Rate of Spleen Length Progression is a Marker of Outcome in Patients with Primary Sclerosing Cholangitis

Patients with primary sclerosing cholangitis (PSC) tend to develop progressive liver fibrosis and end-stage liver disease within 10-20 years. 1 The International PSC Study Group declared research on surrogate endpoints a high-priority task not least for ongoing clinical trials on novel treatment options. 2 The spleen in patients with PSC often enlarges even before cirrhosis develops. Transient elastography (TE) has been investigated as a dynamic and prognostic marker in PSC. 3,4 However, TE is not generally accessible, measures only a small part of the right liver, and is prone to errors in obese patients, and liver stiffness is related to postprandial status, liver inflammation, and biliary obstruction. 5 We have recently demonstrated that single-point spleen length (SL) measurement has a prognostic performance similar to liver stiffness measured by TE. 3,4,6 SL measurement is a fast, simple, and ubiquitously available method. However, absolute spleen size depends on body height and sex, 7 and single-point measurement of SL cannot be used to assess the effects of therapeutic interventions. To overcome these issues, we assessed the intra-individual development of spleen size over time (delta spleen length: dSL = SL 2 - SL 1) to evaluate its role as a novel surrogate marker, which accounts for the dynamic nature of PSC progression.