Adams Annette L, Schmidt Terri A, Newgard Craig D, Federiuk Carol S, Christie Michael, Scorvo Sean, DeFreest Melissa
Department of Public Health and Preventive Medicine, Oregon Health & Science University, Portland, OR 97239-3089, USA.
Wilderness Environ Med. 2007 Summer;18(2):95-101. doi: 10.1580/06-WEME-OR-035R1.1.
The purpose of this study was to derive and validate a rule for duration of search (ie, search time) that maximizes survivors and after which a search and rescue (SAR) mission may be considered for termination.
This was a retrospective cohort study of all SAR missions initiated in Oregon over a 7-year period, which were documented in a population-based administrative database. The following types of search missions were excluded from analysis: redundant reports of a single search; lost helicopters and airplanes; support of organized events; law-enforcement searches; searches for persons actively avoiding rescue; body recovery missions; and cases without outcome information. The cohort was divided into a derivation cohort (searches from 1997-2000) and a validation cohort (2001-2003). The primary outcome was survival. Variables considered in the model included age, gender, minimum and maximum daily temperatures, precipitation, search time, and whether the search involved an air or water incident. Missing data were handled using multiple imputation. Classification and regression tree (CART) methods were used to derive the model.
The derivation cohort included 1040 searches involving 1509 victims, 70 (4.6%) of whom died. The validation cohort included 1262 searches involving 1778 victims; 115 (6.5%) died. Search time was the only variable retained in the final model, with a cut-point of 51 hours. The derivation model was 98.9% sensitive; the same model run using the validation cohort was 99.3% sensitive.
This time-based model may aid search managers in the decision about starting a search or changing search tactics for missing persons.
本研究旨在推导并验证一个搜寻持续时间（即搜索时间）规则，该规则能使幸存者数量最大化，且在此之后可考虑终止搜索与救援（SAR）任务。
这是一项对俄勒冈州7年间发起的所有SAR任务进行的回顾性队列研究，这些任务记录在一个基于人群的行政数据库中。分析中排除了以下类型的搜索任务：单次搜索的重复报告；丢失的直升机和飞机；有组织活动的支持；执法搜索；对积极躲避救援人员的搜索；尸体回收任务；以及无结果信息的案例。队列被分为推导队列（1997 - 2000年的搜索）和验证队列（2001 - 2003年）。主要结局是生存情况。模型中考虑的变量包括年龄、性别、每日最低和最高温度、降水量、搜索时间，以及搜索是否涉及空中或水上事件。缺失数据采用多重填补法处理。使用分类与回归树（CART）方法推导模型。
推导队列包括1040次搜索，涉及1509名受害者，其中70人（4.6%）死亡。验证队列包括1262次搜索，涉及1778名受害者；115人（6.5%）死亡。搜索时间是最终模型中保留的唯一变量，切点为51小时。推导模型的敏感性为98.9%；使用验证队列运行的同一模型敏感性为99.3%。
这个基于时间的模型可能有助于搜索管理人员决定是否展开搜索或改变对失踪人员的搜索策略。
