A new study finds that patients with knee osteoarthritis who rely on prescription opioids for pain relief prior to undergoing total knee replacement (TKR) surgery tend to have worse postoperative pain outcomes compared to patients who do not take opioids.
The findings are published in the Journal of Bone and Joint Surgery.
Researchers at Brigham and Women’s Hospital evaluated pain relief associated with TKR surgery and found that patients who had been taking opioids to help manage pain prior to surgery experienced less pain relief after TKR surgery and had higher pain catastrophizing — the degree of an exaggerated, negative response to pain.
“With these study results, we’d encourage physicians to consider discussing long term implications of opioid therapy with their patients,” says Elena Losina, Ph.D., lead author, director of the Policy and Innovation Evaluation in Orthopedic Treatments Center and co-director of the Orthopedics and Arthritis Center for Outcomes Research at Brigham and Women’s Hospital.
“Although each patient case is different, patients and physicians should discuss the potential impact of using opioids in patients with knee osteoarthritis who are likely to consider total knee replacement within the next two years.”
Patients with knee osteoarthritis often live with chronic pain and significant activity limitation. Although TKR is an effective treatment in relieving pain and restoring function, patients spend an average of 13 years using non-surgical options for pain management including the use of non-steroidal anti-inflammatory drugs, physical therapy, and intra-articular injections.
Use of opioid painkillers have increased significantly — nearly 40 percent of Medicare patients with knee osteoarthritis received at least one opioid prescription in 2009. The authors state that the U.S. spends over $1.5 billion per year on prescription opioids for knee osteoarthritis.
Although prior research has shown that using opioids preoperatively is associated with poor pain outcomes, these studies had limited sample sizes and pain catastrophizing was not considered.
The team analyzed the data of 156 patients who had undergone TKR at an average age of 66. They collected patient-reported outcomes and demographic data both before and six months after surgery, and abstracted data regarding opioid use from the patients’ medical records. They found that prior to surgery, 23 percent of patients had at least one opioid prescription.
Using standard pain scales — the Pain Catastrophizing Scale and the Western Ontario and the McMaster Universities Osteoarthritis Index (WOMAC) — the researchers measured the pain levels of patients undergoing TKR.
They used sophisticated analytic methods to compare the change in the WOMAC pain score six months after knee surgery and establish the difference between patients who had and those who had not used opioids before TKR.
The findings show that patients who used opioids before going into surgery had about nine percent less pain reduction at six months following surgery.
“Our findings support previous research that indicated preoperative opioid use was associated with worse clinical outcomes. This data demonstrates that preoperative opioid use may also lead to lesser pain relief in the early postoperative period,” said Losina.
Furthermore, since the U.S. spends over $1.5 billion annually on prescription opioids for patients with knee osteoarthritis, and nearly $30 billion on illicit use, reducing the use of opioids may decrease their harmful effects, say the researchers. Clinicians and policy makers should consider limiting the use of opioids prior to TKR to optimize post-TKR pain relief.
Source: Brigham and Women’s Hospital