Quantification of K18:
Samples were stored at -80°C before analysis. K18 was quantified in samples from healthy volunteers and patients in the ALISTER study, with these samples stored for a maximum of just over 2 years (113 weeks) (median [IQR]: 48.4 [28.7-77.8] weeks) prior to analysis. K18 was quantified in serum samples from the SAEFRIF trial, these samples were stored for a maximum of 1 year (median [IQR]: 19.1 [11.1-26.2] weeks). Total K18 was quantified using the Peviva M65 classic ELISA (Bioaxxes, Tewkesbury, UK), according to the manufacturer’s instructions. Samples were measured in duplicate. CV values for the dataset were (median [IQR]: 2.85%, [1.33-4.97%]). Reproducibility was determined using the provided plate controls.