Diverging Neisseria gonorrhoeae Morbidity in Non-Hispanic Black and White Females: Application of Group-Based Trajectory Modeling to Trends in County-Level Morbidity 2003-2018

National trends in gonorrhea rates may obscure informative local variations in morbidity. We used group-based trajectory models to identify groups of counties with similar gonorrhea rate trajectories among non-Hispanic White (NHW) and non-Hispanic Black (NHB) females using county-level data on gonorrhea cases in US females from 2003 to 2018. We assessed models with 1-15 groups and selected final models based on fit statistics and identification of divergent trajectory groups with distinct intercepts and/or slopes. We mapped counties by assigned trajectory group and examined the association of county characteristics with group membership. We identified 7 distinct gonorrhea trajectory groups for NHW females and 9 distinct trajectory groups for NHB females. All identified groups for NHW female morbidity experienced increasing gonorrhea rates with a limited range (11.6-183.3/100,000 NHW females in 2018); trajectories of NHB female morbidity varied widely in rates (146.6-966.0/1000 NHB females in 2018) and included 3 groups of counties that experienced a net decline in gonorrhea rates. Counties with higher NHW female morbidity had lower adult sex ratios, lower health insurance coverage, and lower marital rates among NHW adults. Counties with higher NHB female morbidity were more urban, experienced higher rates of poverty, and had lower rates of marriage among NHB adults. Morbidity patterns did not always follow geographic proximity, which could be explained by variation in social determinants of health. Our results demonstrated a highly heterogenous gonorrhea epidemic among NHW and NHB US females, which should prompt further analysis into the differential drivers of gonorrhea morbidity.

Automated summary

This study used group-based trajectory models to identify the trajectories of gonorrhea rates among non-Hispanic White (NHW) and non-Hispanic Black (NHB) females in the US. The study found that gonorrhea rates increased among NHW females and varied among NHB females, including counties with declining rates. The study also found that the patterns of morbidity did not always follow geographic proximity, suggesting the role of social determinants of health.