López-Zetina J, Ford W, Weber M, Barna S, Woerhle T, Kerndt P, Monterroso E
Los Angeles County, Department of Health Services, HIV Epidemiology Program, Los Angeles, California, USA.
Sex Transm Infect. 2000 Dec;76(6):462-9. doi: 10.1136/sti.76.6.462.
To describe HIV prevalence and the association between syphilis incidence and sexual and drug injection risk behaviours in a cohort of street recruited injecting drug users (IDUs) in Los Angeles County, between 1994 and 1996.
During the study period, 513 street recruited African-American and Latino IDUs were screened for syphilis and antibodies to HIV. Subjects were administered a risk behaviour survey at baseline and followed up at 6 month intervals for 18 months with repeated interviews and serological screening. Rate ratios were used to examine associations between syphilis incidence and demographic characteristics and risk behaviours. A proportional hazard model was used to identify predictors of syphilis incidence independent of demographic characteristics.
74% of the sample were male, 70% African-American, 30% Latino; and the median age was 43 years. Overall baseline serological prevalence of HIV was 2.5% and of syphilis 5.7%. None of the participants were co-infected for HIV and syphilis at baseline or at any of the 6 month follow ups. Among 390 eligible IDUs retained for analysis of incidence data, the overall syphilis incidence was 26.0 per 1000 person years. Higher syphilis incidence was found for women compared with men (RR = 2.70; 95% CI 1.60, 4.55), and for those 44 years of age or younger compared with those 45 years of age and older (RR = 2.26; 95% CI 1.25, 4.08). African-Americans were more likely to be syphilis incident cases when compared with Latinos, although the difference did not reach statistical significance (RR = 1.27; 95% CI 0.72, 2.23). In bivariate analysis, risk behaviours significantly associated with higher syphilis incidence included injection of cocaine, "speedball" and heroin, "crack" smoking, recency of first injection event, backloading of syringes, injecting with others, exchanging drugs or money for sex, multiple sex partners, and non-heterosexual sexual preference. Variables that significantly predicted syphilis infection at follow up in the multivariate analysis included multiple sex partners (RR = 7.8; 95% CI 2.4, 25.0), exchanging money for sex (RR = 3.0; 95% CI 0.9, 9.6), and recent initiation to injection drug use (RR = 4.6; 95% CI 1.1, 18.8).
Syphilis transmission among IDUs in Los Angeles County remains a serious public health concern, particularly among IDUs who engage in trading of sex for money or drugs. Although low, the prevalence of HIV observed in this study constitutes a serious concern because of the potential for expanded HIV transmission in this susceptible population of IDUs with high syphilis incidence. Enhanced case finding screening efforts and prevention of transmission of sexually transmitted infections should specifically target hard to reach IDUs and their sexual partners.
描述1994年至1996年间在洛杉矶县一组街头招募的注射吸毒者（IDU）中艾滋病毒（HIV）的流行情况以及梅毒发病率与性传播和药物注射风险行为之间的关联。
在研究期间，对513名街头招募的非裔美国人和拉丁裔注射吸毒者进行梅毒和HIV抗体筛查。受试者在基线时接受风险行为调查，并每隔6个月进行一次随访，为期18个月，期间进行重复访谈和血清学筛查。比率比用于检验梅毒发病率与人口统计学特征和风险行为之间的关联。使用比例风险模型来确定独立于人口统计学特征的梅毒发病率预测因素。
样本中74%为男性，70%为非裔美国人，30%为拉丁裔；中位年龄为43岁。HIV的总体基线血清学患病率为2.5%，梅毒为5.7%。在基线或任何6个月随访中，没有参与者同时感染HIV和梅毒。在390名保留用于发病率数据分析的合格注射吸毒者中，梅毒的总体发病率为每1000人年26.0例。女性的梅毒发病率高于男性（RR = 2.70；95% CI 1.60，4.55），44岁及以下者高于45岁及以上者（RR = 2.26；95% CI 1.25，4.08）。与拉丁裔相比，非裔美国人更有可能是梅毒发病病例，尽管差异未达到统计学显著性（RR = 1.27；95% CI 0.72，2.23）。在双变量分析中，与较高梅毒发病率显著相关的风险行为包括注射可卡因、“速球”和海洛因、吸食“快克”、首次注射事件的近期性、注射器回抽、与他人共用注射器、用毒品或金钱交换性行为、多个性伴侣以及非异性恋性取向。多变量分析中显著预测随访时梅毒感染的变量包括多个性伴侣（RR = 7.8；95% CI 2.4，25.0）、用金钱交换性行为（RR = 3.0；95% CI 0.9，9.6）以及最近开始注射吸毒（RR = 4.6；95% CI 1.1，18.8）。
洛杉矶县注射吸毒者中的梅毒传播仍然是一个严重的公共卫生问题，特别是在那些用性交换金钱或毒品的注射吸毒者中。尽管本研究中观察到的HIV患病率较低，但由于在梅毒发病率高的这一易感注射吸毒者人群中存在HIV传播扩大的可能性，这一情况仍令人严重关切。加强病例发现筛查工作以及预防性传播感染的传播应特别针对难以接触到的注射吸毒者及其性伴侣。
