McChrystal Ryan, Lees Jennifer, Gillies Katie, McAllister David, Hanlon Peter
School of Health and Wellbeing, University of Glasgow, Clarice Pears Building, 90 Byres Road, Glasgow, G12 8TB, UK.
School of Cardiovascular and Metabolic Health, University of Glasgow, BHF Glasgow Cardiovascular Research Centre, 126 University Avenue, Glasgow, G12 8TA, UK.
Trials. 2025 Mar 12;26(1):84. doi: 10.1186/s13063-025-08794-x.
Trial attrition poses several risks for the validity of randomised controlled trials (RCTs). To better understand attrition, studies have explored and identified predictors among participant and trial characteristics. Reviews of these have so far been limited to single conditions. We performed an umbrella review to explore which participant and trial characteristics are reported in predictive analyses of trial attrition in systematic reviews of RCTs across multiple conditions.
We searched MEDLINE, Embase, Web of Science and the Online Resource for Research in Clinical TriAls for systematic reviews of RCTs that evaluated associations between participant/trial characteristics and attrition. We included quantitative systematic reviews of adult populations that evaluated any participant/trial characteristic and any attrition outcome. Review quality was appraised using R-AMSTAR. A review-level narrative synthesis was conducted.
We identified 88 reviews of RCTs evaluating characteristics associated with attrition. Included reviews encompassed 33 different conditions. Over half (50/88, 56.8%) were of RCTs for psychological conditions. All but one examined trial characteristics (87/88, 98.9%) and fewer than half (42/88, 47.7%) evaluated participant characteristics. Reviews typically reported on participant age (33/42, 78.6%), sex (29/42, 69.1%) and the type (13/42, 31%) or severity (10/42, 23.8%) of an index condition. Trial characteristics typically reported on were intervention type (56/87, 64.4%), intervention frequency/intensity (29/87, 33.3%), intervention delivery/format (26/87, 29.9%), trial duration (16/87, 18.4%), publication/reporting year (15/87, 17.2%) and sample size (15/87, 31.9%). Retention strategies were rarely reported (2/87, 2.3%). No characteristic was examined for every condition. Some reviews of certain conditions found that age (12/33, 36.4%), intervention type (29/56, 51.8%) and trial duration (9/16, 56.3%) were associated with attrition, but no characteristic was reportedly associated across multiple conditions.
Across conditions, reviews conducting predictive analyses of attrition in RCTs typically report on several characteristics. These are participant age, sex and the type or severity of index condition, as well as the type, frequency or intensity and delivery or format of a trial intervention, trial duration, publication/reporting year and sample size. Future studies should consider exploring these characteristics as a core set when evaluating predictive factors of attrition in RCTs across multiple conditions.
PROSPERO CRD42023398276.
试验损耗给随机对照试验（RCT）的有效性带来了若干风险。为了更好地理解损耗情况，研究已经在参与者和试验特征中探索并确定了预测因素。迄今为止，对这些研究的综述仅限于单一疾病。我们进行了一项伞状综述，以探究在针对多种疾病的RCT系统评价中，哪些参与者和试验特征在试验损耗的预测分析中有所报告。
我们检索了MEDLINE、Embase、科学网和临床研究在线资源，以查找评估参与者/试验特征与损耗之间关联的RCT系统评价。我们纳入了对成年人群的定量系统评价，这些评价评估了任何参与者/试验特征和任何损耗结局。使用R-AMSTAR评估综述质量。进行了综述层面的叙述性综合分析。
我们确定了88篇评估与损耗相关特征的RCT综述。纳入的综述涵盖33种不同疾病。超过一半（50/88，56.8%）是针对心理疾病的RCT。除一项外，所有综述都研究了试验特征（87/88，98.9%），不到一半（42/88，47.7%）评估了参与者特征。综述通常报告参与者年龄（33/42，78.6%）、性别（29/42，69.1%）以及索引疾病的类型（13/42，31%）或严重程度（10/42，23.8%）。通常报告的试验特征包括干预类型（56/87，64.4%）、干预频率/强度（29/87，33.3%）、干预实施方式/形式（26/87，29.9%）、试验持续时间（16/87，18.4%）、发表/报告年份（15/87，17.2%）和样本量（15/最大尺寸，31.体积）。保留策略很少被报告（2/87，2.3%）。并非每种疾病都研究了所有特征。对某些疾病的一些综述发现，年龄（12/33，36.4%）、干预类型（29/56，51.8%）和试验持续时间（9/16，56.3%）与损耗有关，但据报道没有特征在多种疾病中都与损耗有关。
在多种疾病中，对RCT损耗进行预测分析的综述通常报告了若干特征。这些特征包括参与者年龄、性别以及索引疾病的类型或严重程度，还有试验干预的类型、频率或强度以及实施方式或形式、试验持续时间、发表/报告年份和样本量。未来的研究在评估多种疾病的RCT损耗预测因素时，应考虑将这些特征作为核心组进行探索。
PROSPERO CRD42023398276 。
