Background: Lean is a quality improvement management system from the Toyota manufacturing industry. Since the early 2000's, Lean has been used as an intervention for healthcare improvement. Lean is intended to reduce costs and improve customer value through continuous improvement. Despite its extensive use, the contextual factors and mechanisms that influence the sustainability of Lean in healthcare have not been well studied. Realist synthesis is one approach to "unpack" the causal explanations of how and why Lean is sustained or not in healthcare. We conducted a realist synthesis using the context (C) + mechanim (M) = outcome (O) heuristic, to further develop and refine an initial program theory with seven CMO hypotheses, on the sustainability of Lean efforts across pediatric healthcare.
Methods: Our search strategy was multi-pronged, iterative, and purposeful in nature, consisting of database, gray literature, and contact with three healthcare organizations known for Lean implementation. We included primary research studies, published and unpublished case studies or reports, if they included Lean implementation with a pediatric focus and sustainability outcome. We used the Normalization Process Theory and the National Health Services Sustainability Model, an operational definition for Lean and a comprehensive definition for sustainability as guidance for data extraction and analysis. Our initial program theory with was refined using a blend of abductive and retroductive analytical processes.
Results: We identified six published primary research studies, two published quality improvement case studies, and three unpublished quality improvement case reports. Five CMO hypotheses from our initial program theory were substantially supported after synthesis, "sense-making and value congruency," "staff engagement and empowerment," and the "ripple effect" or causal pathway between Lean implementation outcomes that served as facilitating or hindering contexts for sustainability. Overall, there was variation with the conceptualization and measurement of sustainability.
Conclusions: This study is the first to examine Lean sustainability in pediatric healthcare using realist methods. Future research should examine whether the predictors of implementation are the same or different to sustainability and evaluate the underlying mechanisms that influence the sustainability of Lean. There is also a need for research to develop and test conceptual models and frameworks on sustainability.
Systematic review registration: PROSPERO-CRD42015032252 .
Keywords: Complex intervention; Implementation science; Lean; Pediatric healthcare; Quality improvement; Realist review; Sustainability.