Lammers R L, Roth B A, Utecht T
Department of Emergency Medicine, Michigan State University/Kalamazoo Center for Medical Studies, USA.
Ann Emerg Med. 1995 Nov;26(5):579-89. doi: 10.1016/s0196-0644(95)70008-0.
To compare rates of undertriage and overtriage of six ambulance dispatch protocols for the presenting complaint of nontraumatic abdominal pain, and to identify the optimal protocol.
Retrospective prehospital and emergency department chart review to classify patients' conditions as "emergency" or "nonemergency." Utility analysis was used to identify the preferred protocol and monetary cost-effectiveness analysis to identify the least expensive protocol.
County emergency medical services (EMS) system with five receiving hospitals serving a mainly urban population of approximately 350,000.
Records of 902 patients who called 911 for nontraumatic abdominal pain were reviewed; patients not transported were excluded. Twenty-seven county EMS medical directors completed questionnaires.
Six ambulance dispatch protocols for nontraumatic abdominal pain were developed: indiscriminate-dispatch, four selective protocols, and no-dispatch. A dichotomous classification system was derived prospectively from the prehospital and medical records of patients who had activated the EMS system before the study period to define "emergency" and "nonemergency" conditions associated with nontraumatic abdominal pain. Emergency criteria identified patients with conditions requiring medical treatment within 1 hour. Reviewers determined, for each patient, whether an ambulance would have been dispatched by each of the protocols. Undertriage and overtriage rates were calculated for each protocol. County EMS medical directors assigned utility values to four potential outcomes of ambulance dispatch by the direct scaling method. The outcomes comprised correct and incorrect decisions to dispatch ambulances to patients with and without emergencies. The protocols were compared by decision analysis. A cost analysis was also performed, using an estimated marginal cost per transport of $302. Sensitivity analysis demonstrated the effect of varying the cost of an undertriage error and the cost per response. Of the 788 patients included in the study, 7.8% had conditions defined as emergencies. The four selective ambulance dispatch protocols had overtriage rates ranging from 10% to 51% and undertriage rates of 4% to 7%. None of the protocols was proven superior on the basis of the medical directors' assignment of utility values. The marginal cost of dispatching advanced life support ambulances to all patients with this complaint was $3,838 per emergency.
The majority of patients with nontraumatic abdominal pain who requested ambulance transport during the study period did not have conditions that were classified as emergencies. In the study model, if an undertriage error costs more than $3,674, indiscriminate ambulance dispatch is the least expensive protocol, and if an undertriage error costs less than $3,674, no ambulance dispatch is the least expensive strategy.
比较六种针对非创伤性腹痛主诉的救护车调度协议的分诊不足和分诊过度发生率，并确定最佳协议。
回顾性分析院前和急诊科病历，将患者病情分类为“紧急”或“非紧急”。采用效用分析确定首选协议，采用货币成本效益分析确定成本最低的协议。
县紧急医疗服务（EMS）系统，有五家接收医院，服务于主要为城市人口的约35万居民。
回顾了902例因非创伤性腹痛拨打911的患者记录；未转运的患者被排除。27名县EMS医疗主任完成了问卷调查。
制定了六种针对非创伤性腹痛的救护车调度协议：无差别调度、四种选择性协议和不调度。前瞻性地从研究期间之前激活EMS系统的患者的院前和病历中得出二分分类系统，以定义与非创伤性腹痛相关的“紧急”和“非紧急”情况。紧急标准确定了需要在1小时内接受治疗的患者。评审员为每位患者确定每种协议是否会调度救护车。计算每种协议的分诊不足和分诊过度发生率。县EMS医疗主任通过直接标度法为救护车调度的四种潜在结果赋予效用值。结果包括向有紧急情况和无紧急情况的患者派遣救护车的正确和错误决定。通过决策分析比较这些协议。还进行了成本分析，估计每次转运的边际成本为302美元。敏感性分析显示了改变分诊错误成本和每次响应成本的影响。在纳入研究的788例患者中，7.8%的患者病情被定义为紧急情况。四种选择性救护车调度协议的分诊过度发生率在10%至51%之间，分诊不足发生率在4%至7%之间。根据医疗主任赋予的效用值，没有一种协议被证明更优越。向所有有此主诉的患者派遣高级生命支持救护车的边际成本为每次紧急情况3838美元。
在研究期间请求救护车转运的大多数非创伤性腹痛患者的病情未被分类为紧急情况。在研究模型中，如果分诊错误成本超过3674美元，无差别救护车调度是成本最低的协议；如果分诊错误成本低于3674美元，不进行救护车调度是成本最低的策略。
