The last decade has seen growing interest in scaling up of innovations to strengthen healthcare systems. However, the lack of appropriate methods for determining their potential for scale-up is an unfortunate global handicap. Thus, the authors aimed to review tools proposed for assessing the scalability of innovations in health.

The authors conducted a systematic review following the COSMIN methodology. They included any empirical research which aimed to investigate the creation, validation or interpretability of a scalability assessment tool in health. They searched Embase, MEDLINE, CINAHL, Web of Science, PsycINFO, Cochrane Library and ERIC from their inception to 20 March 2019 and also searched relevant websites, screened the reference lists of relevant reports and consulted experts in the field. 

The authors identified 31 reports describing 21 tools. Types of tools included criteria (47.6%), scales (33.3%) and checklists (19.0%). Most tools were published from 2010 onwards (90.5%), in open-access sources (85.7%) and funded by governmental or nongovernmental organizations (76.2%). Most tools provided limited information on content validity (85.7%), and none reported on other measurement properties. The methodological quality of tools was deemed inadequate (61.9%) or doubtful (38.1%).

The authors concluded that existing tools are as yet of limited utility for assessing scalability in health. More work needs to be done to establish key psychometric properties of these tools.