Trends in the utilisation of emergency departments in California, 2005–2015: a retrospective analysis

ObjectiveTo examine current trends in the characteristics of patients visiting California emergency departments (EDs) in order to better direct the allocation of acute care resources.DesignA retrospective study.SettingWe analysed ED utilisation trends between 2005 and 2015 in California using non-public patient data from California’s Office of Statewide Health Planning and Development.ParticipantsWe included all ED visits in California from 2005 to 2015.Primary and secondary outcome measuresWe analysed ED visits and visit rates by age, sex, race/ethnicity, payer and urban/rural trends. We further examined age, sex, race/ethnicity and urban/rural trends within each payer group for a more granular picture of the patient population. Additionally, we looked at the proportion of patients admitted from the ED and distribution of diagnoses.ResultsBetween 2005 and 2015, the annual number of ED visits increased from 10.2 to 14.2 million in California. ED visit rates increased by 27.8% (p