The SDS is a self-assessment scale that reflects the patient’s subjective depressive symptoms and is widely used in outpatient screening for depression. The scale contains 20 questions, and the patient’s performance over the past six months will be evaluated by answering which of the 20 questions falls into one of the four categories of “constant, frequent, sometimes, none or occasionally”, and the corresponding score will be obtained. If the total score exceeds 40, depression is present; the total score is divided by 80 and multiplied by 100% to get the percentage, with 50%-69% being mild depression, 70%-89% being moderate depression, and greater than or equal to 90% being severe depression. Some of the test questions in the scale are as follows: 1. I feel emotionally depressed; 2. I don’t feel difficulty in doing things as usual; 3. I don’t sleep well at night; 4. My heart beats faster than usual; 5. My life is meaningful; 6. I feel hopeful about the future, etc.