The complexity of acute mastoiditis in Swedish children

Acute mastoiditis (AM) is a rare complication to acute otitis media (AOM) in children. Population-based studies are useful for establishing adequate treatment strategies and to evaluate the effects related to the introduction of the pneumococcal conjugate vaccine (PCV) in 2007. Previous reports however report on an overdiagnosis of AM, warranting the need for validity assessment. The aim of the present study was to assess the validity of ICD-10 diagnoses of AM and to address the differential diagnoses. Further, we aimed to map the incidence of AM over time and to specifically map the cases with delayed recovery.

A retrospective study of all hospitalized pediatric cases in Region Stockholm, Sweden, diagnosed as mastoiditis between 2003 and 2019. Case records were manually reviewed to verify the diagnosis of AM and schematically collect data.

Out of 275 episodes with an ICD-10 diagnosis of AM, 193 were verified and 74 (26.9 %) had other diagnoses. The incidence of AM among children 0-1 years decreased since the introduction of PCV. Thirty-one cases displayed a delayed clinical recovery, including three cases with sigmoid sinus thrombosis. Children with a differential diagnosis, displayed mostly skin infections or otitis externa, and were significantly older than children with AM.

Chart validity assessment is needed in larger retrospective studies on AM where cases are identified using ICD-10 diagnosis code. The introduction of PCV has decreased the cases of AM in children <2 years.