Lean thinking in hospitals: is there a cure for the absence of evidence? A systematic review of reviews

Objective: Lean interventions aim to improve quality of healthcare by reducing waste and facilitate flow in work processes. There is conflicting evidence on the outcomes of lean thinking, with quantitative and qualitative studies often contradicting each other. We suggest that reviewing the literature within the approach of a new contextual framework can deepen our understanding of lean as a quality-improvement method. This article theorises the concept of context by establishing a two-dimensional conceptual framework acknowledging lean as complex social interventions, deployed in different organisational dimensions and domains. The specific aim of the study was to identify factors facilitating intended outcomes from lean interventions, and to understand when and how different facilitators contribute. Design: A two-dimensional conceptual framework was developed by combining Shortell's Dimensions of capability with Walshes' Domains of an intervention. We then conducted a systematic review of lean review articles concerning hospitals, published in the period 2000-2012. The identified lean facilitators were categorised according to the intervention domains and dimensions of capability provided by the framework. Results: We provide a framework emphasising context by relating facilitators to domains and dimensions of capability. 23 factors enabling a successful lean intervention in hospitals were identified in the systematic review, where management and a supportive culture, training, accurate data, physicians and team involvement were most frequent. Conclusions: In the absence of evidence, the two-dimensional framework, incorporating the context, may prove useful for future research on variation in outcomes from lean interventions. Findings from the review suggest that characteristics and local application of lean, in addition to strategic and cultural capability, should be given further attention in healthcare quality improvement.