Table 1.

List of databases used and their description

Database	Description
Annual District Death Extract	Collected from the Office for National Statistics, containing death registration information, relating to Welsh residents including those who died outside of Wales.
Outpatient Dataset for Wales	Administrative and clinical data obtained from outpatient appointments in Wales.
Patient Episode Database for Wales	Administrative and clinical data for all hospital admissions, including diagnosis and operations performed.
Welsh Cancer Intelligence and Surveillance Unit	The national cancer registry for Wales. Captures all Welsh patients with melanoma from a number of sources: multidisciplinary team data, pathology data, other routine data sources in Wales and the English cancer registry.
Welsh Longitudinal General Practice	Administrative and clinical data from all patient visits to a general practitioner.
Welsh Demographic Service Dataset	Administrative data about individuals resident or registered in Wales that have used National Health Service services.