Health Disparities
Tracking the Anatomy of a Disparity: Four Unique Typologies of Changing NHB-NHW Disparities in Preterm Birth Rates Across U.S. Counties Allison Stolte* Allison Stolte Joan A. Casey Alison Gemmill Hedwig Lee Brenda Bustos Ralph A. Catalano Tim A. Bruckner
Non-Hispanic Black – Non-Hispanic White (NHB-NHW) disparities in preterm birth (PTB; gestational age <37 weeks) are persistent in the US. Studies and programs addressing such disparities often target changes in NHB-NHW rate ratios or absolute differences. Whereas these measures offer important benchmarks for examining shifts in the relative burden of PTB, they mask absolute changes in subgroup rates. NHB-NHW disparities can decrease even as group-specific rates increase, such that decreasing disparities may not indicate improved population health. In this paper, we dissect the anatomy of a disparity—separately considering changes over time to NHB and NHW PTB—to develop a typological framework for assessing disparity trends. Figure 1 presents the classification of US counties into four typologies based on changes to their NHB-NHW absolute differences between two periods: 1995-1999 and 2015-2019. Institutional Progress counties, located around metropolitan areas (and especially in Maryland and California), experienced improvements in NHB and NHW PTB and in NHB-NHW disparities. These counties had the lowest NHB and NHW PTB rates in 2015-2019, serving as success stories for addressing disparities while improving population health. Politics of Despair counties, the largest group, experienced reductions in NHB-NHW disparities driven by faster increases in NHW PTB rates. This typology closely aligns with documented trends of increasing mortality rates unique to NHW adults primarily in the US South and rural areas. In Racism as a Fundamental Cause counties, improvements in PTB rates concentrated among NHW births. This process increased NHB-NHW disparities. These counties compose the smallest group and have relatively high 2015-2019 rates of NHB PTB. Finally, Institutional Harm counties experienced increases in NHB and NHW rates and in NHB-NHW disparities. These counties serve as ‘cautionary tales’ in which widespread harm concentrated among socially disadvantaged (here, NHB) groups. The four typologies uncover the many ways disparities change and can be used to study ‘exemplary’ counties, understand causes for these changes, and devise strategies for future improvements.
