Modelling cost-effective strategies for minimising socioeconomic inequalities in colorectal cancer screening outcomes in England

Colorectal cancer (CRC) incidence and mortality is higher in socioeconomically deprived groups for a variety of reasons, but is exacerbated by poorer screening uptake. However, many strategies for improving screening participation exist. This analysis aimed to model the impact of screening on CRC inequalities in England and then compare different strategies for increasing participation, to determine the most cost-effective methods for reducing screening-induced inequalities. An existing health economic model, Microsimulation Model in Cancer of the Bowel was adapted. Screening-eligible individuals were simulated to investigate the impact of screening on CRC inequalities. Following this, four strategies for promoting screening participation were compared: 1) annual re-invitation of screening non-participants; 2) a national media advertising campaign; 3) text message reminders for non-participants; 4) health promotion in deprived populations. Cost-effectiveness, CRC outcomes, resource impacts and effects on CRC inequalities were assessed. Inequalities analysis was based on age-standardised CRC mortality by socioeconomic group. Screening was found to be highly cost-effective but CRC inequalities increased as screening effectiveness improved. Annual re-invitation of non-participants was most cost-effective for promoting particiption (incremental cost-effectiveness ratio = £4404 per quality-adjusted life-year), reducing CRC mortality (11,129 deaths averted), and reducing screening-induced inequality (slope of inequalities reduced from 20.80 to 19.38), although it required 42% more screening kits to be sent out. Other strategies were cost-effective compared with screening alone, and improved CRC outcomes, but had varying impacts on inequalities. Whilst bowel cancer screening increases socioeconomic inequalities in CRC mortality, effective and cost-effective strategies are available for mitigating screening-induced inequalities.