Study Measures Cost, Patient Outcomes After Total Knee Replacement

Patients having total knee arthroplasty (TKA) treated with liposomal bupivacaine were discharged to their homes sooner and had a significantly shorter hospital stay compared with patients who did not receive the drug during surgery, according to a recently published study looking at the value and cost effectiveness of the drug.

In addition, patient-reported satisfaction scores for pain and pain management were also higher. The study was published in the January 2018 issue of The Bone and Joint Journal.

Liposomal bupivacaine is sold under the name Exparel. Exparel is delivered through a proprietary foam-based delivery system and costs $300 per dose, whereas the price of generic bupivacaine is about $3 a dose. The FDA approved Exparel in 2011 for a single-dose infiltration into the surgical site to produce postsurgical analgesia and is reviewing a supplemental new drug application (sNDA) to include administration via nerve block for prolonged regional analgesia.

The use of liposomal bupivacaine is controversial and expensive when looking at pharmacy costs alone in a silo, said Richard Iorio, MD, chief of adult reconstruction at NYU Langone Medical Center, Hospital for Joint Diseases, one of the study authors, in an interview with The American Journal of Managed Care^®.

The authors hypothesized that a decrease in complications with at least equivalent pain control would lead to improved cost-effectiveness.

Currently, there are no well-defined guidelines for the best pain management protocol in patients undergoing TKA, the authors wrote. Traditional methods of management include the use of opioids, patient-controlled analgesia (PCA), and peripheral nerve blocks.

The study cited some of the side effects of other methods of pain control. Peripheral nerve blocks have been associated with an increased risk of falls, nerve injury, and temporary loss of motor function, which can delay rehabilitation. Side effects of opioids include respiratory, hemodynamic, urinary, and gastrointestinal disturbances. As a result, there has been a shift towards reducing opioid consumption, using a multimodal analgesic approach, Iorio said.

He also explained that decisions about cost-effectiveness need to be based on the entire cost of an episode.

“If you have a fall in the hospital because of a femoral nerve block, or you give a patient a narcotic and they get dizzy or nauseous and vomit and their length of stay is extended, or they get too sick from the narcotics and they don’t get good pain relief … and can’t participate in their rehabilitation, they stay in the hospital longer and they even have to go to a rehab.”

He said while $300 for 1 drug may seem expensive, an extra day in the hospital might cost close to $600, a stay in a rehab center might cost $5000 to $10,000, and a fall with a fracture after a joint replacement might cost $50,000 to $100,000. The drug has been somewhat controversial and the subject of debate as to whether or not it is worth the cost.

During the study, between September 2013 and September 2015, NYU Langone began changing how they manage pain after TKA to increase patient satisfaction and also to reduce the amount of narcotics. In May 2014, there was a department-wide transition from protocols focused on femoral nerve blocks (FNB) to Exparel.

In February 2015, PCA was removed from the protocol while continuing Exparel.

The study enrolled 1808 patients, broken down into:

• Cohort 1: 583 patients, who received FNB intra-operatively and PCA for the first 24 hours post-operatively.
• Cohort 2: 527 patients, who received liposomal bupivacaine injections instead of FNB.
• Cohort 3: 698 patients, who consisted of all patients who underwent TKA after February 2015, when PCA was removed from the protocol while continuing liposomal bupivacaine injections.

The protocol for the management of pre-operative pain for each period of time was identical and consisted of 1 administration of oral analgesics (10 mg oxycodone, 200 mg celecoxib, 1000 mg acetaminophen, 50 mg of pregnable).

During the operation, a short-acting anesthetic was administered using either 3 ml 3% chloroprocaine or 3 ml 0.5% ropivacaine. A tourniquet was used and all patients received a periarticular injection (40 cc 0.25% marcaine, 5 cc 5 mg duramorph, and 1 cc 30 mg Toradol).

In cohort 1, an ultrasound-guided injection of 20 ml of 0.25% bupivacaine was administered. The liposomal bupivacaine periarticular injection, or Exparel, was used in cohorts 2 and 3 consisting of 20 cc of liposomal bupivacaine (13 mg/cc) in 40 cc to 100 cc 0.9% normal saline and was dispersed equally throughout the posterior capsule and the overlying periosteum and soft tissue.

All patients underwent the same standardized postoperative clinical pathway and rehabilitation. But Iorio said the group getting Exparel without PCA met their physical therapy milestones more quickly, got out of the hospital faster, and had their pain more controlled.

The study recorded the length of stay, whether the patients went home or to a rehabilitation center at discharge, the 30-day readmission rates, and the Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) scores from the Centre for Quality and Patient Safety database.

A significantly higher percentage (83.5%) of patients in cohort 3 (those who received liposomal bupivacaine and not PCA) were discharged to their homes and not to a rehab facility, compared with 72.2% in cohort 1 and 77.8% in cohort 2.

The mean length of stay was significantly shorter in cohort 3 (2.7 days) compared with the other 2 cohorts.

The 30-day all-cause rate of readmission was not statistically significantly different between the cohorts (P = .08).

Patient-reported HCAHPS scores relating to pain being “well-controlled” and “overall pain management” also favored cohort 3 (P = .214 and P = .463, respectively), in which cost was significantly lower compared with the other 2 cohorts (P = .005).

The replacement of FNB injections and the removal of PCAs led to improvements in many quality measures, HCAHPS pain scores, and cost-effectiveness.

REFERENCE

Kim K, Elbuluk A, Yu S, Iorio R. Cost-effective peri-operative pain management: assuring a happy patient after total knee arthroplasty. Bone Joint J. 2018;100-B(1 suppl A):55-61. doi: 10.1302/0301-620X.100B1.