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Using PROMs to Guide Decision-Making in Total Knee Arthroplasty

Physicians who treat patients with joint problems have historically relied on a variety of assessments to determine appropriate treatment and measure success afterward. A physical examination along with x-rays or other imaging tests are the standard tools to inform clinical decision-making. But over the past two decades, top-tier institutions like Hospital for Special Surgery (HSS) have sought to augment these using large databases of questionnaires from patients. These patient-reported outcome measures (PROMs) generate critical information about a patient’s perceived quality of life before and after procedures and add an important, semi-quantitative dimension to the existing clinical assessment.

Certain PROMs are knee-specific and can provide an estimate of overall knee health, or the severity of the knee pathology, from the patient’s perspective. These instruments can be used to identify what patients consider clinically meaningful change – a personal threshold that can help determine if an intervention is appropriate or if less invasive treatment is warranted. If, for example, a patient reports their knee is a 4 on a 10-point scale, where a 10 is a “perfect knee”, total knee arthroplasty would appear to be a good option because surgery is likely to improve that score significantly.  However, a patient with the same radiographic findings may report their knee as an 8 out of 10, and for such a patient, surgery is not likely to result in a meaningful marginal improvement.

Recent research has shown that these measures are somewhat predictive of success or failure of knee replacement and can be used to measure the therapeutic benefit of various treatments for knee arthritis. Two PROMs instruments, knee injury and osteoarthritis outcome score (KOOS) and a shorter version called KOOS JR, were developed by researchers at HSS specifically for patients with knee osteoarthritis. The seven-item KOOS JR, which has been shown to be a robust and valid alternative to the longer iteration of the questionnaire, collects information on pain, stiffness, function in the joint and other parameters. The resulting composite score is highly predictive of how well patients respond to knee replacement surgery. 

Using PROMs for knee patients takes relatively little time. The KOOS JR questionnaire can be administered in just a few minutes by the patient prior to their appointment or even in the office setting. Clinicians can then use these reports to guide patients through their decision process and help them determine when a surgical intervention may be right for them individually. Doing so will not only educate them about their particular condition but also raise the likelihood that they will not be surprised by the outcome of their treatment.

Citing added time, cost, additional staffing requirements and other concerns – regulators and insurers have welcomed the instruments as important potential indicators of quality care. The collection of PROMs data is now routinely mandated by both public and private entities. Though these assessments may add some administrative burden, understanding how they work and how they can benefit both patients and physicians is essential.

However, experts agree that using PROMs on their own to measure quality of care or to guide reimbursement for services is premature. Indeed, no study to date has shown that using PROMs preoperatively is linked to improved outcomes for patients. That question is now the focus of a large randomized controlled trial at HSS. PROMs data – at least for the time being – should be one of many datapoints, including clinician assessment, radiographic imaging, and other measures such as range of motion. 

At present, data from even the most robust PROMs contain a certain amount of noise. Tension exists between the minimal clinically important change in a patient’s condition and the substantial clinical benefit they may experience from an intervention. And significant gaps in the understanding of PROMs remain. Too little is known, for example, about how these instruments perform across different populations of patients or how a person’s native language affects responses to a questionnaire written in English. Meanwhile variables such as age, sex and body mass index can influence results in ways that are not fully understood.

There is a lot of potential for PROMs to improve patient selection, enhance patient-involvement in decision making and allow for better delineation between different treatment options. 

- Alexander S. McLawhorn, MD, MBA, and Elizabeth B. Gausden, MD, MPH, hip and knee surgeons at HSS