A Matter of Perception

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Disagreement found between self-reported and performance-based measures of physical function.
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Osteoarthritis is a form of arthritis caused by biomechanical and biochemical processes that can lead to joint inflammation and cartilage degradation where bones meet. As the cartilage thins, the bones can rub together causing pain, stiffness and swelling. The knee is one of the most common joints affected by osteoarthritis.

Total knee replacement surgery is a last-resort treatment for people whose osteoarthritis can no longer be managed through other approaches.

Although reduced physical function is a key decider for whether surgery is the right treatment, there is currently no clinically standardized way to measure physical function in individuals with knee osteoarthritis. A team of Krembil researchers compared and contrasted two ways that are often used to assess function: a physical test and a self-reported questionnaire.

The study, published in PloS ONE, revealed that self-reported physical function scores in younger individuals tended to be worse compared to performance-based scores. In older adults, self-reported and performance-based scores were more consistent.

“An osteoarthritis diagnosis can be perceived as untimely and upsetting for middle-aged adults (45-65 years of age), particularly as they tend to be more engaged in activities such as working and activities with young children. These perceptions and experiences of disruption to normal activities may be expressed by worse self-reported function relative to measured physical function,” explains Krembil Scientist Dr. Anthony Perruccio who led the study with then graduate student Jessica Wilfong.

Disagreement between self-reported and performance-based scores was also found in individuals with more intense knee pain. Additionally, discordance, depending on sex and obesity, was associated with:

  • more symptomatic joints
  • fewer additional complicating conditions or diseases
  • higher levels of pain catastrophizing (ie, the tendency to focus on pain, ruminate about it or feel helpless towards managing it)

The performance test used by the research team involved timing how long it took patients to stand up from a chair, walk a short distance and return to the chair to sit. Longer times indicated worse functionality. They compared the results of the performance test with how patients ranked their functionality on a questionnaire.

“Our research shows that self-reported and performance-based measures provide distinctive and complementary information that lend to a holistic understanding of a patient’s physical functionality and how it impacts their life,” says Dr. Perruccio.

This work was supported by the Toronto General & Western Hospital Foundation through the University Health Network Arthritis Program.

Wilfong JM, Badley EM, Power JD, Gandhi R, Rampersaud YR, Perruccio AV. Discordance between self-reported and performance-based function among knee osteoarthritis surgical patients: Variations by sex and obesity. PLoS ONE. 2020 Jul 30. doi: 10.1371/journal.pone.0236865.

Study lead Dr. Anthony Perruccio, Scientist at the Krembil Research Institute. Photo credit: The Globe and Mail.