Development of the national bariatric prioritization tool in Aotearoa New Zealand

Bariatric surgery is a proven effective method of reducing obesity and reversing or preventing obesity-related comorbidities. The aim of this study is to describe the development of a tool to assist with the prioritization of patients with obesity for bariatric surgery. The tool would meet the criteria for being evidence-based, fair, implementable and transparent.

The development of the tool involved a validated step-by-step process based on the consensus of clinical judgement of the New Zealand Ministry of Health working party. The process involved elicitation of criteria, clinical ranking of vignettes and creation of weightings using the 1000Minds® tool. The concurrent validity was tested by comparing tool rankings of vignettes to clinical judgement rankings.

Four major criteria (impact on life, likelihood of achieving maximum benefit with respect to control of diabetes, duration of benefit and surgical risk) are used to characterize the need and potential to benefit. The impact on life criterion has the largest weighting (up to 44.3%). There was good concurrent validity with a correlation coefficient r = 0.67.

The tool as presented is evidence-based, transparent and internally valid. The next step is to assess the predictive validity of the tool using real patient data to evaluate the effectiveness of the tool and determine what modifications may be required.