Among the oceans of data washing around the NHS, it is striking that government has avoided collecting one of the most illuminating sets of figures - comparisons between England, Scotland, Wales and Northern Ireland.

The four provide a fascinating laboratory for comparing systems, inputs and outcomes. For a geographically small country the UK provides sharp contrasts in healthcare policy, from England’s market and target culture to Scotland’s integrated system for purchasing and providing secondary and primary care. But until today comparisons of the impact on patients have been elusive.

To rectify this data deficit, HSJ and healthcare information providers CHKS have analysed key indicators across the four systems. We have uncovered dramatic differences which require explanation. (See Huge contrasts found between UK nations and National service: health policy performance across the UK)

For example, Northern Ireland has a high rate of elective admissions, while England’s rate is growing fast. Are Northern Ireland surgeons keener to cut patients open? Is payment by results providing an incentive for more patients in England to be sucked into surgery?

The percentage of emergency admissions discharged on the same day is rising sharply in both England and Wales but falling in Scotland from an already low rate. Are patients there being kept overnight unnecessarily because of a lack of incentives to use beds efficiently? Or should there be more concern that patients discharged in England are far more likely to require emergency readmission than those in Northern Ireland? These are just a handful of the questions the four nations comparisons raise.

Publish everything

Ministers are pushing the NHS to publish everything from patient satisfaction scores to death rates. It is a pity those in charge of the various health systems do not have the courage to expose themselves to similar scrutiny by collecting comparisons across the four parts of the UK.

Managers, practitioners, opinion formers and governments need to understand and debate these differences. This week, HSJand CHKS hope to trigger a debate which will help the NHS learn from the worst and best.