背景:多利益相关方德尔菲调查的最小样本量仍未得到充分研究。从三项大型国际多利益相关方德尔菲调查中得出,本研究旨在:1)研究增加样本量对结果可复制性的影响;2)评估结果的可复制性水平是否与参与者特征不同:例如,性别,年龄,专业。
方法:我们使用来自Delphi调查的数据来制定改进医疗干预试验报告的指南:SPIRIT(标准方案项目:干预试验建议)和CONSORT(报告试验综合标准)扩展替代终点(n=175,22项评级);CONSORT-SPI,社会和心理干预的扩展(n=333,评级77项);烧伤护理的核心结果集(n=553,评级88项)。在三项调查中,使用带替换的重新采样从参与者数据集中抽取随机子样本。对于每个子样本,计算所有评级调查项目的中位数,并与全部参与者数据集的中位数进行比较.使用所复制的中值数目(和四分位间距)来计算可复制性百分比(和变异性)。高可复制性定义为≥80%,中等为60%和<80%结果:在样本大小为60的情况下,三个数据集的平均可复制性(变异性)占项目总数的百分比为81%(10%)。在其中一个数据集(CONSORT-SPI)中,当样本量为80时,可复制性达到≥80%.平均而言,将样本量从80增加到160,结果的可复制性又增加了3%,变异性降低了1%.对于基于参与者特征的亚组分析(如性别、年龄,专业角色),使用20至100的重采样样本显示,20至30的样本量导致64%至77%的中等复制水平。
结论:我们发现,在多利益相关者德尔菲调查中,60至80名参与者的最小样本量在结果中提供了高水平的可复制性(≥80%)。对于仅限于个别利益相关者群体的德尔福研究(如研究人员,临床医生,病人),每组20到30个样本就足够了。
OBJECTIVE: The minimum sample size for multistakeholder Delphi surveys remains understudied. Drawing from three large international multistakeholder Delphi surveys, this study aimed to: 1) investigate the effect of increasing sample size on replicability of results; 2) assess whether the level of replicability of results differed with participant characteristics: for example, gender, age, and profession.
METHODS: We used data from Delphi surveys to develop guidance for improved reporting of health-care intervention trials: SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) and CONSORT (Consolidated Standards of Reporting Trials) extension for surrogate end points (n = 175, 22 items rated); CONSORT-SPI [CONSORT extension for Social and Psychological Interventions] (n = 333, 77 items rated); and core outcome set for burn care (n = 553, 88 items rated).
Resampling with replacement was used to draw random subsamples from the participant data set in each of the three surveys. For each subsample, the median value of all rated survey items was calculated and compared to the medians from the full participant data set. The median number (and interquartile range) of medians replicated was used to calculate the percentage replicability (and variability). High replicability was defined as ≥80% and moderate as 60% and <80% RESULTS: The average median replicability (variability) as a percentage of total number of items rated from the three datasets was 81% (10%) at a sample size of 60. In one of the datasets (CONSORT-SPI), a ≥80% replicability was reached at a sample size of 80. On average, increasing the sample size from 80 to 160 increased the replicability of results by a further 3% and reduced variability by 1%. For subgroup analysis based on participant characteristics (eg, gender, age, professional role), using resampled samples of 20 to 100 showed that a sample size of 20 to 30 resulted to moderate replicability levels of 64% to 77%.
CONCLUSIONS: We found that a minimum sample size of 60-80 participants in multistakeholder Delphi surveys provides a high level of replicability (≥80%) in the results. For Delphi studies limited to individual stakeholder groups (such as researchers, clinicians, patients), a sample size of 20 to 30 per group may be sufficient.