The Current Epidemiology of Injecting Drug Use-Associated Infective Endocarditis in Victoria, Australia in the Midst of Increasing Crystal Methamphetamine Use.

BACKGROUND

Infective endocarditis (IE) is associated with significant mortality and morbidity despite recent advances in management. Injecting drug use (IDU) remains an important risk factor. Our aim was to evaluate the rates and patient demographics of IE and injecting drug use-associated infective endocarditis (IDU-IE) in Victoria from 2009 to 2014.

METHODS

The Victorian Admitted Episode Dataset (VAED) was used to identify a population-based cohort with a diagnosis of IE and IDU-IE between 2009 and 2014 in Victoria. Incidence rates were calculated per 100,000 people/year. Rate ratios were calculated using Poisson distributions, and chi squared (χ) test for trend were calculated to identify significant linear trends.

RESULTS

The incidence rate of IE overall has risen significantly from 11.09 to 13.56 per 100,000 people/year from 2009 to 2014 (rate ratio 1.22, 95% confidence interval (CI) 1.10, 1.36, p<0.001). The incidence of IDU-IE has also risen significantly from 0.92 to 1.76 per 100,000 people/year from 2009 to 2014 (rate ratio 1.93, 95% CI 1.28, 2.90, p=0.002). The chi squared (χ) test for trend of both IE and IDU-IE also suggests a statistically significant linear trend (p=0.0015 and 0.005 respectively). Descriptive epidemiology revealed men are twice as likely to be affected by IE overall. The elderly were found to be the most affected by IE overall (ages 75 to 79 years) with IDU-IE affecting a much younger age group (ages 30 to 34 years). Validation of hospital coding for IDU-IE was shown to have sensitivity of 77.2% (95% CI 64.8, 86.2).

CONCLUSIONS

This study identified that from 2009 to 2014 there has been a significant increase in incidence of both IE overall and IDU-IE in Victoria. These findings highlight the need for the planning of targeted interventions to mitigate the incidence of disease.