INTRODUCTION:
Many effective health system interventions fail to scale. Our research collaboration plans to evaluate the scale-up of PACK (Practical Approach to Care Kit), a health systems strengthening (HSS) intervention implemented in six low- and middle-income countries (LMICs). To inform our evaluation methodology, we conducted a scoping review to identify criteria, measures, and frameworks used to evaluate scale-up of HSS interventions.

METHODS:
We followed the Preferred Reporting Items for Systematic Review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and Arksey and O’Malley framework. We systematically searched Pubmed, Cinahl, Cochrane and Google scholar, identifying additional sources via snowball methodology. Eligibility criteria included primary studies and reports from stakeholder organisations (e.g. WHO) focusing on evaluation of primary care HSS scale-up. The criteria included low- and high-income countries and did not restrict by disease. Covidence, a web-based tool, was used to screen by pairs of reviewers. Discrepancies were resolved by discussion. A customized extraction tool was developed to collate data. Data extraction and analysis are ongoing to derive a consolidated list of methodologies. A stakeholder meeting is planned to contribute to appraisal and interpretation of findings.

RESULTS:
The search identified 1129 articles for screening. 77 progressed to full-text review; ultimately, 16 satisfied eligibility criteria. All but one had an LMIC focus. Six were disease-agnostic, nine covered a clinical topic and one focussed on scale-up of a health system management strategy. A range of approaches were identified, including conceptual frameworks, scale-up models and pragmatic checklists.

CONCLUSIONS:
Our scoping review is ongoing but the evidence landscape for evaluating scale-up of HSS initiatives appears heterogeneous. A critical appraisal of what works and how will inform future HSS evaluation methodology and contribute to the scale-up literature.