Target and actual sample sizes for studies from two trial registries from 1999 to 2020: an observational study
Target and actual sample sizes for studies from two trial registries from 1999 to 2020: an observational study
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DOI：
10.1136/bmjopen-2021-053377
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发表时间：
2021-12-24
期刊：
影响因子：
2.9
通讯作者：
Glasziou P
中科院分区：
文献类型：
--
作者：
Barnett AG;Glasziou P
调查目标样本量和实际样本量之间的差异，以及哪些研究特征与样本量有关。观察性研究。截至2021年的大型临床试验注册(从1999年开始)和ANZCTR(从2005年开始)。超过28万项干预性研究，不包括因安全原因而被扣留、终止或扩大准入的研究。实际样本量和目标样本量，以及实际样本量与目标样本量的研究内比率。大多数研究都是小规模的：两个数据库中实际样本量的中位数分别为60和52。随着时间的推移，目标样本量每5年减少9%-10%，实际样本量每5年减少18%-21%。实际样本量与目标样本量的比率每5年降低4.1%，这意味着更多的研究(平均而言)未能达到目标样本量。登记的研究往往比过度招募更少，令人担忧的是，目标样本量和实际样本量似乎都随着时间的推移而减少，目标样本量和实际样本量之间的研究内差距也是如此。样本量的减少和对动力不足研究的持续担忧意味着，需要对障碍和促进者进行更多研究，以改善招聘和获取数据。
To investigate differences between target and actual sample sizes, and what study characteristics were associated with sample sizes. Observational study. The large trial registries of clinicaltrials.gov (starting in 1999) and ANZCTR (starting in 2005) through to 2021. Over 280 000 interventional studies excluding studies that were withheld, terminated for safety reasons or were expanded access. The actual and target sample sizes, and the within-study ratio of the actual to target sample size. Most studies were small: the median actual sample sizes in the two databases were 60 and 52. There was a decrease over time in the target sample size of 9%–10% per 5 years, and a larger decrease of 18%–21% per 5 years for the actual sample size. The actual-to-target sample size ratio was 4.1% lower per 5 years, meaning more studies (on average) failed to hit their target sample size. Registered studies are more often under-recruited than over-recruited and worryingly both target and actual sample sizes appear to have decreased over time, as has the within-study gap between the target and actual sample size. Declining sample sizes and ongoing concerns about underpowered studies mean more research is needed into barriers and facilitators for improving recruitment and accessing data.
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