Pregabalin Reduces Chronic Neuropathic Pain After Total Knee Replacement Surgery: Presented at ASA
"Pregabalin Reduces Chronic Neuropathic Pain After Total Knee Replacement Surgery: Presented at ASA"
By Deborah Brauser
Doctor's Guide Dispatch
ORLANDO, Fla -- October 21, 2008 -- Perioperative administration of pregabalin significantly decreases the incidence of neuropathic pain at 3 and 6 months after total knee arthroplasty (TKA), according to research presented at the American Society of Anesthesiologists (ASA) 2008 Annual Meeting.
Lead investigator Asokumar Buvanendran, MD, Department of Orthopedic Anesthesia, Rush Medical College, Chicago, Illinois, reported the results here in an oral session on October 19.
"Chronic pain syndrome is often a consequence of orthopaedic surgery," said Dr. Buvanendran. "The treatment of that is extremely difficult, costly, and debilitating for the patient. And we've seen that chronic pain with knee replacements is more severe even than with hip replacements. So that's what we looked at for this study."
Two hours prior to having primary TKA, the 240 patients enrolled in this trial were randomised; 120 received a 300-mg oral dose of pregabalin and 120 received matching placebo.
In the operating room, all patients were sedated with midazolam and a combined spinal-epidural procedure. At completion of surgery, patients received pain medication through an epidural infusion of fentanyl/bupivacaine using a patient-controlled epidural device.
For 14 days after surgery, patients received twice-daily doses of pregabalin 150 mg or placebo. Neuropathic pain was assessed by phone interviews at 3 and 6 months postsurgery using the self-administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS). Incidence of mechanical allodynia or hyperalgesia was recorded, with a chi-squared test used to compare the 2 groups.
Neuropathic pain was defined as an S-LANSS score of 12 or greater.
Results 3 months after the TKA procedure showed an incidence of neuropathic pain of 1.8% with pregabalin and 14.2% with placebo ([P = .0006). The incidence of allodynia in the operated leg was 16.4% in the pregabalin group and 29.1% in the placebo group (P = .020). Hyperalgesia in the operated leg occurred in 16.4% and 32.3%, respectively (P = .005).
Six months after surgery, incidences of neuropathic pain, allodynia, and hyperalgesia were also significantly lower in the pregabalin group versus placebo (0.9% vs 9.4%, P = .004; 6.4% vs 19.5%, P = .004; 6.4% vs 21.1%, P = .001, respectively).
Dr. Buvanendran concluded that pregabalin can lead to a decrease in chronic pain while improving patients' quality of life.
When asked to comment on the finding that 0.9% of patients in the pregabalin group reported chronic pain at the 6-month evaluation, the doctor replied, "That was impressive. Now, some might say that the placebo at that mark was also relatively low and what you normally see in clinical practice. But it's still a large population given that there are over 400,000 knee replacements done every year in this country alone."
He continued, "The overall results are a little surprising. We didn't expect it to be that much of a dramatic drop [in chronic pain]. That's why we took a large sample size, just to make sure that it is a fact."
"I think many hospitals will change clinical practice on this [finding]," he added.
Funding for this study was provided by Pfizer Inc.
[Presentation title: Perioperative Pregabalin Reduces Neuropathic Pain at 6 Months After Total Knee Arthroplasty (TKA). Abstract A-595]