PDF(Pubmed)
Abstract：
BACKGROUND: High participant retention enhances the validity of clinical trials. A monetary incentive can increase retention, but it is not known if when it is provided and if it is conditional matters. We aimed to determine whether there was a difference in the number of follow-up trial questionnaires returned when a monetary (gift voucher) incentive was given to participants at recruitment (non-conditional), compared to informing participants at recruitment that the incentive would be given only once their 14-day daily diary (questionnaire) had been returned (conditional).
METHODS: A cluster randomised study within a trial embedded within the Antivirals for influenza-Like Illness, An rCt of Clinical and Cost effectiveness in primary CarE (ALIC4E) Trial. Matched site pairs (GP practices) were randomised using computer-generated random numbers, to either a non-conditional or conditional monetary voucher incentive (only once their 14-day daily diary (questionnaire) had been returned. Sites were matched on previous recruitment levels and practice list size. Analyses were conducted according to randomised groups irrespective of compliance with a two-sided 5% level statistical significance level. The main analysis of the primary outcome (site proportion of diaries returned) was linear regression accounting for site pair (using cluster-robust variance). Additional weighted, paired and non-parametric sensitivity analyses were conducted. Secondary outcomes were the site average number of completed pages, time to return diary, and cost related to the incentive (administration and postage).
RESULTS: Of the 42 randomised sites (21 for each intervention), only 28 recruited at least one participant with only 10 practice pairs recruiting participants at both constituent sites. Raw diaries return proportions were 0.58 (127/220) and 0.73 (91/125) for non-conditional and conditional incentive groups. Regression analysis adjusted for site pair showed no significant difference in returns, - 0.09, (95% CI, - 0.29, 0.10, p = 0.34); when weighted, there was still no clear difference: 0.15 (95% CI, - 0.02, 0.31, p = 0.07). There was no clear statistical evidence of a difference in time taken to return questionnaires, nor the proportion of pages completed, by the intervention group in the main analyses (all p > 0.05). The conditional incentive was approximately £23 cheaper per diary returned based upon observed data.
CONCLUSIONS: There was no clear evidence of a statistically significant difference in the proportion of participant-completed diaries returned between conditional or non-conditional incentive groups. The time to questionnaire return and completeness of the returned questionnaires were similar in both groups. There was substantial statistical uncertainty in the findings. Some of the sensitivity analyses suggested that a meaningful benefit of a conditional incentive of a magnitude that would be meaningful was plausible. The conditional approach costs less in cash terms.
METHODS: A cluster randomised study within a trial embedded within the Antivirals for influenza-Like Illness, An rCt of Clinical and Cost effectiveness in primary CarE (ALIC4E) Trial. Matched site pairs (GP practices) were randomised using computer-generated random numbers, to either a non-conditional or conditional monetary voucher incentive (only once their 14-day daily diary (questionnaire) had been returned. Sites were matched on previous recruitment levels and practice list size. Analyses were conducted according to randomised groups irrespective of compliance with a two-sided 5% level statistical significance level. The main analysis of the primary outcome (site proportion of diaries returned) was linear regression accounting for site pair (using cluster-robust variance). Additional weighted, paired and non-parametric sensitivity analyses were conducted. Secondary outcomes were the site average number of completed pages, time to return diary, and cost related to the incentive (administration and postage).
RESULTS: Of the 42 randomised sites (21 for each intervention), only 28 recruited at least one participant with only 10 practice pairs recruiting participants at both constituent sites. Raw diaries return proportions were 0.58 (127/220) and 0.73 (91/125) for non-conditional and conditional incentive groups. Regression analysis adjusted for site pair showed no significant difference in returns, - 0.09, (95% CI, - 0.29, 0.10, p = 0.34); when weighted, there was still no clear difference: 0.15 (95% CI, - 0.02, 0.31, p = 0.07). There was no clear statistical evidence of a difference in time taken to return questionnaires, nor the proportion of pages completed, by the intervention group in the main analyses (all p > 0.05). The conditional incentive was approximately £23 cheaper per diary returned based upon observed data.
