Table 4.

The assignment of independent variables.

Independent variable	Variable name	Assignment description
Age (years)	X1	≤39 = 1, 40–59 = 2, 60–79 = 3, ≥80 = 4
Educational level	X2	Primary school or below = 1, junior high school = 2, senior high school = 3, university or above = 4
Disease type	X3	Circulatory system diseases = 1, musculoskeletal diseases = 2, respiratory diseases = 3, digestive system diseases = 4, hematological diseases = 5, urinary system diseases = 6, endocrine and metabolic diseases = 7, neurological diseases = 8, other = 9
Self-perceived severity of disease	X4	Mild = 1, moderate = 2, severe = 3
Anxiety	Y	Yes = 1, no = 0