Strengths and limitations
The strengths of this systematic review include its comprehensive search strategy and design ensuring the study selection, data extraction, and methodological and reporting quality assessment were conducted independently by two authors. It is limited however by restricting the search strategy to two databases. We contacted all registered study authors and found no additional publications. There are no established criteria to assess the usability of completed outcome sets. No decisions about the usability, feasibility, and applicability can therefore be made.