Objective To describe the characteristics, diagnostics, treatment, and outcome of severe acute otitis media (AOM) and acute mastoiditis (AM) caused by group A beta-hemolytic streptococcus (GAS). Study design A retrospective cohort study. Methods The yearly incidence of inpatient care-needing GAS AOM/AM patients in our hospital catchment area between 2002 and 2018 was investigated. A detailed analysis was performed for cases treated during the last GAS epidemic in 2017-2018. Anamnesis, signs and symptoms, pure-tone audiometry results, treatment, complications, and outcome were collected from medical charts. Patients responded to an otology-specific health-related quality of life survey (EOS-16) 1.5 to 3 years after their treatment. Results T...