Fig. 1

Treatment effect estimates (chemoimmunotherapy versus chemotherapy) with continuous BMI by the method of Multivariate Fractional Polynomial Interaction with Cox proportional-hazard regression models stratified by trial for overall survival (a) and progression-free survival (b). The shaded area is the 95% CIs of the treatment effect estimated as hazard ratios (HRs) (black solid line). Vertical dotted lines mark the 5^th and 95^th percentile of BMI distribution of the pooled analysis cohort, at 19.8 kg/m² and 34.7 kg/m² respectively