Table 5. Risk differences of amputation, revascularization, or hospitalization for medical treatment comparing diabetic patients receiving peripheral artery stenting (N = 659) vs. bypass surgery (N = 5,652) by instrumental variable analyses^*.

	Crude analysis		Analysis using calendar year as IV		Analysis using patients’ monthly income level as IV		Analysis using regional difference as IV
	Risk difference (95% CI)	P value	Risk difference (95% CI)	P value	Risk difference (95% CI)	P value	Risk difference (95% CI)	P value
Amputation	−0.083 (−0.105, −0.061)	<0.0001	−0.003 (−0.053, 0.046)	0.89	0.058 (−0.055, 0.171)	0.31	0.148 (0.068, 0.227)	<0.001
Foot, ankle, leg	−0.015 (−0.023, −0.006)	0.02	−0.009 (−0.030, 0.013)	0.42	−0.009 (−0.058, 0.040)	0.72	0.008 (−0.026, 0.043)	0.64
Thigh	−0.058 (−0.078, −0.038)	<0.0001	0.011 (−0.033, 0.055)	0.63	0.077 (−0.024, 0.177)	0.14	0.121 (0.050, 0.192)	0.001
Amputation, revascularization, or hospitalization for medical treatment	−0.104 (−0.127, −0.080)	<0.0001	−0.027 (−0.080, 0.026)	0.31	0.016 (−0.105, 0.137)	0.79	0.142 (0.057, 0.228)	0.001

*Risk differences at 2-year using bypass surgery as the reference.

IV: instrumental variable.