Severe Maternal Morbidity and Health Equity: Impactful Racial Disparities Research Relying on Population-Based Surveillance Data Open Access

Labgold, Katie (Spring 2022)

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In the United States (US), there are racial disparities in adverse maternal health outcomes, known as severe maternal morbidity (SMM). Gaps in our understanding of the epidemiology of SMM may be contributing to persisting disparities. This dissertation seeks to advance maternal health equity by conducting rigorous epidemiologic research on SMM racial disparities using population-based surveillance data. We used Georgia 2006-2019 hospital discharge records linked with birth and fetal death certificates among Non-Hispanic (NH) Black and NH White women, ages 15-49 years.

In aim 1, we investigated how the choice of SMM case definition alters conclusions about the magnitude of the Black-White racial disparity in SMM incidence. Results suggested that the magnitude of the relative Black-White disparity was greatest when the case definition required a longer length of hospital stay (LOS) (rate ratio: 2.0). Conclusions on the absolute scale varied across all case definition modifications (rate difference: 31.2-96.4 events per 10,000 hospitalizations). After reviewing the peer-reviewed literature and considering conceptual challenges in SMM measurement, we recommend an SMM case definition including postpartum hospitalizations, excluding the blood transfusion indicator, and including any LOS. 

In aim 2, we estimated the proportion of the Black-White disparity in SMM risk operating through hypertensive disorders of pregnancy (HDP). We estimated that NH Black women experienced an excess risk of 55.7 SMM events per 10,000 hospitalizations compared to NH White women. After blocking the pathways through HDP, the excess risk among NH Black women decreased to 41.1 SMM events (proportion eliminated: 26%).

In aim 3, we estimated the joint effect of neighborhood relative income inequality and racial segregation on SMM incidence. Results indicated that neighborhood racialized income inequality produced greater than expected SMM risk based on income inequality and racial segregation alone (interaction contrast: 26.4). 

Our findings contribute to racial disparities research by identifying a conceptually strong SMM case definition. Further, these findings add to our understanding of the epidemiology of SMM incidence and Black-White disparities at both the individual and neighborhood level in the unique context of the southern US. Sustained research on structural and proximal modifiable determinants of SMM incidence and Black-White disparities is needed.

Table of Contents

Table of Contents

Chapter 1: Introduction to investigating Black-White racial disparities in severe maternal morbidity risk... 1

Overview of severe maternal morbidity... 1

Health equity assumptions for investigating racial disparities in SMM risk... 2

The role of administrative population-based surveillance data in addressing SMM racial disparities... 4

Epidemiology of SMM and Black-White racial disparities in SMM risk... 7

Opportunities for advancing our understanding of the Black-White disparity in SMM risk... 18

Specific dissertation aims... 18

Dissertation structure... 19

Chapter 2: Study population and data sources... 20

Study population... 20

Georgia hospital discharge records... 21

Georgia vital statistics records: birth and fetal death certificates... 21

Hospital discharge and vital statistics record linkage... 22

Identification of maternal race and ethnicity... 26

Data security and confidentiality... 26

Ethics... 27

Area-level data... 27

Chapter 3: Purpose-built measures: identifying a primary case definition of severe maternal morbidity (SMM) for racial disparities surveillance and research... 28

Abstract... 28

Introduction... 29

Characterizing SMM incidence and Black-White racial disparities in SMM under alternate case definitions... 32

Discussion... 37

Chapter 4: Decomposing the Black-White racial disparity in severe maternal morbidity (SMM) risk: the role of hypertensive disorders of pregnancy... 49

Abstract... 49

Introduction... 50

Methods... 51

Results... 56

Discussion... 60

Conclusions... 63

Chapter 5: Estimating the joint effect of neighborhood relative income inequality and racial segregation on severe maternal morbidity (SMM) risk in Georgia... 64

Abstract... 64

Introduction... 65

Methods... 67

Results... 71

Discussion... 80

Chapter 6: Conclusions... 85

Summary of findings and recommendations... 85

Strengths and limitations... 87

Future directions... 89

Appendices... 91

Identifying SMM in Hospital Discharge Data... 91

Aim 1 Appendix... 94

Aim 2 Appendix... 101

Aim 3 Appendix... 110

References... 122

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