Six months after knee replacement surgery, pain outcomes were not as good for patients who previously took prescription opioids, according to a study published in The Journal of Bone & Joint Surgery.
“Our results should be viewed as a warning that using opioids during the preoperative period may be problematic due to their negative effects on subsequent TKA [total knee arthroplasty] outcomes,” said Elena Losina, PhD, Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Boston, Massachusetts.
For the study, the researchers analysed data on 156 patients who underwent TKA at their hospital between 2011 and 2013. The average age was about 66 years and 62% of patients were women. Average pain score before surgery was about 44 on a 100-point scale, with 100 being the worst score.
During the 2 years before TKA, 23% of patients had received at least 1 prescription for opioid pain relievers, and 9% had multiple opioid prescriptions. Nearly all patients received opioids for pain relief after surgery.
Six months after TKA, pain scores and other outcomes were compared for patients with and without previous opioid prescriptions. The analysis included a propensity score to account for other factors associated with an increased likelihood of using opioids.
After surgery, the previous opioid users had a higher average pain score: about 17, compared with 10.5 for those who did not receive opioids. The difference in postoperative pain-score reduction between the two groups was significant after adjusting for preoperative pain score and other health conditions.
The factor most strongly related to preoperative opioid use was an elevated score for pain catastrophizing.
“Pain catastrophizing may play an important role in decisions by physicians and patients to use opioids, which then places [patients] at risk for poorer outcomes,” said Dr. Losina.
The findings support and expand on previous evidence that preoperative opioid use leads to worse clinical outcomes after total joint replacement and other major orthopaedic surgery procedures. Considering the long duration of knee pain most patients experience before they finally undergo TKA, the study may have important implications for creating appropriate treatment guidelines.
“Clinicians and policy makers may consider limiting the use of opioids prior to TKA to optimise post-TKA pain relief,” the authors concluded.