**Primary outcome measures: Synthetic Control (ITS) Study** |

Rate of admissions to mental health trust adult inpatient wards per 1000 trust catchment population | Rate of ED psychiatric presentations per 1000 trust catchment population) |

**Primary outcome measures: ITS Study** |

Rate of informal admissions to mental health trust adult inpatient wards per 1000 trust catchment population | Rate of ED psychiatric presentations per 1000 trust catchment population) |

**Secondary outcome measures (both studies)** |

**Mental health trust** | **Acute trust** |

Rate of inpatient admissions per 1000 trust catchment population | Proportion of 4-h psychiatric ED breaches (denominator psychiatric ED presentations) |

Proportion of 0–5 day inpatient admissions (denominator total inpatient admissions) | Average length of psychiatric ED wait |

Average length of inpatient stay (bed days) | Proportion of psychiatric ED 12 h trolley waits (denominator psychiatric ED presentations) |

Proportion of compulsory admissions (denominator total admissions) | Proportion of psychiatric ED admissions admitted to an acute bed (denominator psychiatric ED presentations) |

Proportion of psychiatric liaison episodes at the ED (denominator psychiatric ED presentations) | Proportion of psychiatric ED arrivals by ambulance or police (denominator psychiatric ED presentations) |

**ITS only outcomes:** |

Daily mean occupied bed days (denominator size of trust catchment population) | |

Proportion of out of area admissions (from the site MH trust to other MH trust or private provider) (denominator total inpatient admissions) | |