Sordo Luis, Bravo Maria J, Barrio Gregorio, Indave B Iciar, Degenhardt Louisa, Pastor-Barriuso Roberto
National Center for Epidemiology, Carlos III Institute of Health, Madrid, Spain.
Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP), Madrid, Spain.
Addiction. 2015 Aug;110(8):1247-57. doi: 10.1111/add.12940. Epub 2015 Jun 2.
A systematic review and meta-analysis were conducted to synthesize results from cohort studies on initiation into drug injection among vulnerable populations, to quantify heterogeneity in the estimated incidence rates of drug injection and to identify potential sources of heterogeneity and bias.
MEDLINE, EMBASE, PsycINFO and LILACS were searched for relevant studies published between 1980 and 2012. Investigators independently reviewed studies for inclusion, retrieved information on baseline population characteristics and follow-up features and assessed study quality. Study-specific incidence rates of drug injection were calculated as the number of new injectors divided by the person-years at risk. The I(2) statistic was used to quantify heterogeneity in incidence rates across studies, and random-effects meta-regression models were used to identify determinants of heterogeneity and bias.
Nine cohorts totalling 1843 participants met the inclusion criteria, with individual sample sizes of 70-415 participants and follow-up lengths of 6 months-3.4 years. The incidence of drug injection varied widely, from 2.1 to 24.2 cases per 100 person-years. The strong between-study heterogeneity (I(2) = 90%, P<0.001) was reduced significantly after accounting for the different follow-up lengths (I(2) = 17%, P = 0.30), with a 57% (95% confidence interval 46-66%) decrease in the pooled incidence of drug injection per 1-year increase in average follow-up.
The incidence of drug injection decreases sharply with increasing follow-up length in cohort studies on drug injection initiation. Low retention rates and potential for downward selection bias in cohort studies on drug injection initiation are caused primarily by greater loss to follow-up among individuals at higher risk of starting injection, compared with other participants.
进行一项系统综述和荟萃分析，以综合脆弱人群中药物注射起始情况队列研究的结果，量化药物注射估计发病率的异质性，并确定异质性和偏倚的潜在来源。
检索MEDLINE、EMBASE、PsycINFO和LILACS数据库，查找1980年至2012年期间发表的相关研究。研究人员独立审查研究以确定纳入情况，获取基线人群特征和随访特征信息，并评估研究质量。将新注射者数量除以风险人年数，计算各研究中药物注射的特定发病率。使用I²统计量量化各研究发病率的异质性，并使用随机效应荟萃回归模型确定异质性和偏倚的决定因素。
共有9个队列，总计1843名参与者符合纳入标准，单个样本量为7至415名参与者，随访时长为6个月至3.4年。药物注射发病率差异很大，每100人年为2.1至24.2例。在考虑不同随访时长后，研究间的强异质性（I² = 90%，P<0.001）显著降低（I² = 17%，P = 0.30），平均随访每增加1年，药物注射合并发病率降低57%（95%置信区间46 - 66%）。
在药物注射起始情况队列研究中，随着随访时长增加，药物注射发病率急剧下降。药物注射起始情况队列研究中低保留率和潜在的向下选择偏倚主要是由于与其他参与者相比，开始注射风险较高的个体失访情况更多。
