Variability in guideline-directed medical therapy among sites and operators and patient factors associated with its usage following carotid artery stenting

Background Guideline-directed medical therapy (GDMT) improves outcomes after carotid artery stenting (CAS). We examined GDMT rates and factors associated with GDMT underuse after CAS in a real-world registry, focusing on patient characteristics and site- and operator-level variability. Methods The Vascular Quality Initiative registry (2017-2018) linked with Medicare claims data was queried for adults undergoing CAS. GDMT consists of statin, antiplatelet, and, if indicated, angiotensin-converting enzyme inhibitor or angiotensin receptor blocker prescription at discharge. Differences between the receipts of GDMT groups were quantified using the standardized differences ( d ). Mixed logistic regression analysis identified patient factors associated with the receipt of GDMT, including random effect at site, operator, and operator nested within site. The median odds ratio (MOR) and intraclass correlation coefficient (ICC) quantified the variability in GDMT receipt attributable to site and operator. Results Of 9880 patients (mean age, 70.7 ± 10.1 years; 36.1% female; 11.5% non-White) from 457 sites and 1895 operators, 43.0% did not receive GDMT. The mean GDMT rate by sites was 55.7% ± 18.4%, and it was 56.8% ± 29.8% by operators. Female sex, never-smoker status, chronic lung disease, dysrhythmia, and hypertension were significantly associated with higher odds of not receiving GDMT ( P < .05). The variability was significant across sites (MOR, 1.38; 95% confidence interval [CI], 0.32-1.45; ICC, 27.7%; 95% CI, 26.3%-29.0%) and operators (MOR, 1.41; 95% CI, 1.33-1.48; ICC, 28.2%; 95%, CI 26.6%-29.7%). Conclusions More than 40% of patients did not receive GDMT after CAS, explained by patient factors and both site and operator practices. These findings highlight the need for targeted intervention to improve GDMT rates in CAS.