chronic-users compared to discontinuing-users or minimal-users. Since ADC participants may be more likely to receive medical care than the general population, there is a possibility that the participants with polypharmacy were monitored more closely with regard to newly prescribed opioids. Thus, this result may not be generalizable to all older adults in the U.S. Neither comorbidities nor number of medications significantly predicted prevalent chronic-use vs. discontinuing use.
Overall, the study showed that potentially inappropriate opioid use was disproportionately prevalent among vulnerable NACC participants (i.e., those of older age, with multiple comorbidities, and multiple pharmacies). Further studies are required to thoroughly address the risk and benefit of using opioids in older adults, and it is essential to provide evidence-based guidelines for opioid use in this population.