Ethics
This study used data from the Hospital Episode Statistics (HES) database
for England. The HES database is collected by NHS Digital for all
patients seen at hospitals in England. Permission to access the database
was granted to the GIRFT programme working within the NHS Improvement
information technology environment. Consent from individuals involved in
this study was not required. The presentation of data follows current
NHS Digital guidance for use of HES data for research
purposes.5