The Association Between Socioeconomic Factors and Incident Peripheral Artery Disease in the Chronic Renal Insufficiency Cohort (CRIC)

Background

The association between socioeconomic factors and development of peripheral artery disease (PAD) has not been as well characterized compared to other cardiovascular diseases. We sought to define how annual income, sex, race, and education level are associated with newly diagnosed PAD in a well-characterized, diverse set of adults with CKD.

Methods

The Chronic Renal Insufficiency Cohort Study (CRIC) is a multicenter, prospective cohort study designed to examine risk factors for progression of CKD and cardiovascular disease. Demographic and clinical data including ankle brachial index (ABI) and interventions were collected at baseline, as well as yearly during follow-up visits. Annual income was categorized as: <$25,000, $25,000-50,000, $50,000-100,000, or above $100,000. We excluded those with pre-existing PAD, defined as enrollment ABI of <0.9 or >1.4, or missing income data. Cox proportional hazards regression was used to estimate the risk for incident PAD during CRIC enrollment, defined as a drop in ABI to <0.90 or a confirmed PAD intervention, including revascularization or amputation.

Results

A total of 3,313 patients met inclusion criteria, the mean age was 58.7 years, 56% were male, and 42% were Black. Over a median follow-up of 10.1 years, 639 participants (19%) were newly diagnosed with PAD. After adjusting for cardiovascular risk factors, all lower levels of annual household income were associated with increased incidence of PAD (income <$25,000 HR 1.7, 95% CI 1.1-2.4, P = 0.008; income $25,000-50,000 HR 1.5, 95% CI 1.1-2.3, P = 0.009; income $50,000-100,000 HR 1.6, 95% CI 1.2-2.4, P = 0.004), relative to a baseline annual income of >$100,000 (overall P-value = 0.02). In the multivariable model, there was no association between education level and PAD incidence (P = 0.80). Black race (HR 1.2, 95% CI 1.0-1.5, P = 0.023) and female sex (HR 1.7, 95% CI 1.4-2.0, P < 0.001) were independently associated with PAD incidence. Multiple imputation analysis provided similar results.

Conclusions

In the CRIC, a multi-center cohort of prospectively followed CKD patients undergoing yearly CVD surveillance, lower annual household income, female sex, and Black race were significantly associated with the PAD incidence. In contrast, level of education was not independently associated with incident PAD.