Background

The synchronised monthly disbursement of income assistance, whereby all recipients are paid on the same day, has been associated with increases in illicit drug use and serious associated harms. This phenomenon is often referred to as the cheque effect. Because payment variability can affect consumption patterns, this study aimed to assess whether these harms could be mitigated through a structural intervention that varied income assistance payment timing and frequency.

Methods

This randomised, parallel group trial was done in Vancouver, Canada, and enrolled recipients of income assistance whose drug use increased around payment days. The recipients were randomly assigned 1:2:2 to a control group that received monthly synchronised income assistance payments on government payment days, a staggered group in which participants received single desynchronised monthly income assistance payments, or a split and staggered group in which participants received desynchronised income assistance payments split into two instalments per month, 2 weeks apart, for six monthly payment cycles. Desynchronised payments in the intervention groups were made on individual payment days outside the week of the standard government schedules. Randomisation was through a pre-established stratified block procedure. Investigators and statisticians were masked to group allocation, but participants and front-line staff were not. Complete final results are reported after scheduled interim analyses and the resulting early stoppage of recruitment. Under intention-to-treat specifications, generalised linear mixed models were used to analyse the primary outcome, which was escalations in drug use, predefined as a 40% increase in at least one of: use frequency; use quantity; or number of substances used during the 3 days after government payments. Secondary analyses examined analogous drug use outcomes coinciding with individual payments as well as exposure to violence. This trial is registered with ClinicalTrials.gov, NCT02457949.

Findings

Between Oct 27, 2015, and Jan 2, 2019, 45 participants were enrolled to the control group, 72 to the staggered group, and 77 to the split and staggered group. Intention-to-treat analyses showed a significantly reduced likelihood of increased drug use coinciding with government payment days, relative to the control group, in the staggered (adjusted odds ratio 0·38, 95% CI 0·20–0·74; p=0·0044) and split and staggered (0·44, 0·23–0·83; p=0·012) groups. Findings were consistent in the secondary analyses of drug use coinciding with individual payment days (staggered group 0·50, 0·27–0·96, p=0·036; split and staggered group 0·49, 0·26–0·94, p=0·030). However, secondary outcome analyses of exposure to violence showed increased harm in the staggered group compared with the control group (2·71, 1·06–6·91, p=0·037). Additionally, 51 individuals had a severe or life-threatening adverse event and there were six deaths, none of which was directly attributed to study participation.

Interpretation

Complex results indicate the potential for modified income assistance payment schedules to mitigate escalations in drug use, provided measures to address unintended harms are also undertaken. Additional research is needed to clarify whether desynchronised schedules produce other unanticipated consequences and if additional measures could mitigate these harms.

Funding

Canadian Institutes of Health Research, Providence Health Care Research Institute, Peter Wall Institute for Advanced Research, Michael Smith Foundation for Health Research.

中文翻译：

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替代性收入援助计划对吸毒和与毒品有关的危害的影响：一项随机对照试验

背景

每月同步发放收入援助，使所有受助人都在同一天付款，这与非法药物使用增加和严重的相关危害有关。这种现象通常称为检查效果。由于支付的可变性会影响消费模式，因此本研究旨在评估是否可以通过改变收入援助支付时间和频率的结构性干预措施来减轻这些危害。

方法

这项随机平行小组试验在加拿大温哥华进行，招募了收入援助的接受者，这些人的药物使用在支付日左右有所增加。接受者被随机分配为一个1：2：2的对照组，一个对照组在政府付款日接收每月同步收入援助金，一个交错组，其中参与者接收单次不同步的每月收入援助金，或者一个分散和交错的组，其中参与者收到非同步收入援助付款分为两个月，每月分两次，相隔两周，共六个月。干预组中的不同步付款是在标准政府时间表的一周之外的各个付款日进行的。通过预先建立的分层阻断程序进行随机化。调查人员和统计人员被掩盖在小组分配中，但参与者和一线人员则没有。在计划的中期分析以及由此导致的提前停工之后，将报告完整的最终结果。在意向性治疗规范下，使用广义线性混合模型来分析主要结局，即药物使用的增加，预定义为至少以下一项增加40％：使用频率；使用量 或政府付款后3天内使用的物质数量。二级分析检查了与个人付款以及暴力暴露相吻合的类似药物使用结果。该试验已在ClinicalTrials.gov（NCT02457949）上注册。在计划的中期分析以及由此导致的提前停工之后，将报告完整的最终结果。在意向性治疗规范下，使用广义线性混合模型来分析主要结局，即药物使用的增加，预定义为至少以下一项增加40％：使用频率；使用量 或政府付款后3天内使用的物质数量。二级分析检查了与个人付款以及暴力暴露相吻合的类似药物使用结果。该试验已在ClinicalTrials.gov（NCT02457949）上注册。在计划的中期分析以及由此导致的提前停工之后，将报告完整的最终结果。在意向性治疗规范下，使用广义线性混合模型来分析主要结局，即药物使用的增加，预定义为至少以下一项增加40％：使用频率；使用量 或政府付款后3天内使用的物质数量。二级分析检查了与个人付款以及暴力暴露相吻合的类似药物使用结果。该试验已在ClinicalTrials.gov（NCT02457949）上注册。预定义为至少以下一项增加40％：使用频率；使用量 或政府付款后3天内使用的物质数量。二级分析检查了与个人付款以及暴力暴露相吻合的类似药物使用结果。该试验已在ClinicalTrials.gov（NCT02457949）上注册。预定义为至少以下一项增加40％：使用频率；使用量 或政府付款后3天内使用的物质数量。二级分析检查了与个人付款以及暴力暴露相吻合的类似药物使用结果。该试验已在ClinicalTrials.gov（NCT02457949）上注册。

发现

在2015年10月27日至2019年1月2日之间，有45名参与者参加了对照组，有72名参加了交错小组，有77名参加了分裂和交错小组。意向治疗分析显示，与对照组相比，在交错状态下（调整后的优势比为0·38、95％CI 0·20-0·74； p），与政府支付天数相符的药物使用增加的可能性大大降低。 = 0·0044）并拆分和交错（0·44，0·23-0.83; p = 0·012）组。在药物使用的二次分析中，发现与单个付款日​​相吻合（交错组0·50、0·27-0.96，p = 0·036；拆分交错组0·49、0·26-0。····················································· 94，p = 0·030）。但是，对暴力行为的次要结果分析显示，与对照组相比，交错组的伤害增加（2·71、1·06-6·91，p = 0·037）。此外，

解释

复杂的结果表明，如果还采取了解决意外伤害的措施，则有可能修改收入援助付款时间表以减轻药物使用量的上升。需要进行进一步的研究，以弄清不同步的时间表是否会产生其他无法预料的后果，以及是否可以采取其他措施来减轻这些危害。

资金

加拿大卫生研究所，普罗维登斯卫生保健研究所，彼得沃尔高级研究所，迈克尔·史密斯卫生研究所基金会。