Abstract
Lean Six Sigma (LSS) is a process improvement methodology that combines Lean's focus on eliminating non-value-adding activities with Six Sigma's data-driven approach to reduce defects and enhance efficiency and quality. Globally, the healthcare sector faces challenges, such as resource constraints, rising patient demands, and infrastructural limitations, with these challenges particularly pronounced in developing countries, like India, making it a promising tool for optimizing processes and improving patient outcomes. Despite its potential, the adoption of LSS in Indian healthcare is limited, and critical success factors (CSFs) such as leadership, communication, training, and organizational culture remain underexplored. This study investigated global research trends, thematic interconnections, and identified geographical gaps in LSS implementation, particularly revealing the underrepresentation of developing countries like India in the literature. A bibliometric analysis was conducted using data from the Scopus, PubMed, and Web of Science databases, covering peer-reviewed English-language articles published between January 2012 and April 2024, followed by a qualitative systematic review of the identified studies (n = 8). A targeted search strategy employed keywords, such as "Lean Six Sigma," "Critical Success Factors," "Service Quality," AND, OR "Healthcare," combined with Boolean operators (AND, OR). The inclusion criteria required articles to address service quality, focusing on CSFs involved in the successful implementation of LSS in healthcare settings. The exclusion criteria excluded non-peer-reviewed studies, conference abstracts, articles not in the English language, and non-healthcare studies. From the 262 retrieved articles, metadata, including titles, authors, abstracts, and keywords, were extracted, cleaned for duplicates, and analyzed using VOSviewer, version 1.6.20 (Leiden University) to map keyword co-occurrences and co-authorship networks. The analysis identified a robust global LSS research ecosystem, with core terms such as "Service Quality", "Lean", and "Six Sigma, forming a dense central cluster, red coloured, linked to healthcare themes such as "CSFs" (68 co-occurrences) and "patient safety" (44 co-occurrences). The analysis revealed significant geographical disparities, with developing countries underrepresented; for instance, India contributed only 1 out of 262 (0.38%) publications, highlighting a critical research gap in emerging economies. Organizational Culture (39 co-occurrences) and Training (35 co-occurrences) were universal CSFs in healthcare studies, followed by Communication (28 co-occurrences) as per the bibliometric keyword analysis. Whereas a qualitative systematic review revealed Leadership and management as the most universal factors (8/8 studies). Communication was prominent too (6/8), followed by training and expertise, and organizational readiness (5/8 and 3/8 each), whereas technology integration and employee retention, and culture were least cited (1/8). Western nations dominate the research output, highlighting geographical disparities. The neglect of technology integration, employee retention, and data-driven decision making as CSFs underscores barriers in resource-constrained environments. Future research should prioritize India-specific studies and integrate cost-effective solutions and longitudinal assessments to enhance LSS adoption and improve health care delivery.