Impact of a peer-facilitated training intervention on nurses’ knowledge of preanalytical laboratory errors: a multicenter before-and-after study

Background: Errors in the preanalytical phases explain up to 70% of laboratory errors, leading to clinical delays and safety risks. Nurses play a central role in blood sample collection and handling; however, the training is frequently inconsistent and not standardized. The aim of this study was to assess baseline preanalytical knowledge of nurses, evaluate the impact of a peer-facilitated training intervention, and compare outcomes between a central and peripheral hospital. Methods: A multicenter interventional before-and-after study was conducted among nurses from the internal medicine services of two hospitals. A questionnaire on common preanalytical errors was administered before a training workshop and repeated 1 month later. Participation was voluntary. Preintervention and postintervention correct response rates were compared overall and by knowledge domains using SPSS v30 using descriptive and comparative methods. Results: The sample included 122 nurses (80 central, 42 peripheral), predominantly female (>75%). Training adherence was higher in the peripheral hospital (64.3%) than in the central hospital (36.3%). Accuracy improved in both centers (60.9%–70.7% in the central hospital; 68.3%–86.8% in the peripheral hospital), especially in domains related to the frequency of preanalytical errors and packaging. Untrained groups showed an overall reduction in performance at follow-up, although not statistically significant. Discussion/Conclusion: Peer-facilitated training improved nurses' preanalytical knowledge and may represent a practical, low-cost strategy to enhance preanalytical quality and patient safety. Further research is warranted to determine the sustainability of these gains over time.