Emergency Department Wait Times as a System-Level Challenge: Drivers, Process Inefficiencies, and Lean Six Sigma Solutions

Emergency departments (EDs) are often the first point of care for patients in urgent need, yet long waiting time remains a persistent and frustrating problem across many healthcare systems. Patients frequently wait hours before being seen, not always because hospitals lack resources, but because care processes are complex, fragmented, and difficult to manage in real time. These delays worsen clinical outcomes, reduce patient satisfaction, and place serious pressure on both patients and healthcare staff. This study explores key factors driving ED waiting times and evaluates the role of process improvement approaches, particularly Lean and Lean Six Sigma (LSS). Using a critical review with structured narrative synthesis, relevant studies published between 2010 and 2023 were identified across Google Scholar, PubMed, MEDLINE, Embase and PubMed Central (PMC). The findings show that while rising and unpredictable patient demand is an important driver of delays; inefficiencies in how care is organised and delivered such as bottlenecks in triage, delays in diagnostics and admissions, organisational dynamics and poor coordination across hospital units, often play an even bigger role. Process improvement approaches such as LSS are consistently associated with better patient flow and reduced waiting times, but the evidence also shows that their success depends heavily on how well they are implemented and adapted to local conditions. This study concludes that improving waiting times is not just a technical or operational issue. Organisational culture, staff workload, communication, and equity-related factors all shape how patients move through the system. In some cases, efforts to improve efficiency such as strict time targets, can create unintended consequences, including staff burnout or reduced quality of patient interaction. As such, meaningful improvement requires a system-wide approach that combines process redesign, better use of data, stronger coordination, and attention to both staff and patient experience.