The Irish Surgical Outcomes Study' (ISOS) published this weekend in an international medical journal, The Lancet, has found Ireland has a surgical mortality rate of 2.5% for elective non-cardiac surgery; this figure is in line with European levels. The ISOS is an Irish rebuttal study to the European Surgical Outcomes Study (EuSOS) which studied 28 European countries and was published in the Lancet in September 2012. The EuSOS reported a rate of 6.4% mortality rate for Ireland. This finding was seriously concerning to the Royal College of Surgeons in Ireland (RCSI), as the national body responsible for education, training and advocacy of surgery in Ireland.

When the EuSOS data was not made available by the UK based authors to enable a clearer understanding of the potential areas of concern (as would be expected in the international research community), RCSI commissioned a replication study (ISOS) to validate the data and the methods of data collection. The ISOS was a retrospective study examining patients' charts for the same time period (4-11 April 2011) as the original study in the same 17 hospitals with the same data collection tools from the EuSOS in order to validate the findings. If the findings were replicated, then there would clearly be a serious need to reappraise surgical practise in Ireland - if not, then the inaccurate representation of Irish surgical outcomes needed to be addressed.

Using the same methodology, time period and hospitals as the European Surgical Outcomes Study, the Irish Surgical Outcomes Study (ISOS) found 25% more eligible patients, a 39% lower critical care admission rate and 68% lower mortality rate than that reported by EuSOS.

In the ISOS, 1071 patients were identified compared to 856 in the EuSOS. 56 patients (5.3%) were admitted to critical care in the ISOS compared to 66 (7.7%) in the EuSOS. The ISOS identified 27 patients who died (2.5%) compared to 55 (6.4%) in the EuSOS.

Professor Patrick Broe, RCSI President, said: "As a College, RCSI needed to assess the challenging data reported in the European Surgical Outcomes Study - either to validate the data and take swift action if needed to ensure Irish patients have surgical outcomes equivalent to their European counterparts, or to refute the findings from a study where access to the data to independently verify it and how it was collected was not given.

"The findings from the Irish Surgical Outcomes Study are considerably lower than the figures reported in the European Surgical Outcomes Study. The Irish Surgical Outcomes Study found that the rate of patient deaths is comparable to international levels.

"As the national training body for surgery in Ireland, RCSI has a responsibility to advocate for the highest standard of surgical care for the people of Ireland. Morbidity and mortality data is collated in every hospital in Ireland on a monthly basis and these outcomes are monitored against international norms. Whilst we can never be complacent about mortality rates and we must always remain vigilant, the ISOS results are in line with the data reported through the hospital systems and these results are reassuring to both patients and practitioners in Ireland."

The ISOS was conducted on behalf of the Council of RCSI. The steering committee comprised Professor Patrick Broe (President, Royal College of Surgeons in Ireland (RCSI)); Dr Ellen O'Sullivan (President, College of Anaesthetists of Ireland); Dr Philip Crowley, (National Director of Quality and Patient Safety, Health Services Executive (HSE); Professor Ronan O'Connell, (School of Medicine and Medical Sciences, University College Dublin); Dr Gavin Lavery, (Clinical Director, Health and Social Care (HSC),Safety Forum); Professor Cathal Kelly, (CEO, RCSI, ISOS Chair); Professor Anne Hickey, (Head of Psychology Department RCSI); Ms Deirdre Hyland, (RCSI, Clinical Research Centre, Beaumont Hospital); Professor Hannah McGee, (Dean of the Faculty of Medicine and Health Sciences, RCSI); Professor Ray Stallings (Director of Research, RCSI). Study authors were Dr Sally Doherty, Professor Ronan Conroy and Dr Hilary Dunne, on behalf of the RCSI).

Table 1 - comparative results

	European Surgical Outcomes Study Results (Irish Figures)	Irish Surgical Outcomes Study Results
Patients Identified	856	1071
Median Hospital Stay (IQ)	3 (1 to 6)	3 (1 to 7)
Admitted to Critical Care	66	56
Percentage admitted to critical care (95% CI)	7.7% (5.9% - 9.5%)	5.3% (4.0% - 6.9%)
Number died in hospital	55	27
Percentage died in hospital	6.4% (4.8% - 8.1%)	2.5% (1.9 - 3.4%)
Unadjusted Odds Ratio (UK as reference)	1.86 (1.39 - 2.49)	0.70 (0.45 - 1.04)