  Knee osteoarthritis (KOA) is a disease that impairs knee function and causes
pain. A radiologist reviews knee X-ray images and grades the severity level of
the impairments according to the Kellgren and Lawrence grading scheme; a
five-point ordinal scale (0--4). In this study, we used Elastic Net (EN) and
Random Forests (RF) to build predictive models using patient assessment data
(i.e. signs and symptoms of both knees and medication use) and a convolution
neural network (CNN) trained using X-ray images only. Linear mixed effect
models (LMM) were used to model the within subject correlation between the two
knees. The root mean squared error for the CNN, EN, and RF models was 0.77,
0.97, and 0.94 respectively. The LMM shows similar overall prediction accuracy
as the EN regression but correctly accounted for the hierarchical structure of
the data resulting in more reliable inference. Useful explanatory variables
were identified that could be used for patient monitoring before X-ray imaging.
Our analyses suggest that the models trained for predicting the KOA severity
levels achieve comparable results when modeling X-ray images and patient data.
The subjectivity in the KL grade is still a primary concern.
