Predictors of Frequent Emergency Room Visits in Patients with History of Illicit Drug Use.

a Denotes statistical significance. p b Defined as one or more housing status changes within a 1 year follow-up period from index ambulatory visit.c Reference group for these categories are patients without these health characteristics.d Health service utilization data collected over a 1 year follow-up time period from index ambulatory visit. Reference group was 0–2 visits per year.Predictors of Frequent Emergency Room Visits in Patients with History of Illicit Drug Use.a 表示统计学显著性。b 定义为自索引门诊就诊（index ambulatory visit）起1年随访期内出现1次及以上住房状况变动。c 上述分类的参照组为无此类健康特征的患者。d 卫生服务利用（health service utilization）数据采集自索引门诊就诊后的1年随访期，参照组为每年就诊0~2次的患者。有违禁药物使用史患者的频繁急诊就诊预测因素。