Amoebic liver abscess in USA: a population-based study of incidence, temporal trends and mortality.

Background: Amoebic liver abscess (ALA) may be associated with significant morbidity and mortality, but nationwide American data is unavailable. Our objective was to describe ALA epidemiology and outcomes in USA from a population-based perspective.

Methods: Patients hospitalized with ALA between 1993 and 2007 were identified using the Nationwide Inpatient Sample. Patient characteristics, interventions and outcomes including mortality were determined. The annual incidence of ALA and temporal trends were determined using the negative binomial regression models.

Results: Between 1993 and 2007, 848 hospitalizations for ALA, corresponding to ∼4100 hospitalizations nationwide, were identified. The annual incidence was 1.38 per million population with a 2.4% [95% confidence interval (CI) 0-4.8%; P=0.06] average annual decline during this study. Most patients were hospitalized in western (54%) and southern states (27%), and 48% were Hispanic. Males (incidence rate ratio vs. females: 4.53; 95% CI 4.19-4.90) had the highest incidence rates. Percutaneous and surgical drainage was required in 48 and 7% of patients respectively. Although length of stay [median, 6 days; interquartile range (IQR) 4-10] and hospital charges (US$25,345; IQR US$15,030-42, 275) were substantial, in-hospital mortality was rare (0.8%). Females [odds ratio (OR) 6.12; CI 1.39-26.8], patients ≥ 60 years (OR 13.3; 95% CI 2.5-71.5), and those with ≥ 3 comorbidities (OR 5.80; 95% CI 1.30-25.8), particularly malnutrition, had an increased risk of death.

Conclusions: ALA is rare and the incidence has decreased in USA. Young, Hispanic males in southwestern states are most frequently affected. Mortality caused by ALA is lower than what was reported previously.