Speakers Explain How to Use Performance Measures for Hip, Knee OA Research and Care

Performance-based tests (PBTs) are more of a question mark than a useful tool for too many physical therapy researchers and clinicians. Patient-reported outcome measures (PROMs) have featured more prominently in the literature, leaving PBTs in the shadows.

“PBTs evaluate what an individual can do versus what they think they can do, which is reflected in patient-reported outcomes measures,” said Christine A. Pellegrini, PhD, Associate Professor of Exercise Science, University of South Carolina Arnold School of Public Health. “PBTs can detect functional abilities and deficits the patient may or may not have or be aware of.”

Dr. Pellegrini opened a workshop, Performance Matters: Using Performance Measures for Hip and Knee Osteoarthritis in Research and Clinical Care, on Sunday, Nov. 17.

PBTs are a set of about 20 performance measures that can assess range of motion, balance, strength, exercise capacity, endurance, and other functional attributes that are important in knee and hip osteoarthritis (OA) as well as other conditions

Most PBTs are simple — counting how many times an individual can stand up from a chair and sit down again in 30 seconds, for example, requires as little equipment as a chair and a time measurement device — and minimal training. Testing is usually performed once at baseline and at least once again to assess response to an intervention.

PROMs and PBTs assess many of the same functional attributes, Dr. Pellegrini noted, but results do not always agree. Pain, anxiety, and other factors can affect the perceptions assessed by PROMs. PBT results are less affected by non-physical factors.

She advised using both approaches for the most comprehensive assessment of function and changes in function over time.

PBTs are even more useful in clinical practice. PROMs can tell the therapist what the patient thinks about their functional abilities, but PBTs measure functional reality. Repeated PBTs have the added advantage of measuring functional changes in response to physical therapy, joint replacement, and other interventions.

“You lose the value of using them if you don’t repeat the tests at least twice to document change,” said Marie Westby, PT, PhD, Associate Professor of Physical Therapy, Mary Pack Arthritis Program Centre for Aging SMART, University of British Columbia, Canada. “PBTs can help in clinical decision-making and in treatment planning. And repeat testing motivates patients and keeps them enthusiastic with their physical therapy program.”

PBTs are also useful screening tools. Tests that assess balance, such as the four-square test in which the patient steps sequentially into four squares formed by a cross marked on the floor, then reverses direction to step in all four squares again, are an easy screen for fall risk.

Static tests, such as standing on one foot, can also assess fall risk, Dr. Westby noted, but patients are typically more engaged in active tests. And PBTs that involve movement can provide more useful information about physical functioning than many static tests.

A survey of physical therapists in British Columbia suggested that PBTs are more common than PROMs in clinical practice, Dr. Westby said. But use is far from universal. Physical therapist responses suggested diverse and contrasting attitudes, beliefs, and knowledge as well as concern about using PBTs across different patient subgroups.

Lack of resources is a common barrier, as well as problems finding quiet, private, unobstructed testing space. And administrative support is often lacking.

A Canada-wide survey of knee replacement patients and clinicians found divergent views. Patients ranked PBTs as among the most important quality indicators in knee replacement care, while clinicians were more focused on physical exam and other clinical test results.

“That mismatch is an educational opportunity,” Dr. Westby said.