β2-Microglobulin, cystatin C, and creatinine and risk of symptomatic peripheral artery disease

Background-β₂-Microglobulin and cystatin C may have advantages over creatinine in assessing risk associated with kidney function. We therefore investigated whether emerging filtration markers, β₂-microglobulin and cystatin C, are prospectively associated with risk of the development of peripheral artery disease (PAD). Methods and Results-We conducted nested case-control studies among women within the Nurses' Health Study (1990-2010) and among men within the Health Professionals Follow-up Study (1994-2008) with the use of archived blood samples collected before PAD diagnosis. During follow-up, symptomatic PAD was confirmed in 144 women and 143 men. Controls were matched 3:1 based on age, race, smoking status, fasting status, and date of blood sampling. Conditional logistic regression models were used to estimate relative risks (RRs) and were adjusted for plasma creatinine and cardiovascular risk factors. In women, the RRs (95% CI) per 1-SD) increment were 1.16 (0.85 to 1.58) for β₂-microglobulin and 0.94 (0.69 to 1.28) for cystatin C. Corresponding RRs in men were 1.50 (1.08 to 2.09) for β₂-microglobulin and 1.54 (1.07 to 2.22) for cystatin C. There was no association between creatinine and PAD risk in women, whereas the association in men (RR 1.41, 95% CI 1.10 to 1.81) disappeared after adjustment for either β₂-microglobulin or cystatin C. In pooled analyses of men and women, only β₂-microglobulin was associated with PAD risk (RR 1.31, 95% CI 1.04 to 1.64). Conclusions-In pooled analyses, β₂-microglobulin was associated with an increased risk of symptomatic PAD; a similar association with cystatin C was observed only in men. The findings suggest that β₂-microglobulin may capture the atherosclerosispromoting or atherosclerosis-related elements of kidney dysfunction better than creatinine.