Abstract PO-208: The value of estimating spillover effects in health equity interventions: A case study to promote mammogram uptake among African American women and their social networks
Authors: Bergeron Nyahne , Fitzpatrick Veronica , Asche Carl , Watson Karriem S. , Khanna Aditya S. , Hempstead Bridgette , Calhoun Elizabeth A. , McDougall Jean , Molina Yamilé 
Published: January 2022

Abstract
Introduction: Standard economic evaluation methods may underestimate the value of health equity interventions by focusing exclusively on program costs and direct effects on participants' health. Yet, these interventions have spillover effects – wherein participants transition from being intervention recipients to becoming health advocates for their social networks. Consequently, interventions may improve the health of participants and other community members who are not directly connected with interventions. This study demonstrates the utility of incorporating spillover effects by comparing incremental cost-effectiveness ratios via a patient navigation intervention to promote mammography screening among African American (AA) women. Specifically, we compare the relative costs and cost-effectiveness when including mammography uptake of: (1) AA intervention participants (egos) only versus (2) AA intervention participants (egos) and their screening eligible social network members (alters). Methods: Our study draws from two studies: (1) an individual randomized trial to test the efficacy of patient navigation on mammography uptake (Patient Navigation in Medically Underserved Areas [PNMUA]) and (2) an observational ancillary study to test the effects of PNMUA on breast cancer survivor egos and their alters (Offering AA Survivors Increased Support [OASIS]). Overall, we used a healthcare system perspective. For 2021 cost data, we collected data from study records and expense reports. For effects data, we used: (1) medical record data for egos' mammography uptake, (2) self-report data from egos regarding their alters' mammography uptake, and (3) self-report data from alters about their own mammography uptake. We consequently computed incremental cost-effectiveness ratios (ICERs), using different data sources, to assess the impact of estimating spillover effects on economic evaluation of patient navigation. Results: Total cost of the intervention was $196,601. The greatest expense were breast cancer navigators' salaries and fringe rates ($126,745). In PNMUA, more navigated vs. non-navigated egos obtained biennial mammograms (45% vs. 39%). In terms of spillover effects, more navigation arm alters obtained biennial mammograms compared to alters in the non-navigated arm (ego self-report: n=1296 vs 949; alter self-report: n=1521 vs. 1195). Navigation had lower value when only incorporating participants' mammography uptake ($3,277 per each additional woman screened) versus when incorporating spillover effects ($2,027-$2,114 per each additional woman screened). Conclusion: Our results suggest breast cancer navigation programs may be more valuable when including spillover effects. This case study provides insight with real-world applicability into integrating spillover effects into economic evaluation. Our methods offer a new avenue for improved cost and effect estimates of health equity interventions, which may be useful for assessing future resource allocation in healthcare practice and policy.
Citation Format: Nyahne Bergeron, Veronica Fitzpatrick, Carl Asche, Karriem S. Watson, Aditya S. Khanna, Bridgette Hempstead, Elizabeth A. Calhoun, Jean McDougall, Yamilé Molina. The value of estimating spillover effects in health equity interventions: A case study to promote mammogram uptake among African American women and their social networks [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-208.