中文摘要：

目的了解四川省西昌市吸毒人群从首次口吸毒到首次静脉注射吸毒的发生情况。方法于2004-05／07从社区中招募吸毒人群，调查其社会人口学、首次吸毒前吸烟、饮酒情况、首次吸毒的时间和方式及种类、首次静脉注射吸毒情况。结果在调查的451名吸毒人员中，首次使用的毒品均为海洛因，其中，首次为口吸和静脉注射的分别为80．7％（364／451）和19．3％（87／451）。从首次口吸到首次静脉注射的发生率为21．82／100人年（95％ CI为19．60～24．05），多因素Cox比例风险模型分析结果显示，初中以下文化（HR=1．38；95％ CI为1．12～1．70）和15岁以前开始吸烟（HR=1．41；95％ CI为1．15～1．73）与首次口吸到首次静脉注射发生的关系有统计学意义。结论首次口吸到静脉注射毒品的时间与文化程度有关，这一转变的发生率也与吸毒人群吸烟早迟有关。但需进一步了解吸毒人群首次静脉注射吸毒的发生情况及其影响因素。

英文摘要：

Objective To understand effect factors of time from initiation of drug use to adoption of injection among drug users in Xichang city of Sichuan province. Methods During May to July in 2004, a community-based survey was carried out to collect relative information among drug users including their demographic characteristics, smoking and drinking situations before initial drug use, time and routes of initial drug use, types of initial drug used and situations of initial drug injection. Results A total of 451 drug users were interviewed. The initial drug used was heroin. Of all subjects, 80.7% （364/451） and 19.3% （87/451） reported the initial route of sniffing and injecting heroin, respectively. The incidence of change from initial drug use to drug injection was 21.82 per 100 person-year （95% CI 19.60 - 24.05）. The analysis results of multivariate Cox proportional hazard regression model indicated that culture degree of junior high school or less （HR = 1.48; 95% CI 1.23 - 1.79） and smoking before 15 years old （HR = 1.52; 95% CI 1.23 - 1.88） were independently associated with time from initiation of drug use to drug injection. Conclusions Culture degree and smoking before 15 years old are effect factors of time from initiation of drug use to adoption of injection among drug users. But it is necessary to clarify effect factors further in order to provide scientific guidelines for prevention of drug use through health education and behavioral intervention.