Table 1

Twenty pairs of trusts that most commonly share patients, the record system in use at each trust in pair and total number of patients with recorded encounters at both trusts over study period (shaded where same record system used in both trusts in pair)

Trust A	Trust B	Record system at trust A	Record system at trust B	Patients shared (N)
North Bristol NHS Trust	University Hospitals Bristol NHS Foundation Trust	DXC Technology	System C	180 746
Guy's and St Thomas' NHS Foundation Trust	King's College Hospital NHS Foundation Trust	DXC Technology	Allscripts	161 412
The Newcastle On Tyne Hospitals NHS Foundation Trust	Northumbria Healthcare NHS Foundation Trust	Cerner	Paper records	159 905
Royal Free London NHS Foundation Trust	University College London NHS Foundation Trust	Cerner	GE Healthcare	133 296
The Lewisham And Greenwich NHS Trust	King's College Hospital NHS Foundation Trust	Cerner	Allscripts	124 772
Manchester University NHS Foundation Trust	Salford Royal NHS Foundation Trust	Multiple systems	Allscripts	120 065
Imperial College Healthcare NHS Trust	Chelsea and Westminster Hospital NHS Foundation Trust	Cerner	Cerner	113 199
The Newcastle On Tyne Hospitals NHS Foundation Trust	Gateshead Health NHS Foundation Trust	Cerner	System C	104 068
Barking, Havering and Redbridge University Hospitals NHS Trust	Barts Health NHS Trust	Paper records	Cerner	100 705
London North West Healthcare NHS Trust	Imperial College Healthcare NHS Trust	Multiple systems	Cerner	95 163
Manchester University NHS Foundation Trust	Pennine Acute Hospitals NHS Trust	Multiple systems	Paper records	87 463
Guy's and St Thomas' NHS Foundation Trust	The Lewisham and Greenwich NHS Trust	DXC Technology	Cerner	87 064
The Royal Bournemouth and Christchurch Hospitals NHS Foundation Trust	Poole Hospital NHS Foundation Trust	EMIS Health	Graphnet	86 538
University Hospital Birmingham NHS Foundation Trust	Sandwell and West Birmingham Hospitals NHS Trust	In-house Development	Cerner	83 653
North Middlesex University Hospital NHS Trust	Royal Free London NHS Foundation Trust	Paper records	Cerner	83 566
University Hospital Birmingham NHS Foundation Trust	Heart of England NHS Foundation Trust	In-house Development	In-house Development	81 363
Royal Liverpool and Broadgreen University Hospitals NHS Trust	Aintree University Hospital NHS Foundation Trust	Multiple systems	Multiple systems	80 522
North Tees and Hartlepool NHS Foundation Trust	South Tees Hospitals NHS Foundation Trust	Intersystems	Paper records	80 322
Barts Health NHS Trust	Homerton University Hospital NHS Foundation Trust	Cerner	Cerner	74 741
St George's University Hospitals NHS Foundation Trust	Epsom and St Helier University Hospitals NHS Trust	Cerner	DXC Technology	69 435

NHS, National Health Service.