Estimating the Number of Persons Who Inject Drugs in the United States by Meta-Analysis to Calculate National Rates of HIV and Hepatitis C Virus Infections

BackgroundInjection drug use provides an efficient mechanism for transmitting bloodborne viruses, including human immunodeficiency virus (HIV) and hepatitis C virus (HCV). Effective targeting of resources for prevention of HIV and HCV infection among persons who inject drugs (PWID) is based on knowledge of the population size and disparity in disease burden among PWID. This study estimated the number of PWID in the United States to calculate rates of HIV and HCV infection.MethodsWe conducted meta-analysis using data from 4 national probability surveys that measured lifetime (3 surveys) or past-year (3 surveys) injection drug use to estimate the proportion of the United States population that has injected drugs. We then applied these proportions to census data to produce population size estimates. To estimate the disease burden among PWID by calculating rates of disease we used lifetime population size estimates of PWID as denominators and estimates of HIV and HCV infection from national HIV surveillance and survey data, respectively, as numerators. We calculated rates of HIV among PWID by gender-, age-, and race/ethnicity.ResultsLifetime PWID comprised 2.6% (95% confidence interval: 1.8%–3.3%) of the U.S. population aged 13 years or older, representing approximately 6,612,488 PWID (range: 4,583,188–8,641,788) in 2011. The population estimate of past-year PWID was 0.30% (95% confidence interval: 0.19 %–0.41%) or 774,434 PWID (range: 494,605–1,054,263). Among lifetime PWID, the 2011 HIV diagnosis rate was 55 per 100,000 PWID; the rate of persons living with a diagnosis of HIV infection in 2010 was 2,147 per 100,000 PWID; and the 2011 HCV infection rate was 43,126 per 100,000 PWID.ConclusionEstimates of the number of PWID and disease rates among PWID are important for program planning and addressing health inequities.

背景：注射毒品行为是包括人类免疫缺陷病毒（human immunodeficiency virus, HIV）、丙型肝炎病毒（hepatitis C virus, HCV）在内的血源性病原体传播的高效途径。针对注射药物使用者（persons who inject drugs, PWID）开展HIV、HCV感染预防的资源优化配置，需基于该人群规模及其疾病负担差异的科学认知。本研究旨在估算美国境内PWID的总数量，以此计算HIV与HCV的感染率。
方法：本研究采用4项全国概率抽样调查数据开展元分析（meta-analysis）：其中3项调查统计了研究对象的终生注射毒品行为，剩余3项统计了过去一年的注射毒品行为，以此估算美国境内曾有注射毒品行为的人群占总人口的比例。随后将上述比例代入全国人口普查数据，得到PWID的人群规模估算值。为通过疾病率计算评估PWID的疾病负担，本研究以PWID的终生人群规模估算值作为分母，分别以全国HIV监测数据与调查获得的HCV感染估算值作为分子。同时按性别、年龄、种族/族裔分层计算PWID的HIV感染率。
结果：2011年，美国13岁及以上人群中，终生有注射毒品行为的PWID占比为2.6%（95%置信区间（confidence interval）：1.8%~3.3%），对应人群规模约6612488人（区间范围：4583188~8641788人）；过去一年有注射毒品行为的PWID人群估算规模为0.30%（95%置信区间：0.19%~0.41%），即约774434人（区间范围：494605~1054263人）。在终生有注射毒品行为的PWID中，2011年HIV诊断率为每10万名PWID中55例；2010年确诊HIV感染者的现患率为每10万名PWID中2147例；2011年HCV感染率为每10万名PWID中43126例。
结论：PWID人群规模及该人群疾病率的估算结果，对于公共卫生项目规划与解决健康公平性问题均具有重要意义。