ABSTRACT
Abstract The mucopolysaccharidoses (MPS) are a relatively uncommon group of inherited metabolic disorders, with significant negative implications for life span and aspects of quality of life. Their rarity means that producing evidence to guide best practice has often entailed assimilating findings from multiple studies. Core outcome sets (COS) are being increasingly used across medicine as a potential solution to the problems arising from heterogeneous reporting of outcomes in effectiveness studies. A COS is a recommended minimum set of outcomes that should be measured for a given condition in an effectiveness study, with the ultimate aim of increasing the value of clinical information by enabling meaningful comparison and combination of data from various sources. A systematic review identified 41 outcomes measured in published studies and ongoing and completed clinical trials, with individual outcomes being measured using a variety of measurement instruments/tools. This work represents the important initial steps in the development of COS for head, neck, and respiratory disorders in MPS type II, raising awareness of the extent of heterogeneity in outcome reporting and determining the scope of outcomes and corresponding instruments currently used. The next step will be to use the generated "longlist" of outcomes to develop an electronic Delphi prioritization exercise with the intention of reaching a consensus regarding the most important outcomes to measure in effectiveness studies for head, neck, and respiratory disease in MPS type II.