Socioeconomic disparities in the use of cardioprotective medications among patients with peripheral artery disease: an analysis of the American College of Cardiology's NCDR PINNACLE Registry.

OBJECTIVES

The aim of this paper was to examine disparities in the use of cardioprotective medications in the treatment of peripheral artery disease (PAD) by socioeconomic status (SES).

BACKGROUND

PAD is associated with increased cardiovascular risk and is more prevalent among those of lower SES. However, the use of guideline-recommended secondary preventive measures for the treatment of PAD across diverse income subgroups and the influence of practice site on potential treatment disparities by SES are unknown.

METHODS

Within the National Cardiovascular Disease Registry (NCDR) PINNACLE Registry, 62,690 patients with PAD were categorized into quintiles of SES, as defined by the median income of each patient's zip code. The association between SES and secondary preventive treatment with antiplatelet and statin medications was evaluated using sequential hierarchical modified Poison models, adjusting first for practice site and then for clinical variables.

RESULTS

Compared with the highest SES quintile (median income: >$60,868), PAD patients in the lowest SES quintile (median income: <$34,486) were treated less often with statins (72.5% vs. 85.8%; RR: 0.84; 95% CI: 0.83 to 0.86; p < 0.001) and antiplatelet therapy (79.0% vs. 84.6%; RR: 0.93; 95% CI: 0.91 to 0.94; p < 0.001). These differences were markedly attenuated after controlling for practice site variation: statins (adjusted RR: 0.97; 95% CI: 0.95 to 0.99; p = 0.003) and antiplatelet therapy (adjusted RR: 0.98; 95% CI: 0.97 to 1.00; p = 0.012). Additional adjustment for patients' clinical characteristics had minimal impact, with slight further attenuation with statins (adjusted RR: 1.00: 95% CI: 0.99 to 1.01; p = 0.772) and antiplatelet therapy (adjusted RR: 1.00; 95% CI: 0.99 to 1.01; p = 0.878).

CONCLUSIONS

Among PAD patients, the practice site at which patients received care largely explained the observed SES differences in treatment with guideline-recommended secondary preventive medications. Future efforts to reduce treatment disparities in these vulnerable populations should target systems improvement at practices serving high proportions of patients with low SES.