Despite declines in disability-adjusted life years (DALYs) and mortality rates from myocarditis globally from 1990 to 2023, its incidence and prevalence remained stable, suggesting improvements in disease outcomes over time, according to a study using data from the GBD (Global Burden of Disease, Injuries, and Risk Factors Study) 2023 and published Sept. 2 in JACC. Absolute burden continues to increase due to population growth and aging, with substantial disparities persisting across age groups and socio-demographic index (SDI) levels.

The GBD 2023 Myocarditis Collaborators used health facility and vital registration data to estimate myocarditis prevalence, incidence, DALYs, mortality and mortality-to-incidence ratios (MIRs) by country, age, sex and SDI quintile. The analysis also estimated HF attributable to myocarditis and used MIRs to compare mortality burden with disease incidence at the population level.

Myocarditis mortality was modeled using International Classification of Diseases-coded vital registration records in a cause of death ensemble model.

In 2023, the global age-standardized rates of prevalence, incidence, DALY and mortality of myocarditis were 4.8, 12.5, 8.4 and 0.21 per 100,000 population, respectively. Although global age-standardized prevalence and incidence rates remained stable between 1990 and 2023, the number of new myocarditis cases increased by 54%, rising from 0.67 million to 1.04 million.

Additionally, age-standardized DALYs and mortality rates from myocarditis decreased substantially, by 62% and 60%, respectively, suggesting significant improvements in survival and disease outcomes. MIRs also decreased across all age groups, although they remained highest among the youngest and oldest populations, with the ratio in those <5 years of age declining from 18% in 1990 to 6% in 2023.

Patterns by SDI level showed persistent disparities despite overall improvement. Incidence rates were stable across all SDI quintiles, while mortality rates declined in every quintile and were lowest in high-SDI regions. The MIR also improved, decreasing from 2.3 in 1990 to 1.3 in 2023. In 2023, myocarditis prevalence was highest in high-SDI regions and lowest in low-middle-SDI regions, a pattern the authors suggest may reflect differences in health care access and diagnostic capacity. HF due to myocarditis became less common between 1990 and 2023, but the burden remained highest among children under 5 years and adults over 75 years.

“These findings highlight the need for targeted strategies to improve early diagnosis and reduce the burden of myocarditis, particularly in vulnerable populations and lower-resource settings, while being interpreted in the context of evolving diagnostic and coding practices,” write the authors.