Spatial availability of federally qualified health centers and disparities in health services utilization in medically underserved areas.

Federally qualified health centers (FQHCs) improve access to care for important health services (e.g., preventive care), particularly among marginalized and underserved communities. However, whether spatial availability of FQHCs influences care-seeking behavior for medically underserved residents is unclear. The objective of this study was to examine the relationships of present-day zip-code level availability of FQHCs, historic redlining, and health services utilization (i.e., at FQHCs and any health clinic/facility) in six large states. We further examined these associations by states, FQHC availability (i.e., 1, 2-4 and ≥5 FQHC sites per zip code) and geographic areas (i.e., urbanized vs. rural, redlined vs. non-redlined sections of urban areas). Using Poisson and multivariate regression models, we found that in medically underserved areas, having at least one FQHC site was associated with greater likelihood of patients seeking health services at FQHCs [rate ratio (RR) = 3.27, 95%CI: 2.27-4.70] than areas with no FQHCs available, varying across states (RRs = 1.12 to 6.33). Relationships were stronger in zip codes with ≥5 FQHC sites, small towns, metropolitan areas, and redlined sections of urban areas (HOLC D-grade vs. C-grade: RR = 1.24, 95%CI: 1.21-1.27). However, these relationships did not remain true for routine care visits at any health clinic or facility (β = -0.122; p = 0.008) or with worsening HOLC grades (β = -0.082; p = 0.750), potentially due to the contextual factors associated with FQHC locations. Findings suggest that efforts to expand FQHCs may be most impactful for medically underserved residents living in small towns, metropolitan areas and redlined sections of urban areas. Because FQHCs can provide high quality, culturally competent, cost-effective access to important primary care, behavioral health, and enabling services that uniquely benefit low-income and marginalized patient populations, particularly those who have been historically denied access to health care, improving availability of FQHCs may be an important mechanism for improving health care access and reducing subsequent inequities for these underserved groups.