Purpose: To describe the long-term quantitative change in the number of submissions of patient safety reports after the introduction of a patient safety reporting system, focusing on incident severity and type. Patients and Methods: This study was performed at a tertiary care hospital in Japan. Patient safety reports from 2006 to 2020 were retrospectively reviewed. Incident severity was classified from level 0 (near miss) to level 5 (fatality). The incident types included those related to medication, patient care, drains and catheters, procedures and interventions, examinations, medical devices, and blood transfusions. The study period was divided into 1. 2004–2007; 2. 2008–2014; and 3. 2015–2020 based on the implementation of hospital patient safety strategies. The number of reports per hospital worker was compared among the study periods and the incident levels and types. Results: We analyzed 96,332 reports extracted from the patient safety reporting system of the hospital. The total number of reports per hospital worker has increased over time. The numbers of levels 0 and 1 incidents increased throughout the study period. In addition, levels 3a and 3b incidents increased between periods 2 and 3. All incident types, except for procedure and intervention-related incidents, increased between periods 1 and 2 and between periods 1 and 3. The number of procedure and intervention-related incidents increased between periods 2 and 3, although it did not between periods 1 and 2. Conclusion: We found increases in the number of patient safety reports according to the incident severity and type. This suggests two contextual changes occurring during the cultural maturity process, which reflected the development of organizational patient safety culture in our institution. The first was the establishment of a reporting attitude in the institution. The second was to overcome barriers to patient safety.
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