Pre-TKA Opioid Script Predicts Post-Op Prescription

SAN DIEGO -- Patients prescribed opioids within 3 months before undergoing total knee arthroplasty are more likely than other patients to be prescribed refills of the risky painkillers after surgery, according to a large database study presented by University of Iowa Hospital researchers.

Analyzing data from more than 73,000 patients over 7 years, orthopedic surgeon John Callaghan, MD, and colleagues found that pre-surgery "opioid use" (OU) was the most likely factor to predict post-surgery prescriptions at monthly intervals. While OU patients were 1.6 times more likely than patients not prescribed pre-op opioids (NOU) to get refills 1 month after surgery, that ratio surged to 4.9 after 3 months and 9.6 after 6 months, before leveling off for the remainder of the post-op year.

Presenting at the American Academy of Orthopaedic Surgeons annual meeting, Callaghan labeled the results "baseline data;" he hopes researchers and other orthopedic surgeons utilize them to further study opioids and joint replacement, and address the Academy's recently-issued guidelines.

"The guidelines are in place" via an information statement, Callaghan noted, but "we don't know how many (orthopedists) are following them."

In addition to pre-op prescriptions, the researchers also found patients who were female, younger than 50, and manifesting one of several comorbidities to be more likely to get a post-surgery prescription. Among OU patients only, every patient factor researchers examined predicted a significantly higher risk ratio for post-op prescriptions -- at every monthly interval.

Scouring the Humana Inc. database via Pearldiver, the researchers identified 73,959 patients who underwent TKA from 2007-2014 and remained in the dataset from 3 months prior to 1 year after surgery. Nearly one-third were prescribed opioids within 3 months before surgery, with the annual percentage increasing by an average of 0.9% annually.

Findings were consistent with others reported in recent literature citing high pre-op opioid use in the U.S., Callaghan said; he cited as a comparison a French insurance database study showing only 9.3% of knee arthroplasty patients were prescribed pre-op opioids and 6.6% got the medications within one year post-op (as opposed to 69.3% in Callaghan's study).

This trend may "reflect(s) the substantially higher, and potentially unnecessary, level of opioid prescribing within the (U.S.) that is contributing to the current opioid epidemic," according to presentation notes Callaghan shared with MedPage Today.

The acronym "OU" is a bit misleading because researchers could not determine if patients actually used the medications they were prescribed. Other study limitations included not knowing patient dose or the diagnosis connected to prescription, and using an insurance administrative database. "This is a first cut," Callaghan said. "That's how I see large database studies."

Callaghan's team is now examining prescribing rates specific to orthopedic surgeons he said, in light of a 2015 webinar published in the Journal of the American Academy of Orthopaedic Surgeons showing the profession's high contribution to the opioid epidemic.

Anecdotally, he is encouraged by pain management programs working to help reduce post-op prescriptions, he said, especially for patients addicted to opioids.