The proportion of people waiting more than four hours to be seen in A&E departments has typically been higher in Wales than either England or Scotland over the past decade, analysis shows.
All three nations have recorded a steady rise in recent years in the percentage of people not seen within four hours, including a steep jump since the Covid-19 pandemic.
But levels were higher in Wales than England and Scotland in every month from January 2013 to August 2022 and in most months since then, with England taking the top spot on only a few occasions.
The figures have been published in a report by the Office for National Statistics (ONS) which makes comparisons for the first time between certain types of health data across the country.
Health policy in the UK is not co-ordinated centrally but is instead devolved to each of the four nations, which then report data separately on topics such as the performance of hospitals.
Waiting times at Accident and Emergency (A&E) departments represent an area where comparisons can be made between England, Wales and Scotland, because the data is collected in broadly the same way, the ONS said.
The report shows that all three nations have seen a general upward trend in the proportion of A&E attendances waiting longer than four hours, with Wales rising from 15.6% in January 2013 to a peak of 45.8% in December 2022, before falling to 40.5% in September 2023.
England started at a lower point than Wales, at just 8.1% of A&E attendances in January 2013, but recorded a higher peak in December 2022 of 50.4%, before dropping to 42.4% in September 2023.
The figures for Scotland run from 11.7% in January 2013 to a peak of 41.7% in December 2022, with 33.5% for September 2023.
Scotland has typically recorded a lower proportion of people waiting more than four hours in A&E departments than England and Wales across much of the period.
The figures may reflect a number of factors, including the ease of access to A&E departments and the services offered, population differences such as age and levels of deprivation, and the mix of healthcare facilities available, the ONS said.
The data covers attendances at A&E departments providing 24-hour consultant-led services, which are equipped for the treatment of serious and life-threatening injuries.
These are called Type 1 Departments in England, Emergency Departments in Scotland and Major Emergency Departments in Wales.
Health services operating in the three nations all follow policy guidance that states every effort should be made to transfer or admit patients, who require a period of observation, assessment, or recovery, to suitable facilities where available – at which point the waiting time “clock” stops.
No such policy exists in Northern Ireland, which is why A&E waiting times cannot be directly compared with the rest of the UK.
Becky Tinsley, a deputy director at the ONS, said the report was intended to “make it easier to understand health data from across the UK” and help create “a joined-up statistical picture”.
She added: “This doesn’t mean that we’re developing a one-size-fits-all approach to data across the four nations.
“We understand that there are differences in policy, infrastructure and processes which may impact data collection and our ability to make comparisons.
“There are also other factors that are important to consider, like differences in the age of each of the countries’ populations, which impact people’s health and result in different demands on the health service.
“By considering this wider context, we can better understand the differences and similarities in statistical outputs across the nations, and the areas they describe.”
The ONS also looked at the overall number of A&E attendances across the UK, which can be broadly compared between all four nations – including Northern Ireland – as it is less affected by differences in how the data is collected.
The report found that Northern Ireland has had “a consistently higher number” of A&E attendances per 1,000 population compared with other nations across the past decade, with 29 per 1,000 in September 2023, above the equivalent figures for Scotland (21), Wales (21) and England (14).
The difference in attendances can be influenced by “many factors” including increases in population, rates of disability or long-term illnesses, aging population, policy changes and the ease of access to other types of health services, the ONS added.