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Effectiveness of Toyota Process Redesign in Reducing Thyroid Gland Fine-Needle Aspiration Error

Stephen S. Raab MD, Dana Marie Grzybicki MD, PhD, Daniel Sudilovsky MD, Ronald Balassanian MD, Janine E. Janosky PhD, Colleen M. Vrbin
DOI: http://dx.doi.org/10.1309/NJQ1L7KA10UKV93Q 585-592 First published online: 1 October 2006


Our objective was to determine whether the Toyota Production System process redesign resulted in diagnostic error reduction for patients who underwent cytologic evaluation of thyroid nodules. In this longitudinal, nonconcurrent cohort study, we compared the diagnostic error frequency of a thyroid aspiration service before and after implementation of error reduction initiatives consisting of adoption of a standardized diagnostic terminology scheme and an immediate interpretation service. A total of 2,424 patients underwent aspiration. Following terminology standardization, the false-negative rate decreased from 41.8% to 19.1% (P = .006), the specimen nondiagnostic rate increased from 5.8% to 19.8% (P < .001), and the sensitivity increased from 70.2% to 90.6% (P < .001). Cases with an immediate interpretation had a lower noninterpretable specimen rate than those without immediate interpretation (P < .001). Toyota process change led to significantly fewer diagnostic errors for patients who underwent thyroid fine-needle aspiration.

Key Words:
  • Patient safety
  • Error reduction
  • Thyroid gland
  • Fine-needle aspiration
  • Immediate interpretation