Core outcome sets and benchmarking complications: Defining best practices for standardized outcome reporting in liver transplantation

The comparison of outcomes in liver transplantation (LT) is hampered by using clinically nonrelevant surrogate endpoints and considerable variability in reported relevant posttransplant outcomes. Such variability stems from nonstandard outcome measures across studies, variable definitions of the same complication, and different timing of reporting. The Clavien-Dindo classification was established to improve the rigor of outcome reporting but is nonspecific to an intervention, and there are unsolved dilemmas specifically related to LT. Core outcome sets (COSs) have been used in other specialties to standardize outcomes research, but have not been defined for LT. Thus, we use the 5 major benchmarking studies published to date to define a 10-measure COS for LT using previously validated metrics. We further provide standard definitions for each of the 10 measures that may be used in international research on the topic. These definitions also include standard time points for recording to facilitate between-study comparisons and future meta-analysis. These 10 outcomes are paired with 3 validated, procedure-independent metrics, including the Clavien-Dindo Classification and the Comprehensive Complications Index. The Clavien scale and Comprehensive Complications Index are specifically reviewed to enhance their utility in LT, and their use, along with the COS, is explored. We encourage future studies to employ this COS along with the Clavien-Dindo grading system and Comprehensive Complications Index to improve the reproducibility and generalizability of research concerning LT.