Medical adverse event (MAE) reporting and management are essential for patient safety campaigns. An epidemiological assessment of MAE trends is crucial for understanding the effectiveness of patient safety improvement efforts. This study analyzed the trends of inpatient MAEs, focusing on MAE incidence and harm severity. Longitudinal secondary data (over 2014-2020) on MAEs reported by 18 hospitals were retrieved from the Taiwan Patient-safety Reporting system. The numbers and incidence rates (per 1000 inpatient days) of reported MAEs were calculated. The harm severity levels of six major MAE categories were analyzed. Trend and generalized estimating equation analyses were conducted to investigate changes in MAE patterns. Trend analyses revealed significant decreasing trends in the number (4763-3107 per year; Jonckheere-Terpstra test = -1.952, P = 0.05) and incidence rates (0.92-0.62 per 1000 inpatient days; β = -0.5017, P = 0.00) of harmful MAEs over 7-year study period. Among the most frequently reported MAEs, tube-related events exhibited the most significant decreasing trend (28%-23.8%; Jonckheere-Terpstra test = -2.854, P = 0.00). The reported numbers, incidence rates, and severity of falls and tube-related events dropped significantly. By analyzing representative longitudinal MAE data, this study demonstrated the effectiveness of nationwide patient safety improvement campaigns in Taiwan. Our data reveal significant reductions in the reported numbers, incidence rates, and severity of several major MAEs. Specifically, our data indicate significant reductions in the incidence and severity of tube-related events, which can be beneficial for patient safety improvement efforts.