Table 3.

Cause‐Specific Cox Proportional Hazards Models for Impact of Race and SES on Amputations

Variable	Model 1	Model 2	Model 3	Model 4	Model 5a
	Unadjusted	Race, Age, and Sex	Race, Age, Sex, DM, Kidney Disease, and PAD Severity	Race, Age, Sex, DM, Kidney Disease, PAD Severity, and SES	Fully Adjusted Model
Race
White	Ref.	Ref.	Ref.	Ref.	Ref.
Black	2.08 (1.98–2.19)	2.02 (1.93–2.12)	1.56 (1.49–1.64)	1.53 (1.45–1.60)	1.37 (1.30–1.45)
Ageb	···	0.99 (0.98–0.99)	0.99 (0.99–0.99)	0.99 (0.98–0.99)	0.99–0.98–0.99)
Sex
Male	···	Ref.	Ref.	Ref.	Ref.
Female	···	0.39 (0.31–0.49)	0.46 (0.37–0.57)	0.46 (0.36–0.57)	0.46 (0.37–0.57)
DM	···	···	1.71 (1.63–1.79)	1.72 (1.64–1.80)	1.64 (1.49–1.82)
CKD or ESRD	···	···	2.02 (1.89–2.15)	2.03 (1.90–2.16)	1.59 (1.46–1.73)
PAD severity
Claudication	···	···	Ref.	Ref.	Ref.
Unspecifiedc	···	···	0.88 (0.81–0.96	0.88 (0.81–0.96)	0.88 (0.80–0.96)
CLI	···	···	7.76 (7.72–8.41)	7.74 (7.14–8.39)	6.43 (5.92–6.98)
SES: median income (household) of residential ZCTA
>$40 001	···	···	···	Ref.	Ref.
≤$40 000	···	···	···	1.12 (1.07–1.17)	1.12 (1.06–1.17)

Data are shown as hazard ratio (95% confidence interval). CKD indicates chronic kidney disease; CLI, critical limb ischemia; DM, diabetes mellitus; ESRD, end‐stage renal disease; PAD, peripheral artery disease; Ref., referent; SES, socioeconomic status; ZCTA, ZIP code tabulation area.

^aFully adjusted model also adjusted for comorbidities including hypertension, coronary artery disease, congestive heart failure, chronic obstructive pulmonary disease, atrial fibrillation, carotid disease, depression, body mass index, urban/rural population mix, smoking, creatinine level, and medication use (statins, antiplatelet agents, cilostazol, and antiglycemics [insulin/oral]).

^bOne‐year increase.

^cPer International Classification of Diseases, Ninth Revision codes.