Causal Relationship between Treatment and Mayo Subscores
The endoscopic appearance of the colon, as determined by sigmoidoscopy, is considered to be a causal effect for the other three Mayo score items. Therefore, the related fragment of the overall mediation model could be “extracted” for a more detailed examination as it was implied and shown as part of the respecified models. Therefore, it could be assumed that tofacitinib treatment causes changes in sigmoidoscopy, which in turn causes changes in PGA/rectal bleeding/stool frequency (i.e., indirect effects of tofacitinib treatment on PGA/rectal bleeding/stool frequency via sigmoidoscopy), and tofacitinib treatment also causes direct changes in PGA/rectal bleeding/stool frequency (shown in Fig. 