Smaller, cause-specific opioid prescriptions after emergency department visits for acute pain could provide adequate pain management and reduce the risk of misuse of unused opioid pills, according to new research.
In a prospective study in Canada, about two thirds of opioid tablets remained unused at 2 weeks post discharge, and this amount varied according to the cause of acute pain.
"As higher quantities of prescribed opioids are associated with higher quantities of consumed opioids, it is important to adapt opioid prescription practices to patients' analgesic needs for specific acute pain conditions while minimizing the number of unused opioid tablets that can be diverted or misused," lead author Raoul Daoust, MD, a clinical professor of family medicine and emergency medicine at the University of Montreal and a staff emergency physician at Sacré-Cœur de Montréal Hospital in Montreal, Quebec, Canada, told Medscape Medical News.
"Clinicians choosing to prescribe opioids could adapt the quantity of prescribed opioids to the specific painful condition based on the quantity of morphine 5-mg tablet equivalents required to meet the needs of 80% of patients described in our results," he said.
The study was published online on July 15, 2024, in The Canadian Medical Association Journal.
Opioid Use Patterns
Opioid overdose has increased in Canada in recent years. It killed more than 7500 people in 2021, and overdoses are projected to increase until 2025, the authors wrote. About half of patients with opioid use disorder were first exposed through a legitimate prescription, and 20% were prescribed in the emergency department. However, pills are often left unused and rarely stored or disposed of properly, which can lead to misuse later.
Daoust and colleagues from the Network of Canadian Emergency Researchers conducted a prospective cohort study at seven emergency departments in Ontario and Quebec to understand the optimal quantity of prescription opioids required to control pain after certain emergency department visits for acute pain. They also wanted to determine the quantity of unused opioids available for misuse and how to reduce it.
The study included 2240 adults who experienced an acute pain condition for < 2 weeks and received an opioid prescription from an emergency department between May 2019 and January 2023. Participants had an average age of 51 years and average pain intensity score at triage of 7.1. About 48% were women, 77% were White individuals, and 86% preferred speaking French.
The most common pain conditions included fractures, renal colic, back pain, neck pain, abdominal pain, other musculoskeletal pain (such as contusion, bursitis, strain, muscle or tendon tear, sprain, dislocation, or tendinitis), and uncategorized pain conditions (such as abscess, burn, or tooth pain).
Participants completed a 14-day electronic pain medication diary that asked about the quantities, doses, and names of analgesics, including over-the-counter medications. In phone interviews, participants discussed whether they filled their initial prescriptions, how many pills they took, and if they filled any new prescriptions.
Because of the different potencies and dosages of various opioids, the research team converted the prescriptions into the equivalent of 5-mg morphine tablets. For instance, one morphine tablet was considered equipotent to 3.33 mg of oxycodone, 1.25 mg of hydromorphone, 33.3 mg of codeine, and 50 mg of tramadol.
Overall, 93% of participants filled their initial opioid prescription during the 2-week follow-up period, and the median number of prescribed 5-mg morphine tablet equivalents was 16, which was similar across all pain categories.
In general, opioid consumption was low, and half of patients took fewer than five tablets. However, opioid consumption varied significantly by the type of pain condition, ranging from a median of two tablets for renal colic or abdominal pain to eight tablets for back pain and nine tablets for fractures. Patients with fractures or back pain were more likely to fill additional opioid prescriptions.
Opioid and over-the-counter use varied by time, with 67% of participants consuming opioids on the first day, 62% taking acetaminophen, and 44% taking nonsteroidal anti-inflammatory drugs (NSAIDs). By day 14, 12% consumed opioids, 30% took acetaminophen, and 16% took NSAIDs.
After the 2-week period, about 63% of prescriptions weren't consumed, leaving more than 26,000 unused tablets, the research team wrote.
Optimizing Opioid Prescriptions
Based on estimates to alleviate pain in 80% of patients for 2 weeks, the authors calculated opioid requirements of eight tablets for renal colic, abdominal pain, or uncategorized pain conditions; 17 tablets for neck pain and other musculoskeletal pain; 21 tablets for back pain; and 24 tablets for fractures. The numbers mirror similar findings from a study in the United States, which calculated 95% quantities by diagnosis, with about nine tablets for renal colic, 12 for musculoskeletal injuries, and 15 for fractures or dislocation.
"These data help to underscore that opioid prescriptions for acute pain are not a one-size-fits-all situation," said Danielle McCarthy, MD, associate professor of emergency medicine at Northwestern University's Feinberg School of Medicine in Chicago, who coauthored the US study.
"Ideally, additional studies would confirm our data in more diverse populations, eventually informing a more evidence-driven approach to acute prescribing limits," she said.
To further reduce misuse, Daoust and colleagues suggested adding an expiration date for use, such as 14 days. In addition, since half of participants took smaller amounts than prescribed, pharmacists could provide half of the suggested quantities — or partition prescriptions — to further reduce unused opioids available for misuse. In the United States, for instance, several states limit opioid prescriptions to 7 days after an emergency department visit, so 7-day estimates could be beneficial as well, the authors wrote.
Acute prescribing guidelines should also consider the wide range of patient responses to opioids, subjective pain experiences, and patient comorbidities, McCarthy said.
"Importantly, any change in guidelines will require thoughtful consideration of the impact on individual physicians and patients, as well as the more collective perspective of overall public health," she said. "This approach must include a relative prioritization of the competing goals of minimizing excess opioid exposure while ensuring adequate pain relief, as well as a consensus definition of the optimal target for population-level quantity-based guidelines (meeting the needs of 80% vs 95% or some other target)."
The study was funded by the Canadian Institutes of Health Research. Daoust and McCarthy reported no relevant financial relationships.
Carolyn Crist is a health and medical journalist who reports on the latest studies for Medscape Medical News, MDedge, and WebMD.