Spotlight on the OA Risk Calculator (OA Risk C)

The Osteoarthritis Risk Calculator (OA Risk C) is an interactive, web-based tool that presents users with their personalized risk of OA, based on demographic and basic personal information input by the users. Risk calculators have been used as an education tool in conditions like heart disease and diabetes, but no risk calculator existed for OA before the one created by the OrACORe/PIVOT team.

Our calculator uses data from the Osteoarthritis Policy Model (OAPol) to calculate risk of developing OA and, for those already diagnosed with OA, the risk of undergoing a total knee replacement (TKR). Key risk factors include female sex, obesity, occupational exposure, and history of knee injury.

To celebrate the new home of this interactive, web-based tool, this month’s post will take a closer look at the goals of the calculator and the evidence that it is effective in achieving them.

 

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Establishing the calculator’s effect on risk perception

In a paper published this October in Arthritis Care & Research, Dr. Losina and colleagues evaluated the calculator’s potential to improve subjects’ perception of their personal risk of developing OA.

 

Why Risk Perception Matters

If people are aware at a young enough age that they may be at risk for knee osteoarthritis (OA), they can take action to decrease their risk. For example, they might start exercising to maintain a healthy body weight, which helps prevent OA. But younger adults, in general, do not think about diseases such as OA that, based on their prior knowledge, affect mainly older adults. People who think their risk is low may see no need to take action, but those who think their risk is high may feel defeated; therefore, correctly understanding risk of OA is important if we want to help people prevent this disease.

How the Study Worked

We built an interactive calculator that uses basic personal information to calculate an individual’s risk of OA. We tested whether using this tool improved how accurately people estimated their own risk of OA. We also tested whether using the calculator made them more willing to change behavior to prevent OA.

Subjects were divided into two groups (Calculator Group and Control Group). The Calculator Group subjects used the risk calculator to view their own personal risk of OA. Control Group subjects only saw general (not personalized) OA risk information.

What We Learned

We found that the calculator helped individuals reassess their risk of developing OA more accurately. Those who used the calculator also moved closer to being ready to start exercising—a powerful way to help prevent OA. Control subjects’ perceived risks remained unchanged. The risk calculator is an effective educational tool to improve perception of OA risk.

 

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Clinical Perspectives

An Interview with Dr. Jeffrey Katz

 

Emma C. Lape (ECL); Jeffrey N. Katz (JNK)

ECL: How do you envision this tool being used in clinical practice? Does that look different in a primary care setting versus in rheumatology?

JNK: OA Risk C, our calculator, fits very well within the established paradigm of risk calculators. Because when it comes to risk calculators, we’re not the first—cancer and cardiovascular risk calculators are well known. The idea is that patients enter some simple information, including height, weight, family history, certain past environmental exposures, etc., and get a personalized risk. This then becomes a point of conversation for changing behaviors, such as improving diet, or quitting smoking. Our calculator fits squarely within that framework. When patients see a higher risk than they expect, it can be motivating for weight loss, for example. People aren’t always motivated by mortality risk, because it seems so far off. But people do have this sense of arthritis as a really painful condition, and they relate to that idea and find it motivating.

So, given their use as a point of conversation, risk calculators are already being embraced in primary care settings. And if you think about their role in a changing model of care, calculators could be used at intake with a nurse practitioner, for example. There are a lot of possibilities.

ECL: What do you think changes when patients perceive their risks more accurately? Can patients who already have OA do anything to modify their disease progression?

JNK: It’s true, things are more complicated for those who are in treatment for OA already. Our calculator is interesting because it provides risk of developing OA for the general population, but also the risk of undergoing TKR for those with an OA diagnosis. It’s an open question in my mind how OA patients would react to seeing their risk of TKR. Is TKR enough of a specter to motivate behavior change? Certainly I have some patients who are afraid of the surgery, and TKR looms large in their minds. But others are not so concerned—they may simply see TKR as a solution.

So overall, I think it’s a cool program to use as a motivating tool for those with OA. But its effect depends on how much of a threat TKR really is for OA patients. There are many calculators out there for onset of a condition, as I’ve mentioned. But there are fewer, I think, that show the risk of disease progression. I’ll be interested to see what that can do. ◊