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Multi-Centre Evaluation of Renal Impairment in Thoracic Surgery (MERITS)

BACKGROUND: In thoracic surgery, unit-based mortality has been used as outcome measure. However, with improved case selection and peri-operative care, mortality has become very low, limiting it’s use as a comparative performance measure. There is a need to identify additional outcome measures that have face validity, are reliable, associated with meaningful outcomes and show variation. We propose acute kidney injury (AKI).To evaluate this we developed, piloted and undertook a multi-centre study of AKI post-thoracic surgery (MERITS). 
 
METHODS: Retrospective data on renal function post-thoracic surgery was collected by 17 thoracic surgery units across the UK for a 1-year period between 1st April-2016 and 31st March-2017. Data collection was supported by SCTS STUDENTS, the student wing of our professional society. 
 
FINDINGS: 17 of 35 UK centres provided data on 15154 patients. Unit operative volumes ranged from 304-2416 patients per year. AKI was diagnosed in 1090 patients (7.2%) within 7 days of thoracic surgery with AKI stage 1 (4.8%), stage 2 (1.7%) and stage 3 (0.7%). There was a statistically significant variation in AKI incidence between units from 3.1 to 16.1% (p<0.05). Significant differences between non-AKI and AKI were found in post-operative length of stay (3 vs 7 days, p<0.001), 30-day mortality (1.6 vs 9%, p<0.001), 90-day mortality (4.4 v 14.7%, p<0.001) and 1-year mortality (12.2 vs 23.1%, p<0.001). 
 
INTERPRETATION: Following thoracic surgery, AKI incidence ranged from 3.1% to 16.1% between units (p<0.05). There are also important associations between AKI and both length of stay and mortality. Therefore, we propose that AKI is a suitable comparative and absolute quality measure in thoracic surgery. Reducing rates of AKI may bring about important improvements in patient outcomes, length of hospital stay and reduce costs. 
 
FUNDING: Statistical support was provided from the MRC Biostatistics Unit Cambridge through an allowance from Royal Papworth Hospital. No additional funds were used, and the work was done on a voluntary basis by all the collaborators. 
 
DECLRATION OF INTERESTS: None declared. 
 
ETHICS APPROVAL STATEMENT: The project was approved by the Clinical Audit and Effectiveness Department at the study centre which was Royal Papworth Hospital, Cambridge (Registration Number: 1702) with a waiver for the need for patient consent and was approved as a multi-centre audit. This study was then registered as a clinical audit at each of the collaborating hospitals.