Building process improvement capacity in epidemiologic research operations: the Nurses’ Health Studies experience

With declining infrastructure funding for large-scale epidemiologic cohort studies, continuous process improvement is essential to sustain research quality and impact. The authors recently undertook a Lean Six Sigma (LSS) training initiative with operational staff of the Nurses' Health Studies, among the longest-running and most productive cohort studies, to modernize operations and build internal capacity for process improvement. Twenty staff members across operational domains completed a structured LSS curriculum and three improvement projects: (1) reducing median turnaround time for medical record retrieval by 90%, (2) decreasing the proportion undeliverable questionnaires by 31%, and (3) cutting biweekly freezer maintenance time by 43 person-minutes per cycle, yielding an estimated 6.5 person-weeks annually. Staff reported substantial increases in understanding and confidence in applying process improvement methods. Fourteen trainees completed all requirements for LSS green-belt certification. Though some participants questioned the need to learn a specialized framework, most valued the collaborative, data-driven approach. This experience demonstrates that LSS can be successfully adapted to non-clinical trial epidemiologic research, improving efficiency and data quality. By improving data completeness and integrity, operational improvements reduced sources of bias in downstream analyses. The results support broader adoption of structured continuous improvement efforts to enhance the sustainability of epidemiologic research platforms.