P101 Mediation analysis investigating potential determinants of the survival gap between the sexes in cystic fibrosis; a complex picture

Objectives: Current median survival in the UK 2021 is 51.4 years for females, and 55.3 males. We used mediation analysis to further understanding of causal pathways leading this disparity. Methods: CF Registry data up 2020 investigate extent which difference life expectancy between males females explained by trajectories markers disease progression over course. considered lung health (represented FEV1%, pathogens other variables), cystic fibrosis related diabetes (CFRD), BMI z-score as potential mediators. A was used, accommodates longitudinal variables baseline time-dependent dependent confounders. The mediated proportion (MP) a given mediator at age defined percentage sexes probability that would change if trajectory shifted be similar Results: included 6,341 5,771 (survival 30, 0.68 0.76 males). From preliminary analyses MPat 30was 62.9% (95% CI 34.3-223.5%) health, i. e. female closer For CFRD MP 30 11.0% (3.6% - 38.1%). older ages smaller but larger CFRD, suggesting mediating role ages. negative (-28.3%, 95% -(103.4% 12.4%)) meaning had same then their expected 28.3% worse. Conclusions: Several different factors were found mediate effect sex on CF. most important factor health. Further work will mediators subcomponents