(P105) The impact of Medicaid Expansion on the reporting of nationally notifiable STDs: A causal inference study

BACKGROUND. Numerous studies have examined the relationship between Medicaid expansion and healthcare utilization. However, little work has investigated the relationship between this policy change and outcomes for sexually transmitted diseases (STDs). We quantified the effect of Medicaid expansion on per capita STD case reporting.

METHODS. We quantified the association between Medicaid expansion and per capita STD case reporting, accounting for reporting trends before and after expansion in 2014. We conducted this analysis separately for eight combinations of age (15-24 and 25-39) and disease (chlamydia, gonorrhea, early non-primary & non-secondary syphilis, and primary & secondary syphilis). Twenty-seven states implemented expansion in 2014 – the expansion group – and 12 have not as of 2022 – the non-expansion group. Per capita STD case reports between 2010 and 2020 were extracted from CDC’s AtlasPlus. Covariates were included to control for potential confounding and improve comparability between exposure groups. This included population growth (overall and among men who have sex with men-MSM), migration, education, and race. Covariate data were selected through review of determinants of healthcare utilization and extracted from published literature. Outcomes were fitted to fixed-effects panel regressions adjusted for covariates.

RESULTS. Medicaid expansion states had similar STD rate trends to non-expansion prior to 2014. For both gonorrhea and primary & secondary syphilis, we found that expansion was associated with a reduction in reporting in the younger age-group: 49.2 (95%CI 12.5, 85.8) and 2.7 (95%CI 0.8, 4.6) fewer reports per 100,000 population, respectively. For early non-primary non-secondary syphilis, expansion was associated with 4.2 (95%CI 2.0, 6.3) and 4.5 (95%CI 1.2, 7.7) fewer reports per 100,000 in the younger and older groups, respectively. For all other STD and age-group combinations, we found no significant effects.

CONCLUSION. Medicaid expansion was associated with decreased case reporting in some age-disease groups, particularly among younger people. Lack of uniformity in our results may have resulted from differential care seeking and utilization behavior between STDs and age groups due to differences in symptomology and clinical recommendations. This study expands our understanding of how insurance coverage affects health outcomes, but further investigation is needed to reveal the causal pathways.