Objectives To evaluate the incidence of acute mastoiditis in children in the United States over the years 1997 through 2006 and to explore possible explanations for the conflicting conclusions of recent studies of this topic.
Design Comparison of periodic incidence over a decade.
Setting Academic and community, general, and pediatric specialty hospitals in the United States.
Patients Children younger than 18 years in the United States treated and discharged with a diagnosis of acute mastoiditis during the years 1997 through 2006.
Main Outcome Measures To compare true incidence of acute mastoiditis in the pediatric population of the United States, data from Healthcare Costs and Utilization Project–Kids' Inpatient Database (HCUP-KID) was examined for nationally weighted estimates of hospital discharges, demographics (age and sex), hospital characteristics, and insurance characteristics.
Results No significant change was found in the incidence of acute mastoiditis over the study period (from 1.88 to 1.62 per 100 000 person-years) (regression coefficient −0.024 [95% CI, −0.110 to 0.024]) (P = .37). Children admitted with acute mastoiditis had an increased odds of presenting to a teaching hospital (odds ratio [OR], 1.38 [95% CI, 1.31-1.45]) (P < .001), a children's hospital (OR, 1.08 [95% CI, 1.03-1.14]) (P = .001), and to a metropolitan location (OR, 1.10 [95% CI, 1.02-1.18]) (P = .016) over calendar time.
Conclusions The incidence of acute mastoiditis in the United States is not increasing. The changes in hospital factors identified over the course of this study may explain the perception of increased incidence identified in studies that have not used population-level data.