Fig. 3

A simple-to-use nomogram for diagnosing PAD. Instructions for using the nomogram: Draw a perpendicular line from the axis of each risk factor to determine the corresponding “POINTS” . The total points of all risk factors are then obtained. After that, draw a line descending from the axis “TOTAL POINTS” until it reaches the axis of “Rik of PAD”. For binary variables (except “Duration”), 0 = no and 1 = yes. For duration categories, 0 = duration of diabetes≥10 years and 1 = duration of diabetes<10 years. For season categories, 0 = spring, 1 = summer, 2 = autumn, 3 = winter. For smoke categories, 0 = never, 1 = former and 2 = current. For VDD categories, 0 = serum 25(OH)D ≥ 20 ng/ml, 1 = serum 25(OH)D 10 to<20 ng/ml and 2 = serum 25(OH)D<10 ng/ml