National Drug Research Institute (NDRI), Faculty of Health Sciences, Curtin University, Melbourne, Australia.
Disease Elimination Head, Alcohol and other Drug Research, Burnet Institute, Melbourne, Australia.
BMC Med Res Methodol. 2024 Oct 30;24(1):257. doi: 10.1186/s12874-024-02377-1.
Compared to the general population, people who inject drugs have poor health and wellbeing. Longitudinal studies can provide insight into factors driving these worse health outcomes but are subject to methodological challenges, such as cohort attrition. The aim of this study was to assess and characterise attrition in a prospective cohort of people who inject drugs in Victoria, Australia.
Using annually collected self-reported data from The Melbourne Injecting Drug User Cohort Study (SuperMIX) from September 2008 to January 2021, we estimated the incidence of participants being lost-to-follow-up (LTFU), with an episode of being LTFU defined as participants not undertaking a follow-up interview within two years of their last interview. We utilised a multiple event discrete-time survival analysis on participant period-observation data to estimate the associations between key factors and LTFU. Key areas of exposure measurement in analyses were sociodemographic, drug use and mental health.
A total of n = 1328 SuperMIX participants completed a baseline interview, with n = 489 (36.8%) LTFU, i.e. not completing a follow-up interview in the following two years. Increased attrition was observed among SuperMIX participants who were: born outside Australia, younger than 30 years, reporting having completed fewer years of education, not residing in stable accommodation, not in stable employment and not on opioid agonist therapy (OAT).
The attrition rate of the SuperMIX cohort has largely been stable throughout the duration of the study. Higher attrition rates among individuals at greater sociodemographic disadvantage and not on OAT suggest that additional efforts are required to retain these participants. Findings also suggest that SuperMIX might not be capturing data on adverse health and wellbeing outcomes among subpopulations at high risk of harm.
与一般人群相比，吸毒者的健康和福利状况较差。纵向研究可以深入了解导致这些较差健康结果的因素，但存在方法学挑战，例如队列流失。本研究旨在评估和描述澳大利亚维多利亚州一个前瞻性吸毒者队列的流失情况。
使用 2008 年 9 月至 2021 年 1 月期间每年从墨尔本吸毒者队列研究（SuperMIX）中收集的自我报告数据，我们估计了参与者失去随访（LTFU）的发生率，将 LTFU 定义为参与者在上一次访谈后的两年内未进行随访访谈。我们利用参与者期间观察数据的多事件离散时间生存分析来估计关键因素与 LTFU 之间的关联。分析中暴露测量的关键领域包括社会人口统计学、吸毒和心理健康。
共有 1328 名 SuperMIX 参与者完成了基线访谈，其中 489 名（36.8%）流失，即在接下来的两年内未完成随访访谈。在 SuperMIX 参与者中，观察到更高的流失率：出生在澳大利亚境外、年龄小于 30 岁、报告完成的教育年限较少、未居住在稳定住所、未稳定就业且未接受阿片类激动剂治疗（OAT）。
SuperMIX 队列的流失率在研究期间基本保持稳定。在社会人口统计学劣势较大且未接受 OAT 的个体中，更高的流失率表明需要付出更多努力来留住这些参与者。研究结果还表明，SuperMIX 可能无法收集高危人群不良健康和福利结果的数据。
