Fatal inflammation: understanding meningitis mortality in the United States (1999-2020)

Meningitis, an inflammatory condition that affects the meninges, has reported an increase in cases between 2006 and 2016. While in well-resourced settings, the incidence of acute bacterial meningitis has declined to below 0.5-1.5 cases per 100,000 population. Overall, late excess mortality following meningitis is highest within the first two years after discharge, particularly affecting patients aged 30-60 years. This research seeks to analyse these trends and investigate potential disparities in mortality rates based on demographic variables between 1999 and 2020. By quantifying high-risk populations and regional differences, the findings provide evidence to guide targeted public health interventions and resource allocation.

This retrospective observational study used CDC WONDER data (1999-2020) to analyse mortality trends for individuals aged 1-85 + years. Deaths related to meningitis were identified using ICD-10 codes A17.0, A32.1, A39.0, A87.0, A87.1, A87.2, A87.8, A87.9, B00.3, B01.0, B02.1, B05.1, B26.1, B37.5, B38.4, G00.0, G00.1, G00.2, G00.3, G00.8, G00.9, G03.0, G03.1, G03.2, G03.8, G03.9. Crude mortality rates and age-adjusted mortality rates (AAMRs) were calculated. Temporal trends and significant changes in mortality trajectories were assessed using Joinpoint regression analysis, which estimated annual percentage changes (APCs) and identified statistically significant inflection points. Mortality patterns were further stratified by sex, race or ethnicity, census region, state, and urban-rural classification.

Between 1999 and 2020, meningitis-related AAMRs in the United States declined from 8.43 to 3.88 per 1,000,000 population, with the steepest decrease between 1999 and 2012 before stabilising thereafter. Males consistently showed higher mortality (AAMR 5.79) compared to females (AAMR 4.53), though both declined substantially over the study period. Non-Hispanic (NH) Black individuals exhibited the highest AAMRs (8.59), followed by Hispanics (4.81), NH Whites (4.64), and NH Asians or Pacific Islanders (3.58). Geographically, the West (5.35) and South (5.33) had the greatest burden, while the Northeast (4.69) and Midwest (4.81) reported lower rates. State-level variation ranged from 8.85 per 1,000,000 in the District of Columbia to 3.52 per 1,000,000 in Delaware, with higher mortality in non-metropolitan areas than metropolitan ones.

This study provides a comprehensive analysis of meningitis-related mortality trends in the United States from 1999 to 2020, highlighting significant declines in AAMRs across demographic groups, regions, and urbanisation levels. Despite the overall decline, the stabilisation of AAMRs in the last decade suggests a plateau in progress, necessitating further investigation into the underlying factors. Thus, targeted interventions to enhance the prevention, control, and management of risk factors might be required to achieve lasting change.