Author: Michael Vlessides
A secondary analysis of a prospective cohort study has concluded that total knee arthroplasty (TKA) patients with higher baseline pain catastrophizing scores consume more opioids than their counterparts who catastrophize to a lesser degree.
The researchers hope their findings prove to be a springboard for early interventions that may prevent opioid overexposure among these individuals.
As Arissa Torrie, MD, MHS, a resident at the Johns Hopkins University School of Medicine, in Baltimore, discussed with Anesthesiology News, previous research has demonstrated that acute postoperative pain varies based on a variety of physiologic, psychosocial and sociocultural factors. Nevertheless, opioid prescribing rarely considers these interindividual differences, as most patients are given standard prescriptions.
In the wake of the opioid crisis, however, personalized opioid prescribing after TKA may help to both improve postoperative pain management and minimize patient exposure to the agents.
To help characterize the multidimensional factors that influence opioid use in the first 72 hours after TKA, Dr. Torrie and her colleagues analyzed data from a prospective, multicenter trial of individuals with knee osteoarthritis undergoing TKA. As part of that study, patients completed preoperative questionnaires aimed at assessing a variety of factors, including pain (Brief Pain Inventory), opioid consumption, nonopioid pain medications, catastrophizing (Pain Catastrophizing Scale), depression and anxiety.
Perioperative opioid consumption, nonopioid pain medication, pain, ASA ratings and surgical duration were extracted from the patients’ medical records.
The primary objective of the analysis was to evaluate the contribution of baseline catastrophizing levels to postoperative opioid consumption (morphine milligram equivalents [MME]) after controlling for demographic, clinical and psychosocial variables.
Presenting at the 2019 annual meeting of the American Society of Anesthesiologists (abstract F2059), Dr. Torrie explained that 248 patients were included in the analysis; postoperative MME data were available for 215. The patients’ mean age was 64.9±8.1 years; 58% were women and 90% were non-Hispanic white. The mean length of stay was 2.3 days.
Demographic variables accounted for 5% of observed variance in postoperative MME among patients. Clinical variables, on the other hand, accounted for an additional 31%. Psychosocial variables were insignificant to the model.
After performing hierarchical multiple regression with average postoperative MME as the dependent variable, the final model revealed that only higher concurrent pain ratings (beta=0.4; P<0.001) and level of pain catastrophizing (beta=0.24; P=0.008) were statistically significant predictors.
The study also found that for every 1-point increase in postoperative pain, MME increased 8.1. Similarly, for each 1-point increase in Pain Catastrophizing Scale score, MME increased 0.5.
No difference was found, however, between the high- and low-catastrophizing groups with respect to intraoperative opioid requirements.
“What was interesting was that when we controlled for pain and looked at opioid consumption in the PACU and on postoperative day 0, that’s when they had higher opioid requirements,” Dr. Torrie explained.
“Even though we controlled for pain, it’s the psychological factor of pain catastrophizing that still sees them wanting more opioids, because they perceive the need,” she added.
Searching for the Answers
The research was limited by the fact that psychological characteristics—including catastrophizing—were only measured at baseline. As such, it remains unknown how these variables might change over the operative course, and whether such changes are associated with dynamic alterations in opioid use, pain and other variables.
Dr. Torrie and her colleagues are still looking for other ways to distinguish patients who may be at risk for consuming more opioids after surgery.
“We are sequencing genotypic data on these patients,” Dr. Torrie explained. “Maybe we can use that data to see if certain SNPs [single nucleotide polymorphisms] are associated with psychological characteristics such as catastrophizing, and the risk of long-term opioid use.”
Genetics notwithstanding, the current findings highlight the importance of pain-related catastrophizing, which the researchers said may represent a modifiable risk factor associated with greater postoperative opioid requirements.
“If you can screen and intervene before the patients even come for surgery, then we’re that much ahead of the game,” she said.
For Chad Brummett, MD, the study continues a tradition of excellent research from the investigators.
“I think this is another study showing that we have potentially modifiable behavioral factors that are associated with increased opioid use after surgery,” said Dr. Brummett, an associate professor of anesthesiology and a senior associate chair for research at the University of Michigan Medical School, in Ann Arbor.
“It opens up the rationale for thinking about precision medicine in the perioperative period as more than pills and injections, but really starting to manage behavior and implementing prehabilitative ways to manage anxiety, depression and catastrophizing before surgery,” he added.
Such initiatives may sometimes be challenging to implement, but Dr. Brummett said it is well worth the effort. “Our group has started to work toward this pathway, and others have done the same,” he told Anesthesiology News. “With increasing access to smartphones, it’s easier than ever to train patients to better manage things like anxiety and catastrophizing before surgery.
“I say that knowing that the effects might be modest, but even modest effects could have a big impact,” he added.