INTRODUCTION AND OBJECTIVES Over 70% of U.S. Medicare beneficiaries are not enrolled in a fully integrated HMO (i.e. Medicare Advantage) healthcare system, yet efforts to optimize AAA screening for this population remain largely unstudied. We sought to describe for this cohort the current state and opportunities for improved screening. METHODS At-risk patients at a non-fully integrated medical center without a record of AAA imaging were identified. Data included demographics, previous out-of-network imaging and in- or out-of-network status. Qualified individuals after chart review were offered AAA screening by mail and follow-up call. Primary outcome was acceptance of screening. If declined, reasons for refusal were documented. RESULTS Of 1073 eligible patients (age 73±2 years) review of medical records and calls confirmed previous imaging in 46%. Of the remaining 578, in-network patients (n=117 [20%]) were more likely to have a PCP (95% vs. 53%, p<.001). Successful contact was more likely for patients with a PCP (OR 2.36, 95% CI 1.62 - 3.45; p<.001). Of those offered screening, 31.9% accepted. Those with a PCP were more likely to accept screening (36% vs. 6%, p=.01). Conversely, the most common declined reason was deference to the PCP (58%; TABLE). On multivariate analysis having a PCP remained the strongest predictor of screening (OR 8.81, 95% CI 1.09 - 71.06, p=.04). Of those completing screening, either ectatic (13%) or aneurysmal disease (4%) requiring surveillance was identified. CONCLUSIONS PCPs are key to optimizing AAA screening rates, and out-of-network patients are particularly vulnerable due to a lack of a PCP. To improve screening rates, at-risk patients need a PCP, and PCPs need active partnership with vascular surgeons to increase patient buy-in. Over 70% of U.S. Medicare beneficiaries are not enrolled in a fully integrated HMO (i.e. Medicare Advantage) healthcare system, yet efforts to optimize AAA screening for this population remain largely unstudied. We sought to describe for this cohort the current state and opportunities for improved screening. At-risk patients at a non-fully integrated medical center without a record of AAA imaging were identified. Data included demographics, previous out-of-network imaging and in- or out-of-network status. Qualified individuals after chart review were offered AAA screening by mail and follow-up call. Primary outcome was acceptance of screening. If declined, reasons for refusal were documented. Of 1073 eligible patients (age 73±2 years) review of medical records and calls confirmed previous imaging in 46%. Of the remaining 578, in-network patients (n=117 [20%]) were more likely to have a PCP (95% vs. 53%, p<.001). Successful contact was more likely for patients with a PCP (OR 2.36, 95% CI 1.62 - 3.45; p<.001). Of those offered screening, 31.9% accepted. Those with a PCP were more likely to accept screening (36% vs. 6%, p=.01). Conversely, the most common declined reason was deference to the PCP (58%; TABLE). On multivariate analysis having a PCP remained the strongest predictor of screening (OR 8.81, 95% CI 1.09 - 71.06, p=.04). Of those completing screening, either ectatic (13%) or aneurysmal disease (4%) requiring surveillance was identified. PCPs are key to optimizing AAA screening rates, and out-of-network patients are particularly vulnerable due to a lack of a PCP. To improve screening rates, at-risk patients need a PCP, and PCPs need active partnership with vascular surgeons to increase patient buy-in.