Association of weight-adjusted waist index with all-cause mortality among non-Asian individuals: a national population-based cohort study

Table 3 Threshold effect analysis of WWI, BMI, and WC on all-cause mortality by two-piecewise linear regression model

Variables	number of participants/ number of events	Person-Years (years)	Adjusted HR (95%CI), P-value
Fitting by the standard linear model (WWI)	1,065/18,592	90311.67	1.13 (1.03, 1.25)
Fitting by the two-piecewise linear model
Inflection point (cm/√kg)			10.46
WWI < 10.46 (cm/√kg)	94/4,621	23816.83	0.62 (0.41, 0.94)
WWI > 10.46 (cm/√kg)	971/13,971	66494.83	1.20 (1.08, 1.33)
Log likelihood ratio			0.007
Fitting by the standard linear model (BMI)	1,065/18,592	90311.67	0.98 (0.97, 0.99)
Fitting by the two-piecewise linear model
Inflection point (kg/m²)			28.50
BMI < 28.50 (kg/m²)	583/9,246	45673.00	0.92 (0.90, 0.94)
BMI > 28.50 (kg/m²)	472/9,326	44562.83	1.02 (1.00, 1.03)
Log likelihood ratio			< 0.001
Fitting by the standard linear model (WC)	1,065/18,592	90311.67	0.99 (0.99, 1.00)
Fitting by the two-piecewise linear model
Inflection point (cm)			101.40
WC < 101.40 (cm)	528/10,233	50935.00	0.98 (0.97, 0.98)
WC > 101.40 (cm)	537/8,359	39376.67	1.01 (1.00, 1.01)
Log likelihood ratio			< 0.001

Age, gender, race, education level, ratio of family income to poverty, alcohol drinking status, smoking status, stroke status, coronary heart disease status, renal failure status, liver diseases status, myocardial infarction status, and cancer status were adjusted
Abbreviation Q, quartile; WWI, weight-adjusted-waist index; BMI, body mass index; WC, waist circumference

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