BackgroundIn recent years, a number of emergency departments (EDs) have closed or have been replaced by another facility such as an urgent care centre. With further reorganisation of EDs expected, this study aimed to provide research evidence to inform the public, the NHS and policy-makers when considering local closures.ObjectiveTo understand the impact of ED closures/downgrades on populations and emergency care providers.DesignA controlled interrupted time series of monthly data to assess changes in the patterns of mortality in local populations and changes in local emergency care service activity and performance, following the closure of type 1 EDs.SettingThe populations of interest were in the resident catchment areas of five EDs that closed between 2009 and 2011 (in Newark, Hemel Hempstead, Bishop Auckland, Hartlepool and Rochdale) and of five control areas.Main outcome measuresThe primary outcome measures were ambulance service incident volumes and times, the number of emergency and urgent care attendances at EDs, the number of emergency hospital admissions, mortality, and case fatality ratios.Data sourcesData were sourced from the Office for National Statistics, Hospital Episode Statistics (HES) accident and emergency, HES admitted patient care and ambulance service computer-aided dispatch records.ResultsThere was significant heterogeneity among sites in the results for most of the outcome measures, but the overall findings were as follows: there is evidence of an increase, on average, in the total number of incidents attended by an ambulance following 999 calls, and those categorised as potentially serious emergency incidents; there is no statistically reliable evidence of changes in the number of attendances at emergency or urgent care services or emergency hospital admissions; there is no statistically reliable evidence of any change in the number of deaths from a set of emergency conditions following the ED closure in any site, although, on average, there was a small increase in an indicator of the ‘risk of death’ in the closure areas compared with the control areas.LimitationsUnavailable or unreliable data hindered some of the analysis regarding ED and ambulance service performance.ConclusionsOverall, across the five areas studied, there was no statistically reliable evidence that the reorganisation of emergency care was associated with an increase in population mortality. This suggests that any negative effects caused by increased journey time to the ED can be offset by other factors; for example, if other new services are introduced and care becomes more effective than it used to be, or if the care received at the now-nearest hospital is more effective than that provided at the hospital where the ED closed. However, there may be implications of reorganisation for NHS emergency care providers, with ambulance services appearing to experience a greater burden.Future workUnderstanding why effects vary between sites is necessary. It is also necessary to understand the impact on patient experience. Economic evaluation to understand the cost implications of such reorganisation is also desirable.FundingThe National Institute for Health Research Health Services and Delivery Research programme.