Moore Carmel, Bolton Thomas, Walker Matthew, Kaptoge Stephen, Allen David, Daynes Michael, Mehenny Susan, Sambrook Jennifer, Watkins Nicholas A, Miflin Gail, Di Angelantonio Emanuele, Ouwehand Willem H, Roberts David J, Danesh John, Thompson Simon G
Department of Public Health and Primary Care, University of Cambridge, Strangeways Research Laboratory, Worts Causeway, Cambridge, CB1 8RN, UK.
NIHR Blood and Transplant Research Unit in Donor Health and Genomics, Strangeways Research Laboratory, Worts Causeway, Cambridge, CB1 8RN, UK.
Trials. 2016 Sep 20;17(1):458. doi: 10.1186/s13063-016-1579-7.
The interpretation of trial results can be helped by understanding how generalisable they are to the target population for which inferences are intended. INTERVAL, a large pragmatic randomised trial of blood donors in England, is assessing the effectiveness and safety of reducing inter-donation intervals. The trial recruited mainly from the blood service's static centres, which collect only about 10 % of whole-blood donations. Hence, the extent to which the trial's participants are representative of the general blood donor population is uncertain. We compare these groups in detail.
We present the CONSORT flowchart from participant invitation to randomisation in INTERVAL. We compare the characteristics of those eligible and consenting to participate in INTERVAL with the general donor population, using the national blood supply 'PULSE' database for the period of recruitment. We compare the characteristics of specific groups of trial participants recruited from different sources, as well as those who were randomised versus those not randomised.
From a total of 540,459 invitations, 48,725 donors were eligible and consented to participate in INTERVAL. The proportion of such donors varied from 1-22 % depending on the source of recruitment. The characteristics of those consenting were similar to those of the general population of 1.3 million donors in terms of ethnicity, blood group distribution and recent deferral rates from blood donation due to low haemoglobin. However, INTERVAL participants included more men (50 % versus 44 %), were slightly older (mean age 43.1 versus 42.3 years), included fewer new donors (3 % versus 22 %) and had given more donations over the previous 2 years (mean 3.3 versus 2.2) than the general donor population. Of the consenting participants, 45,263 (93 %) donors were randomised. Compared to those not randomised, the randomised donors showed qualitatively similar differences to those described above.
There was broad similarity of participants in INTERVAL with the general blood donor population of England, notwithstanding some differences in age, sex and donation history. Any heterogeneity of the trial's results according to these characteristics will need to be studied to ensure its generalisability to the general donor population.
Current Controlled Trials ISRCTN24760606 . Registered on 25 January 2012.
了解试验结果对目标人群的可推广程度有助于对试验结果进行解读。“INTERVAL”是一项针对英格兰献血者的大型实用性随机试验，正在评估缩短献血间隔时间的有效性和安全性。该试验主要从血液服务的固定中心招募参与者，这些中心采集的全血仅占全血捐献量的10%左右。因此，试验参与者在多大程度上代表一般献血人群尚不确定。我们对这些群体进行了详细比较。
我们展示了“INTERVAL”试验从参与者邀请到随机分组的CONSORT流程图。我们利用招募期间的国家血液供应“PULSE”数据库，将符合条件并同意参与“INTERVAL”试验的参与者的特征与一般献血人群进行比较。我们比较了从不同来源招募的特定试验参与者群体的特征，以及随机分组者与未随机分组者的特征。
在总共540459份邀请中，有48725名献血者符合条件并同意参与“INTERVAL”试验。这类献血者的比例因招募来源而异，从1%到22%不等。在种族、血型分布以及近期因血红蛋白水平低而延期献血的比例方面，同意参与试验者的特征与130万一般献血人群的特征相似。然而，与一般献血人群相比，“INTERVAL”试验的参与者中男性更多（50%对44%），年龄稍大（平均年龄43.1岁对42.3岁），新献血者较少（3%对22%），并且在过去两年内献血次数更多（平均3.3次对2.2次）。在同意参与试验的参与者中，45263名（93%）献血者被随机分组。与未随机分组者相比，随机分组的献血者在质量上表现出与上述相似的差异。
尽管在年龄、性别和献血历史方面存在一些差异，但“INTERVAL”试验的参与者与英格兰一般献血人群大体相似。需要研究试验结果根据这些特征的任何异质性，以确保其对一般献血人群的可推广性。
当前受控试验ISRCTN24760606。于2012年1月25日注册。
