Supplementary Material for: Brief Online Cognitive Behavioural Intervention for Dysfunctional Worry Related to the COVID-19 Pandemic: A Randomised Controlled Trial

<b><i>Introduction:</i></b> Worries about the immediate and long-term consequences of the COVID-19 pandemic may for some individuals develop into pervasive worry that is disproportionate in its intensity or duration and significantly interferes with everyday life. <b><i>Objective:</i></b> The aim of this study was to investigate if a brief self-guided, online psychological intervention can reduce the degree of dysfunctional worry related to the COVID-19 pandemic and associated symptoms. <b><i>Methods:</i></b> 670 adults from the general Swedish general population reporting daily uncontrollable worry about CO­VID-19 and its possible consequences (e.g., illness, death, the economy, one’s family) were randomised (1:1 ratio) to a 3-week self-guided, online cognitive behavioural intervention targeting dysfunctional COVID-19 worry and associated symptoms, or a waiting list of equal duration. The primary outcome measure was a COVID-19 adapted version of the Generalised Anxiety Disorder 7-item scale administered at baseline and weeks 1–3 (primary endpoint). Follow-up assessments were conducted 1 month after treatment completion. The trial was registered on ClinicalTrials.gov (NCT04341922) before inclusion of the first participant. <b><i>Results:</i></b> The main pre-specified intention-to-treat analysis indicated significant reductions in COVID-19-related worry for the intervention group compared to the waiting list (β = 1.14, <i>Z</i> = 9.27, <i>p</i> &lt; 0.001), corresponding to a medium effect size (bootstrapped <i>d</i> = 0.74 [95% CI: 0.58–0.90]). Improvements were also seen on all secondary measures, including mood, daily functioning, insomnia, and intolerance of uncertainty. Participant satisfaction was high. No serious adverse events were recorded. <b><i>Conclusions:</i></b> A brief digital and easily scalable self-guided psychological intervention can significantly reduce dysfunctional worry and associated behavioural symptoms related to the COVID-19 pandemic.

<b><i>引言：</i></b> 对于部分个体而言，对新型冠状病毒肺炎（COVID-19）大流行的即时及长期后果的担忧，可能发展为与实际情况不成比例的弥散性过度担忧，并显著干扰其日常生活。<b><i>研究目的：</i></b> 本研究旨在探讨一项简短的自助式线上心理干预措施，能否减轻与COVID-19大流行相关的功能失调性担忧及其伴随症状。<b><i>研究方法：</i></b> 本研究纳入670名来自瑞典普通人群的成年受试者，这些受试者均报告存在每日无法自控的COVID-19相关担忧，且担忧涉及该疫情可能带来的各类后果（如患病、死亡、经济状况、个人家庭等）。受试者按1:1的比例随机分为两组：一组接受为期3周的自助式线上认知行为干预，该干预针对COVID-19相关功能失调性担忧及其伴随症状；另一组为同等时长的等待对照组。本研究的主要结局指标为在基线及第1~3周时施测的、适配COVID-19的广泛性焦虑障碍7条目量表（Generalised Anxiety Disorder 7-item scale）（主要终点）。在治疗结束1个月后，对受试者进行随访评估。本试验在首例受试者入组前，已在ClinicalTrials.gov平台完成注册（注册号：NCT04341922）。<b><i>研究结果：</i></b> 预先设定的主要意向性治疗分析结果显示，与等待对照组相比，干预组的COVID-19相关担忧程度显著降低（β=1.14，<i>Z</i>=9.27，<i>p</i>&lt;0.001），对应中等效应量（bootstrap校正后的效应量<i>d</i>=0.74，95%置信区间：0.58~0.90）。所有次要结局指标均观察到显著改善，包括情绪状态、日常功能、失眠症状及不确定性不耐受水平。受试者对干预措施的满意度较高，且未记录到严重不良事件。<b><i>研究结论：</i></b> 一项简短的数字化、易于推广的自助式心理干预措施，可显著减轻与COVID-19大流行相关的功能失调性担忧及其伴随行为症状。