Mount Sinai study finds knee replacement benefits accrue mostly in severe population

March 30, 2017 – 8:43 AM | By Andrea Gonzalez | No comments yet

By Stacy Lawrence, Staff Writer

New research published in the BMJ finds that total knee replacement may be most useful in osteoarthritis patients with the most severe symptoms, with little quality of life or economic benefit from the use of the procedure in the less severe patient population.

The researchers suggested that a more rigorous assessment for individual patients of the potential risks and benefits of knee replacement, as well as better optimization of more conservative interventions, could help to improve population-level outcomes and the economic utility of the procedure. The study authors call for further research to advance these benefit/risk prediction tools as well as the relative efficacy of other kinds of interventions.

SEVERITY MATTERS

“You could say we used a more unique approach to look at before and after to compare outcomes for patients who did not have the knee replacement or had knee replacement later and we looked at similar patients to compare outcomes,” Bart Ferket, assistant professor at the Department of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai and lead study author, told Medical Device Daily.

“We did the same, at the same time points, for patients who did not have knee replacements. We found that the improvements are, on average, generally lower than found in other studies and we conducted a cost-effectiveness analysis using those improvements,” he added.

An estimated 12 percent of U.S. adults have osteoarthritis of the knee. There are more than 640,000 knee replacements a year in this population for a total estimated cost of about $10.2 billion. The annual rate of the procedure has doubled since 2000, mostly due to the expansion into patients with less severe physical symptoms, but the Mount Sinai researchers questioned the usefulness of that treatment strategy.

There has only been one randomized, controlled trial to evaluate total knee replacement as an adjunct to optimized nonsurgical treatment; and that prior study did not take into account relative symptom severity.

“What would happen if we allocate only knee replacement only to patients with severe symptoms? Cost decreases if we only performed it in severe patients; costs would go down but that would not lead to the loss of total population efficacy,” concluded Ferket.

STUDY SETUP

The researchers analyzed data from two U.S. cohort studies. One with 4,498 participants with or at high risk for knee osteoarthritis from the Osteoarthritis Initiative (OAI), and the other 2,907 patients from the Multicenter Osteoarthritis Study (MOST). Patients were followed up for nine years in the former study and two years in the latter one.

Overall quality of life was assessed using a standard measure of physical and mental function, known as SF-12, as well as with other osteoarthritis-specific quality of life scores. Based on that data, the study then estimated quality adjusted life years (QALYS) and assessed them in context of lifetime costs.

The research found that improvements increased with decreasing patient functional status at the initial baseline data. But, taken as a whole amongst all levels of severity, total knee replacement had minimal effects on quality of life and QALYs at the group level.

“Our findings show opportunity for optimizing delivery of total knee replacement in a cost-effective way, finding the patients who will benefit the most, delivering the treatment at the correct point in their disease progression, and optimizing the cost so we can deliver the benefit to all who need it,” said Madhu Mazumdar, director of the Institute for Healthcare Delivery Science at the Mount Sinai Health System and Professor of Biostatistics in the Department of Population Health Science and Policy at the Icahn School of Medicine at Mount Sinai and study co-author.

The researchers argue that little effort is made to exhaust non-surgical medication and other options prior to proceeding to knee replacement, and that better use of these could help to manage symptoms in less severe patients.

These non-surgical options include osteoarthritis pain medication included acetaminophen (paracetamol), non-steroidal anti-inflammatory drugs (NSAIDs) and cyclo-oxygenase-2 (COX-2) inhibitors. Beyond drugs, other options include massage, chiropractic and acupuncture treatments.

It’s worth noting that funding for the cohort studies used in the analysis was provided by the National Institutes of Health, Merck Research Laboratories, Novartis Pharmaceuticals Corporation, Glaxosmithkline plc and Pfizer Inc.

IMPROVING PRACTICE

“For current practice, our study has a take-home message that not all patients with osteoarthritis are expected to benefit from total knee replacement. That likely depends on the severity of physical symptoms that these patients experience,” said Fekert. “We believe that more research should be done looking at more conservative treatments with proper education to patients, recommended exercise and weight loss in patients who are overweight.”

Weight loss and exercise to strengthen the knee and improve aerobic fitness, as well as using the best medication, could be sufficient for less severe patients, eliminating or extending their need for an eventual knee replacement.

“Acetaminophen or topical NSAIDs, alternative treatments such as hot and cold compresses and transcutaneous nerve stimulations – patients should be using these in an optimal way before being treated. But in many cases, conservative treatment options have not been optimized before surgery. We need to identify how to better deliver conservative treatment programs,” Fekert added.

He would also like to see physicians routinely using predictions tools that can evaluate the potential benefit, as well as the harms and health care costs associated with pursuing a particular path. There are several studies that have proposed such prediction models, but Fekert noted that they need to be validated to ensure their usefulness more broadly outside of their particular study sample.

Fekert cautioned that this analysis doesn’t give answers to individual patients. He noted that individuals must decide for themselves if they will be happy with what will perhaps be a small improvement, despite the risks and costs. But the data do speak to broader usage trends – and their appropriateness.

“There’s a variation in utilization of the procedure, so it’s very difficult to put your finger on it,” he said. “Even considering the prevalence of disease across countries, you still end up with questions and use is not in concordance with distribution. In the U.S., utilization is probably the highest among all Western countries.”

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