According to a recent article published in Arthritis Care & Research, a risk calculator has proven to be a useful tool in educating about knee osteoarthritis (OA), and may even be beneficial in motivating exercise-related behavioral changes.

Little research has been done analyzing how well patients understand their risk for OA and how it affects prevention efforts. A lack of information increases their chances of under- or overestimating their risks, which may influence their efforts in decreasing their risk for OA.

For this study, a randomized trial with 375 subjects, recruited using Amazon Mechanical Turk, were either randomly provided a personalized risk calculator based on demographic and risk factor information (treatment group) or simply provided access to general OA risk information (control group).

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Study participants were asked to estimate their 10-year and lifetime risk for knee OA at baseline and after the intervention; willingness to alter their diet, exercise, and weight-control behaviors were measured using contemplation ladders. The online risk calculator used in this study was developed from the Osteoarthritis Policy Model (OAPol), incorporating risk factors from a published prediction model.

Results of the study showed that participants in both groups had an estimated 3.6% 10-year and 25.3% lifetime risk of developing knee OA. The treatment group (at baseline) overestimated their 10-year and lifetime risk of developing knee OA to be 25.4% (95% CI, 22.0%-28.8%) and 47.6% (95% CI, 43.5%-51.7%), respectively. The control group (at baseline) overestimated their 10-year and lifetime risk of developing knee OA to be 26.9% (95% CI, 23.2%-30.6%) and 48.0% (95% CI, 43.9%-52.1%), respectively.

After the intervention, study participants from the treatment group had decreased their perceived 10-year and lifetime risks of developing knee OA to 12.5% (95% CI, 10.0%-15.0%) and 28.1% (95% CI, 25.2%-31.0%), respectively; there was no change in perceived risks seen in the control group.

In addition, the treatment group was more likely to move to an action stage on the exercise contemplation ladder, with a relative risk (RR) of 2.1 (95% CI, 0.9-4.7); however, there was no change seen for weight control or diet ladders (RR, 1.0 and 1.3, respectively).

Results from this study have shown that patients using a personalized risk calculator were guided to a more accurate perception of their knee OA risk, as well as increased their willingness to improve exercise behaviors. Future studies should include a longitudinal component to address the long-term effect on behavioral changes.

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Summary & Clinical Applicability

Giving limited information to at-risk patients for knee OA increases their chances of under- or overestimating their 10-year and lifetime risks, affecting their efforts in preventive measures.

The knee OA risk calculator was effective as an educational tool for improving the accuracy for patients to predict their 10-year and lifetime perception of knee OA risk.

Knee OA was beneficial in increasing patients’ willingness to change their exercise behaviors; however, it was not beneficial in changing weight control or diet changes.


Limitations of this study included excess exposure to knee OA information by the treatment group, the short duration of the study, and the cross-sectional nature of the study; the population studied was limited to persons between the ages of 25-45 years and users of Amazon Mechanical Turk, and many already had willingness-to-change scores in the action stage before the intervention was implemented.

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Losina E, Michl GL, Smith KC, Katz JN. Randomized controlled trial of an educational intervention using an online risk calculator for knee osteoarthritis: effect on risk perception. Arthritis Care Res. 2017;69(8):1164-1170.