Table 4.

Subgroup analysis of the relationship between blood cadmium levels, anthocyanidins intake, and COPD risk at different levels stratified by smoking status

Subgroup  (Smoking)	Characteristic	Anthocyanidins(mg)  Q1(0-1.015)	Anthocyanidins(mg)  Q2(1.015–11.53)	Anthocyanidins(mg)  Q3(>11.56)
Blood. Cadmium (ug/L)	Q1(0.07,0.24)	Reference	Reference	Reference
	Q2(0.24,0.44)	1.50(0.63,3.61)	0.33(0.14,0.77) *	2.23(0.84,5.91)
	Q3(>0.44)	4.67(2.19,9.99) ***	0.79(0.40,1.56)	3.64(1.64,8.11) **
Subgroup (Non-smoking)	Characteristic	Anthocyanidins(mg) Q1(0-1.015)	Anthocyanidins(mg) Q2(1.015–11.53)	Anthocyanidins(mg) Q3(>11.56)
Blood. Cadmium (ug/L)	Q1(0.07,0.24)	Reference	Reference	Reference
	Q2(0.24,0.44)	1.51(0.66, 3.44)	0.49(0.23, 1.07)	1.16(0.50, 2.68)
	Q3(>0.44)	1.06(0.39, 2.87)	0.60(0.22, 1.68)	1.05(0.55, 2.03)

This table further explores the impact of smoking as a factor on the interaction between blood cadmium (Cd) levels, anthocyanin intake, and COPD risk. Using a reference blood cadmium level of 0.07-0.24ug/L, while varying anthocyanin intake, it categorizes individuals based on their smoking status. For example, among former smoker individuals, when blood cadmium levels exceed 0.44ug/L and anthocyanin intake is greater than 11.56mg, the risk of developing COPD is approximately 4.36 times higher compared to when blood cadmium levels are within the range of 0.07-0.24ug/L, with an equivalent anthocyanin intake (>11.56mg). (*P < 0.05; **P < 0.01)