Table 4.

The optimal scoring scheme obtained under the guidance of ML algorithms and the SHAP method

Items	Questions	Responses	Score
Item-1: age	How old are you?	Aged 35–49	0
		Aged 50–59	1
		Aged 60–69	1.5
		Aged ≥70	3
Item-2: smoking_amount	How many cigarettes have you smoked? (packs per year)	0	0
		0–10	1.5
		10–20	1.5
		>20	1.5
Item-3: bio_fuel	Do you have exposed to biomass smoke for more than half a year?	No	0
		Yes	0.5
Item-4: short_breathe	During the past year, how much of time did you feel short of breath?	None of the time	0
		A little of the time	0.5
		Some of the time	0.5
		Most of the time	1.5
		All the time	2
Item-5: dyspnoea	When do you have dyspnoea?	No dyspnoea	0
		During strenuous activities	0.5
		During walking quickly on the flat ground or climbing a small slope	0.5
		Slower than peers when walking on the flat ground, or needs to rest	0.5
		Severe dyspnoea leads to inability to leave home, or dyspnoea when wearing and undressing	1
Item-7: cough_up	Have you ever coughed up something, such as mucus or sputum?	Never	0
		Yes, cough occasionally when having a cold or chest infection	1
		Yes, cough for a few days every month	1
		Yes, cough for most days	1
		Yes, cough every day	1

SHAP – SHapley Additive exPlanation