NELA Risk Adjustment Model - Background:
The NELA risk adjustment model was developed to facilitate casemix-adjusted comparison of emergency laparotomy 30-day mortality rates between hospitals. The rationale for the model and its development are documented in Eugene et al (2018).
The risk model was updated because, since its development, (1) the national mortality rate after emergency laparotomy has fallen, and (2) data quality in NELA has increased. The updated risk model provides an improved prediction of patients' mortality risk.
The updated model assumes a slightly lower baseline mortality than the original model. The variables that predict mortality risk have not been changed, only the relative weights (coefficients) of their contributions to the risk prediction.
The original model used data from NELA Audit Years 1 and 2, this update of the models' coefficients uses records from NELA Audit Years 4-6, and went live in October 2020.
The coefficients have been updated in the web-based
NELA risk calculator and within the NELA data collection webtool. We do not know if other risk calculator apps have updated the coefficients. We therefore advise that clinicians should only use the above links when calculating predicted risk for patients undergoing emergency laparotomy. All future NELA metrics will be based on the updated risk coefficients.
Further information on this update can be found in the document below: