Consideration of Opioid Use in Total Knee Arthroplasty

As the opioid epidemic continues throughout the United States, the use of this drug for pain management is under careful consideration. During a session at the AAOS 2018 Annual Meeting, speakers discussed pain management for patients undergoing total knee arthroplasty (TKA), and a number of presentations focused on opioid use in this patient population. This is a highlight of some of the study findings.

In the first study, researchers from the University of Chicago Medicine & Biological Sciences assessed the association between preoperative opioid use and postoperative complications and healthcare utilization.

Using the Truven Health Analytics MarketScan® database from 2003 to 2014, researchers identified patients with a Current Procedural Terminology code for primary TKA or total hip arthroplasty (THA) who were enrolled for at least six months prior to the index procedure. They identified two study populations that encompassed approximately 700,000 patients: those with 12 months and three years of continuous postoperation follow-up.

The researchers evaluated stratified duration of preoperative opioid use and compared the rates of arthroplasty revision and 30-day hospital readmission. After controlling for age, gender, and Charlson Comorbidity Index, there was a statistically significant increased risk of revisions and 30-day readmission after TKA and THA with increased preoperative opioid use. There was also an increased risk of poor outcomes and increased postoperative healthcare utilization in patients with long-term opioid use.

“Preoperative opioid use should be considered when doing risk stratification,” the researchers concluded.

Next, researchers from New York University (NYU) assessed patient factors related to opioid abuse following surgery. “The narcotic epidemic affects this industry,” they said, noting that patients are in pain. Higher narcotic use correlates with poor postoperative outcomes, including longer length of stay, increased adverse events, and reduced pain control.

The researchers included 338 consecutive TKA candidates between February and June 2016 and conducted an extensive chart review, including baseline demographics, medical comorbidities, surgeries, and social history. They assessed the morphine milligram-equivalence (MME) three months prior to surgery and six months postoperation. Chronic opioid use was defined as ≥20 MME for more than 30 consecutive days.

They found that the average daily MME is substantially elevated in persistent chronic users compared with those who are cured:

• Preoperatively: 22.0 vs 21.8 MME/day (p=0.01)
• Postoperatively: 24.6 vs 99.0 MME/day (p<0.001)

“Our results indicated [that] 57.4% (n=31) of chronic users stopped chronically using opioids, while 42.6% (n=23) continued chronic use at six months postoperation,” the investigators concluded. A history of multiple surgeries and smoking increased the risk for persistent opioid use. The researchers recommended that a history of preoperative narcotic use be screened and optimized in TKA candidates prior to surgery. Future multicenter studies should assess narcotic patterns with the aim of developing risk stratification tools used to identify high-risk TKA candidates, the researchers noted.

Lastly, another group of researchers from NYU assessed factors that impact postoperative pain control and function following total joint arthroplasty. The researchers assessed whether standardized preoperative questionnaires can help identify patients who may:

• Experience greater postoperative pain
• Require more narcotics for pain control
• Encounter difficulties with physical therapy
• Require greater lengths of stay
• Require subacute rehabilitation for discharge
• Have increased cost burden

A total of 111 patients undergoing unilateral, primary, total hip and knee surgeries were prospectively enrolled and completed a series of 11 preoperative questionnaires. The scores were analyzed with several inpatient metrics in mind, including patient-reported pain scores, narcotic use, physical therapy milestones, hospital length of stay, discharge disposition, and direct inpatient costs.

They found lower preoperative pain domain scores were correlated with higher predictive postoperative pain scores on postoperative day one (p=0.001) and two (p=0.006). No other areas of research correlated with postoperative pain scores.

Lower preoperative patient-reported pain domain scores were correlated with higher daily narcotic use on postoperative day two (p=0.029) and three (p=0.028), as well as overall higher total inpatient narcotic use (p=0.031).

No single preoperative questionnaire demonstrated a strong relationship with postoperative pain control and functional recovery. However, patients with lower baseline patient-reported outcome measures (specifically in the pain domain), depression, or pain catastrophizing have higher pain scores and increased narcotics usage. Patients identified as pain catastrophizers or those with lower social support may be more likely to be discharged to acute care facilities.

“Pain surveys are here to stay and we need to conduct research to see how to best use these and help coordinate care,” the investigators concluded, noting that more research is needed to determine the utility of patient-centered questionnaires and to define the relationship with short-term outcomes.