Validation of the Obesity Lifecycle Model Built to Assess the Cost Effectiveness of Novel Therapies in the Management of Obesity

Economic models support healthcare decision makers to efficiently assess value and allocate resources; formal validation is critical to ensure confidence in model outputs. The Obesity Lifecycle Model is a patient-level simulation model capturing natural history, clinical complications, quality-of-life and economic outcomes associated with obesity; however, it has yet to undergo formal external and cross-validation. The aim of this study was to validate the Obesity Lifecyle Model as per best practice guidelines from the Professional Society for Health Economics and Outcomes Research (ISPOR) and the Society for Medical Decision Making (SMDM) Task Force. Relevant data sources and outcomes were identified for all validations. Selected validation studies informed the model to simulate study outcomes. The model was populated with study characteristics to reproduce studies used in model development (dependent validation), studies not used in model development (independent validation), or other published models (cross-validation). Accuracy between predicted and observed outcomes was assessed using standard statistical methods and mean error calculations. The model demonstrated overall concordance with observed outcomes, supported by coefficient of determination (R2) and ordinary least squares linear regression line (OLS LRL) estimates generally close to 1.0. Independent validation showed an underprediction for cardiovascular disease (CVD) and mortality with an OLS LRL of 0.9309 and an R2 of 0.8984 across all populations (normoglycaemic/prediabetic populations: OLS LRL = 0.9485, R2 = 0.8854; T2DM populations: OLS LRL = 0.9208, R2 = 0.9068). The Obesity Lifecycle Model demonstrates favourable concordance with observed clinical and quality-of-life outcomes, supporting its use for evaluating obesity-related complications and informing healthcare decision making.