Development and feasibility of a personalized, interactive risk calculator for knee osteoarthritis

Abstract

Background: The incidence of knee osteoarthritis (OA) is rising. While several risk factors have been associated with the development of knee OA, this information is not readily accessible to those at risk for osteoarthritis. Risk calculators have been developed for several prevalent chronic conditions but not for OA. Using published evidence on established risk factors, we developed an interactive, personalized knee OA risk calculator (OA Risk C) and conducted a pilot study to evaluate its acceptability and feasibility.

Methods: We used the Osteoarthritis Policy (OAPol) Model, a validated, state-transition simulation of the natural history and management of OA, to generate data for OA Risk C. Risk estimates for calculator users were based on a set of demographic and clinical factors (age, sex, race/ethnicity, obesity) and select risk factors (family history of knee OA, occupational exposure, and history of knee injury). OA Risk C presents personalized risk of knee OA in several ways to maximize understanding among a wide range of users. We conducted a study of 45 subjects in a primary care setting to establish the feasibility and acceptability of the OA risk calculator. Pilot study participants were asked several questions regarding ease of use, clarity of presentation, and clarity of the graphical representation of their risk. These questions used a five-level agreement scale ranging from strongly disagree to strongly agree.

Results: OA Risk C depicts information about users' risk of symptomatic knee OA in 5 year intervals. Study participants estimated their lifetime risk at 38 %, while their actual lifetime risk, as estimated by OA Risk C, was 25 %. Eighty-four percent of pilot study participants reported that OA Risk C was easy to understand, and 89 % agreed that the graphs depicting their risk were clear and comprehensible.

Conclusions: We have developed a personalized, computer-based OA risk calculator that is easy to use. OA Risk C may be utilized to estimate individuals' knee OA risk and to deliver educational and behavioral interventions focused on osteoarthritis risk reduction.

Figures

Fig. 1

Risk Calculator User Inputs – This figure shows the first page of the Osteoarthritis Risk Calculator. Users enter their demographic and risk-related information, which the calculator cross-references against OAPol model outputs in order to determine each user’s individual risk of knee osteoarthritis and total knee replacement

Fig. 2

Graphical Risk Information – This figure shows an example of the first set of personal risk information provided to subjects in the form of bar graphs. In this example, we have included risk information for a 55 year-old white, non-obese woman with a family history of OA but with no occupational exposure or history of knee injury. OA Risk C users are presented with their 5-, 10-, 15-, 20-, 25-, 30-year and lifetime risk of knee OA and total knee replacement. By clicking “What does my risk mean?” users may view the same data in icon array form

Fig. 3

Icon Array Risk Information – This figure shows the pop up that appears when calculator users click “What does my risk mean?” Participants can click on the dropdown menu (“Show my:”) to select the timeframe (5-, 10-, 15, 20-, 25-, 30-year or lifetime) for which they want to view their risk in icon array form

Fig. 4

Interactive Graphical Risk Information – This figure shows the interactive page of the risk calculator. Users can select from dropdown menus to add or remove risk factors and observe how their risk changes. Users can also click “What does my risk mean?” in order to view the same information in icon array form

Fig. 5

Comparison to the Average American – This figure shows the participant how their risk of developing knee OA or undergoing TKR compares to the Average American with no risk factors over several time frames (5-, 10-, 15-, 20-, 25-, 30-, and lifetime risk). The bar graphs show the user’s risk in yellow and the Average American’s risk in blue

Fig. 6

Pilot Study Recruitment – This figure shows the pilot study recruitment process. The number of subjects deemed eligible and ineligible to participate at each enrollment stage, along with reasons for ineligibility, are included

Fig. 7

Usability and Clarity of OA Risk Calculator – This figure shows participant responses to six questions about the usability and clarity of OA Risk C. Each of these questions offered responses on a 5 point Likert scale with the following agreement options: “Strongly Disagree,” “Disagree,” “Neutral,” “Agree,” and “Strongly Agree.” The first statement that users rated (“Easy to Use”) was: “The risk calculator was easy to use.” The second statement (“Overall Risk Clear”) was: “My risk of developing knee osteoarthritis was clear and easy to understand.” The third statement (“Graphs Clear”) was: “The graphs showing my risk were clear and easy to understand.” The fourth statement (“Average Risk Clear” was: “My risk of developing knee osteoarthritis compared to the average American was clear and easy to understand.” The fifth statement (“Text Readable”) was: “The text in the risk calculator was easy to read.”