Table 4 shows the discriminant capability of the scores from the prediction model. Subjects in quartiles 3 and 4 of the prediction scores had a positive predictive value of 73% and 96% of being at risk for having a poor physical function. Variables significantly associated with poor physical performance (quartile 4) were age, education, physical activity, GDF-15, IL-6, and TNF-α but not DM (Table 5). Here, GDF15 is linked to diabetes mellitus.