The incidence of infective endocarditis (IE) has increased since 1970 and Staphylococcus aureus IE has been found to be seasonally dependent, according to the results of a study published in Open Forum Infectious Diseases.

A population-based review of adults from a single county in Minnesota was conducted. Definite or possible cases of IE were identified using the Rochester Epidemiology Project from January 1, 1970, through December 31, 2018.

Within this time period, 269 incident cases of IE were observed. After adjusting for age and sex, the overall incidence rate of IE was 7.9 cases per 100,000 person-years (95% CI, 7.0-8.9), and men were found to have higher rates of IE than women at 12.1 (95% CI, 10.3-13.9) vs 4.5 (95% CI, 3.6-5.5), respectively.


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S aureus and viridans group streptococci (VGS) were the most common pathogens associated with IE, with both having incidence rates of 2.4 (95% CI, 1.9-2.9). Enterococci and coagulase-negative staphylococci IE incidence rates were 0.9 (95% CI, 0.6-1.2) and 0.7 (95% CI, 0.5-1.0), respectively.

The temporal trend of IE incidence was dependent on age, sex, and season with model estimated trends showing highly significant effects of age and sex on IE incidence (both P <.001). There was no evidence for seasonal effect overall (P =.271) or differentially by calendar year (P =.200 for time × season interaction).

A 39% increase in incidence (average incidence ratio, 1.39; 95% CI, 1.03-1.86) was associated with an interquartile range (IQR) increase in calendar year (from 1992 to 2014), which according to investigators was consistent with the observations of an increasing temporal trend.

Separating the models of incidence by pathogen found the trend of increasing S aureus occurred in winter months. Between the years of 1992 and 2014, there was an approximately 28-fold increase in incidence in winter and only 0.7-, 3.2-, and 1.4-fold increases in spring, summer, and fall, respectively.

Among the other pathogens, only enterococci IE had a significant increasing temporal trend in incidence (P =.001). A nearly 3-fold increase in IE incidence (aIR, 2.90; 95% CI, 1.53-5.50) equal to approximately 5.0% per year was associated with an IQR increase in the calendar year (from 1992 to 2014).

A subset analysis assessing the impact of the American Heart Association prevention guidelines implemented in 2007 found no evidence of a statistically significant increase in VGS IE incidence with regard to the changes. Between 1996 and 2018, 45 cases of VGS IE were identified for an age- and sex-adjusted incidence rate of 2.1 (95% CI, 1.5-2.8) per 100,000 person-years.

According to the investigators, this is the only population cohort study of IE incidence to span 5 decades. They report a significant increase in overall IE from 1970 to 2018 with S aureus remaining the most common pathogen and the only pathogen showing signs of seasonal variation.

When averaging underlying seasonal effects, the investigators identified an increasing temporal trend in S aureus occurring mostly over the final 2 decades. This may be in part due to increased health care-related exposures, such as implanted mechanical and bioprosthetic cardiac valves, hemodialysis, and an aging population, requiring more intervention. The investigators highlighted the need for epidemiologic population-based studies to monitor and clarify these trends.

Disclosure: Some study authors declared affiliations with the biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

Reference

DeSimone DC, Lahr BD, Anavekar N, et al. Temporal trends of infective endocarditis in Olmsted County, Minnesota, between 1970 and 2018: a population-based analysis. Open Forum Infect Dis. 2021;8(3):ofab038. doi:10.1093/ofid/ofab038