Background/purpose: People with different age distributions and extrication times might have distinct injury characteristics and outcomes in earthquakes. Methods: A retrospective study was conducted to analyze the casualties in the 2016 Taiwan earthquake using data from the incident registry system and the field disaster operation system. The study subjects were assigned to 4 groups by age: preschool (<5 years), school (5–17 years), adult (18–64 years), and elderly (>64 years). Classification and regression tree analysis and receiver-operating characteristic curves were utilized to examine several factors, including extrication time, age group, floor height, and structural damage, for earthquake-related mortality. A two-sided p value less than 0.05 was considered statistically significant. Results: A total of 238 enrollees were assigned to the preschool (n = 18, 7.6%), school (n = 45, 18.9%), adult (n = 169, 71.0%), or elderly (n = 6, 2.5%) groups. Among the parameters, the extrication time exhibited the strongest association with mortality. Regarding the association between the extrication time and mortality hazard in multivariate models, we found significant odds ratios (ORs) at the extrication time cutoffs of 12, 24 and 72 h (OR = 42.61, 95% confidence interval [CI]: 13.92–130.37; OR = 37.58, 95% CI: 14.77–95.60; OR = 95.16, 95% CI: 23.02–393.48, respectively, all p < 0.001). The optimal extrication time cutoff for mortality was 12 h in the preschool group and 24 h in the school and adult groups. Conclusion: Extrication time is strongly associated with earthquake-related mortality. These findings may facilitate strategic approaches for patients entrapped in damaged buildings and can contribute to future training for field search and rescues after earthquakes.
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