Weighing the Value of Opioids and TKA Outcomes

A new modeling study suggests that the opioid medications tramadol and oxycodone delayed total knee arthroplasty (TKA) by seven to nine years and reduced TKA utilization by 4 and 10 percent respectively, however, their use decreased quality of life and increased costs as compared to cases of patients who opted for opioid-sparing strategies.

Published in the April 25 issue of Arthritis Care and Research, the study was intended to evaluate the cost-effectiveness of incorporating tramadol or oxycodone into knee osteoarthritis (OA) treatment. It uses the Osteoarthritis Policy model (OAPol) to evaluate long-term clinical and economic outcomes of knee osteoarthritis patients (mean age 60) with persistent pain.

Led by Elena Losina, Ph.D., of Brigham's and Women's Hospital in Boston, researchers evaluated three strategies:  1) opioid-sparing (OS); 2) tramadol (T); and 3) tramadol followed by oxycodone (T+O). Annual costs for tramadol and oxycodone were estimated to be $600 and $2,300, respectively.  [[{"type":"media","view_mode":"media_crop","fid":"48913","attributes":{"alt":"©Zonda/Shutterstock.com","class":"media-image media-image-right","id":"media_crop_8358108173502","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"5876","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"font-size: 13.008px; line-height: 1.538em; float: right;","title":"©Zonda/Shutterstock.com","typeof":"foaf:Image"}}]]

Based on earlier research, the study authors assumed that opioids would decrease the effectiveness of total knee arthroplasty by 10 percent. Under this assumption, tramadol cost a total of $131,000 more than opioid-sparing (acetaminophen until total knee arthroplasty or death) and decreased quality-adjusted life expectancy (QALE) by 0.01 quality-adjusted life years. Tramadol plus oxycodone cost $134,900 over opioid-sparing and reduced QALE by 11.49 quality-adjusted life years.

There are caveats to these findings. In cases where total knee arthroplasty was not an option, tramadol treatment increased QALE by 0.05 quality-adjusted life-years with a relatively small cost increase of only $1,800. This brought the incremental cost-effectiveness ratio of tramadol of $39,600 per quality-adjusted life year. The researchers assumed a willingness to pay threshold of $100,000 per quality-adjusted life year. Even in situations where surgery was not an option, adding oxycodone to the treatment protocol along with tramadol did not meet this threshold.

When total knee arthroplasty is an option, the findings were heavily dependent on the effect of opioids on the outcome of the surgery. When the researchers assumed no effect, tramadol emerged as a cost-effective option (though tramadol and oxycodone combined did not) at $26,900 per quality-adjusted life year. But if tramadol reduces knee arthroplasty effectiveness by even 5 percent, the incremental cost-effectiveness ratio came to $110,600 per quality-adjusted life year, over the $100,000 threshold.

"This analysis shows for the first time that the long-term clinical benefit of opioids is highly dependent on their effects on TKA outcomes," Losina and her colleagues wrote. "This finding underscores the need for research on the influence of opioids on TKA outcomes.”

Significance and Findings as reported in ACR:

- The finding that opioids do not appear to provide long-term clinical benefit if they diminish the effectiveness of total knee replacement suggests that, in general, clinicians should avoid prescribing opioids in patients with knee OA.

- For OA patients who are averse to total knee replacement, tramadol appears to be an effective and cost-effective treatment.

- This analysis shows for the first time that the long-term clinical benefit of opioids is highly dependent on their effects on TKA outcomes. This finding underscores the need for research on the influence of opioids on TKA outcomes.

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References:

Smith SR, Katz JN, Collins JE, et al. “Cost-effectiveness of tramadol and oxycodone in the treatment of knee osteoarthritis.” Arthritis Care & Research 2016. DOI: 10.1002/acr.22916