Core datasets	Features (with approximate volumes)
Annual District Birth Extract	Office for National Statistics (ONS) register of all births in Wales collected from birth registrations. 35,000 births per year, from 2003 to present.
Annual District Death Extract	ONS register of all deaths relating to Welsh residents, including those that died out of Wales, collected from death registrations. 32,000 births per year, from 2003 to present.
Critical Care Dataset	Nation-wide critical care database to monitor quality of service, to drive improvements and policy development, collected and coded at each hospital. 9,000 admissions per year, from April 2006 to May 2016.
Diagnostic and Therapy Services Waiting Times	Waiting times for specified diagnostic and therapy services for the NHS in Wales, submitted by Local Health Boards. 120,000 records per year from October 2005 to May 2016.
Emergency Department	Administrative and clinical information for all NHS Wales Accident and Emergency department attendances, collected and coded at each hospital. 750,000 attendances per year from 2009 to present.
National Community Child Health Database	Birth registration and monitoring of child health examinations and immunisations, bringing together data from local Child Health System databases, held by Local Health Boards. 35,000 births and 500,000 vaccinations per year, from 1987 to present.
Outpatient Dataset	Attendance information for all NHS Wales hospital outpatient appointments, collected from the central PAS (Patient Administrative System). 4,500,000 appointments per year from 2004 to present.
Outpatient Referral	Referral pathways to secondary care, submitted by Local Health Boards. 1,000,000 records per year, from 2009 to Jun 2016.
Patient Episode Database for Wales	NHS Wales hospital admissions comprising attendance and clinical information, diagnoses and operations performed, collected from the central PAS (Patient Administrative System). 950,000 hospital admissions per year, from 1997 to present.
Postponed Admitted Procedures	Information on reason for cancelled admitted procedures, submitted by Local Health Boards. 80,000 records per year, from 2013 to May 2016.
Primary Care GP dataset	Signs, symptoms, test results, diagnoses, prescribed treatment, referrals for specialist treatment and social aspects relating to the patient’s home environment, collected from General Practices. Averaging around 5000 patients per practice, from between January 2000 to October 2014 (depending on practice) to present.
Referral to Treatment Times	Monitoring the 26-week referral to treatment time target, submitted by Local Health Boards. 450,000 records per year, from September 2011 to May 2016.
UK Health Dimensions	NHS related lookup tables, including version 2 and version 3 Read codes, ICD10 codes, cross-coding system mappings, organisational information, and geographic information, from various reference data providers. Comprises thousands of reference tables.
Welsh Demographic Service Dataset	Administrative information about individuals in Wales that use NHS services, drawn from GP practices. Current and past population of Wales, from 1990 to present (approximately 5 million people).