Table 2.

Association between systemic immune-inflammation index and serum ferritin.

	β (95%CI), p-value
	Crude model(Model 1)	Minimally adjusted model(Model 2)	Fully adjusted model(Model 3)
SII	−0.05 (-0.07, −0.04) <0.0001	−0.02 (−0.03, −0.01) 0.0010	−0.03 (−0.04, −0.02) <0.0001
Categories
Tertile 1	Reference	Reference	Reference
Tertile 2	−21.95 (−30.83, −13.07) <0.0001	−10.80 (−18.61, −3.00) 0.0067	−13.65 (−21.37, −5.93) 0.0005
Tertile 3	−36.64 (−45.43, −27.85) <0.0001	−17.98 (−25.77, −10.18) <0.0001	−23.31 (−31.19, −15.42) <0.0001
P for trend	<0.0001	<0.0001	<0.0001

In sensitivity analysis, SII was converted from a continuous variable to a categorical variable (tertiles).

Model 1: no covariates were adjusted.

Model 2: adjusted for gender, age, and race.

Model 3: adjusted for gender, age, race, education level, PIR, BMI, alcohol consumption, smoking status, physical activity, serum albumin, globulin, alkaline phosphatase, total protein, serum uric acid, total cholesterol, serum calcium, hypertension, diabetes and depression.

OR, odds ratio; CI, confidence interval.