Figure 2. Causal Hypothesis Diagram.

The direct effect is defined as pathway C, and the indirect effect is defined as pathways A × B. Rectangles represent observed variables; ovals represent latent variables. Linear equations are built by using arrows between the variables; 90-day functional outcome was included as an ordinal variable following the full categorical scale (ie, modified Rankin Scale, which ranges from 0 to 6, with 0 indicating perfect health without symptoms and 6 indicating death).

^aThis model is repeated 2 times; a different model is created for each latent variable as a different mediator (ie, neuroimaging frailty and composite frailty).