Aims: Socioeconomic inequalities exist across the colorectal cancer (CRC) screening pathway in Australia, including screening participation, diagnostic follow-up and CRC outcomes. We aimed to evaluate the health equity impact of the NBCSP by quantifying how screening benefits are distributed across socioeconomic status (SES) groups, identifying the key drivers of inequalities in CRC outcomes, and assessing how alternative screening strategies perform when both equity and efficiency are considered.
Methods: The Policy1-Bowel microsimulation model was recalibrated for each SES group to reproduce subgroup-specific CRC outcomes in a simulated Australian birth cohort. Scenarios included no screening, current NBCSP practice based on observed participation and follow-up rates, and participation improvement strategies with proportional increases applied equally across SES groups or greater increases among groups with lower baseline participation. Health outcomes, costs and benefit were estimated by SES group. Inequalities in outcomes were decomposed to quantify the contributions from underlying disease risk, screening participation, and diagnostic follow-up. The equity-weighted net health benefit of screening was estimated across a range of inequality aversion parameters to assess how preferred strategies vary under different societal preferences for equity.
Results: This study will quantify how the costs and health benefits of CRC screening are distributed across SES groups under current NBCSP practice and scenarios with improved participation and/or follow-up. It will identify the main drivers of inequalities in CRC screening outcomes and highlight opportunities to improve equity through health policy investment. Equity-weighted analysis will assess whether preferred strategies vary with societal preferences for equity. Model analyses are currently underway, with results available before conference presentation.
Conclusions: By identifying the drivers of inequalities and assessing the equity implications of alternative screening strategies, this study will provide evidence to support more equitable implementation of the NBCSP and inform future policy decisions.