Study finds liposomal bupivacaine improves patient, cost outcomes after knee replacement

Use of bupivacaine liposome injectable suspension (Exparel) was associated with improved clinical outcomes and a favorable cost savings per patient compared to the standard of care, according to data presented at the 27^th annual meeting and expo of the Academy of Managed Care Pharmacy in San Diego.

Bupivacaine liposome injectable suspension is currently indicated for single-dose infiltration into the surgical site to produce postsurgical analgesia.

Carl V. Asche, PhD, and Carmen S. Kirkness, PT, PhD, of the University of Illinois College of Medicine, and colleagues compared 2 matched cohorts of 134 patients who received either a liposomal bupivacaine-based regimen or the usual pain management regimen (continuous nerve block with ropivacaine and/or local infiltration with varying combinations of ketorolac, ropivacaine, epinephrine and morphine sulfate). They then compared various effectiveness and cost measures between the 2 groups, quantified the ‘benefit’ of the liposomal bupivacaine group over the control group and performed a cost-benefit analysis.

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The study found that using liposomal bupivacaine vs. the standard of care to manage pain after total knee replacement (TKA) can reduce hospital costs per patient by improving key patient outcomes such as earlier ambulation, greater ambulation distance and shorter length of hospital stay. Savings of $366 per patient on direct hospital costs ($8,816 + $1,717 for the liposomal bupivacaine group vs. $9,182 + $2,031 for the control group; P>0.05) were realized.

“When a new, and often times, costlier drug enters a hospital, formulary managers are routinely tasked with performing drug utilization evaluations [DUE] to determine whether the benefit of the new therapy outweighs its incremental costs,” explained Ashe, director of the Center for Outcomes Research at the University of Illinois College of Medicine in Peoria. “Monetizing a drug's ‘benefits’ and then making an unbiased assessment on whether the new drug is more cost-effective than the standard of care is one of the major challenges when doing a DUE, and the precise problem we set out to solve.” 

NEXT: Two key insights on reducing subjective biases

The study provides 2 key insights on how to reduce some of the subjective biases which can often confound DUEs, according to Kirkness, assistant director, Center for Outcomes Research and assistant professor, department of medicine, University of Illinois College of Medicine.

“First, by comparing matched cohorts of patients--a ‘historical’ group as the control and a ‘prospectively’ identified treatment group, eliminates variability and levels the playing field for the comparative outcomes analysis,” she said. “Second, calculating costs and benefits using objective measures such as the direct and indirect contributors to ‘cost’ such as room and board, pharmacy and diagnostics, provides an accurate calculation of the relative ‘benefit’ of the new drug.”

In the case of liposomal bupivacaine, for example, it would be short-sighted to evaluate its benefit-cost based on outcomes such as pain scores and patient satisfaction, which are unlikely to show statistically significant improvement over the current standard, to justify the incremental short-term cost, Kirkness explained.

“However, as our study found, if you take a broader look at the impact of [liposomal bupivacaine] on cost-driving outcomes such as hospital stay, its value is irrefutable and more than offsets its incremental cost,” she said.

“Quantifying and monetizing benefits requires the assessment of multiple objective and subjective measures, and without considering all the important aspects along the continuum of care, we run the risk of writing off new therapies and interventions that could not only advance patient care, but result in meaningful costs savings in the long run,” Ashe said. “By determining the clinical benefits and costs of a new drug therapy, hospitals can make an objective decision that maximizes service to the patient by utilizing the most effective therapy; whether it is a new drug or continuation of current processes.”

Other members of the study team included: Ed C. Rainville, MSPharm, clinical pharmacy, OSF St. Francis Medical Center; Minchul Kim, PhD, Center for Outcomes Research, U of Illinois College of Medicine; Jinma Ren, PhD, Center for Outcomes Research, U of Illinois College of Medicine; and Meagan McManus, OTR/L, OSF St. Francis Medical Center.

Disclosures: Authors are responsible for the design, conduct, analysis and reporting for the study. Pacira Pharmaceuticals assisted with the printing of the poster. Carl Asche has served on an advisory board for Pacira Pharmaceuticals.