CONCLUSIONS: There was no clear evidence of a statistically significant difference in the proportion of participant-completed diaries returned between conditional or non-conditional incentive groups. The time to questionnaire return and completeness of the returned questionnaires were similar in both groups. There was substantial statistical uncertainty in the findings. Some of the sensitivity analyses suggested that a meaningful benefit of a conditional incentive of a magnitude that would be meaningful was plausible. The conditional approach costs less in cash terms.
摘要：
背景：高参与者保留率提高了临床试验的有效性。货币激励可以增加留存率，但不知道它是否在何时提供，是否有条件。我们的目的是确定在招募时（无条件）向参与者提供货币（礼品券）激励时返回的后续试验问卷数量是否存在差异，相比之下，在招募时告知参与者只有在他们14天的日记（问卷）被退回（有条件的）后才会给予奖励。
方法：一项纳入抗病毒药物治疗流感样疾病的试验中的集群随机研究，初级CarE（ALIC4E）试验的临床和成本效益。使用计算机生成的随机数对匹配的站点对（GP实践）进行随机化，非条件性或有条件性货币券激励(仅在他们14天的日记(问卷)被退回后。地点与以前的招聘水平和实践列表大小相匹配。根据随机分组进行分析，无论是否符合双侧5％水平的统计显着性水平。主要结果（返回日记的站点比例）的主要分析是考虑站点对的线性回归（使用聚类稳健方差）。额外加权，我们进行了配对和非参数敏感性分析.次要结果是网站平均完成页数，时间返回日记，以及与激励相关的成本(管理和邮费)。
结果：在42个随机站点（每个干预21个）中，只有28人招募了至少一名参与者，只有10个练习对在两个组成地点招募参与者。非条件和条件激励组的原始日记回报比例分别为0.58（127/220）和0.73（91/125）。调整位点对的回归分析显示，收益率没有显著差异，-0.09，(95%CI，-0.29，0.10，p=0.34)；加权后，仍然没有明显差异：0.15（95％CI，-0.02，0.31，p=0.07）。没有明确的统计证据表明返回问卷所需的时间存在差异，也不是完成的页面比例，在主要分析中，干预组(均p>0.05)。根据观察到的数据，每本日记返回的条件激励大约便宜23英镑。
结论：没有明确证据表明有条件或非条件激励组之间返回的参与者完成日记的比例存在统计学上的显着差异。两组的问卷返回时间和返回问卷的完整性相似。研究结果存在很大的统计不确定性。一些敏感性分析表明，有意义的有条件激励的有意义的好处是合理的。有条件法的现金成本较低。
方法：一项纳入抗病毒药物治疗流感样疾病的试验中的集群随机研究，初级CarE（ALIC4E）试验的临床和成本效益。使用计算机生成的随机数对匹配的站点对（GP实践）进行随机化，非条件性或有条件性货币券激励(仅在他们14天的日记(问卷)被退回后。地点与以前的招聘水平和实践列表大小相匹配。根据随机分组进行分析，无论是否符合双侧5％水平的统计显着性水平。主要结果（返回日记的站点比例）的主要分析是考虑站点对的线性回归（使用聚类稳健方差）。额外加权，我们进行了配对和非参数敏感性分析.次要结果是网站平均完成页数，时间返回日记，以及与激励相关的成本(管理和邮费)。
结果：在42个随机站点（每个干预21个）中，只有28人招募了至少一名参与者，只有10个练习对在两个组成地点招募参与者。非条件和条件激励组的原始日记回报比例分别为0.58（127/220）和0.73（91/125）。调整位点对的回归分析显示，收益率没有显著差异，-0.09，(95%CI，-0.29，0.10，p=0.34)；加权后，仍然没有明显差异：0.15（95％CI，-0.02，0.31，p=0.07）。没有明确的统计证据表明返回问卷所需的时间存在差异，也不是完成的页面比例，在主要分析中，干预组(均p>0.05)。根据观察到的数据，每本日记返回的条件激励大约便宜23英镑。
结论：没有明确证据表明有条件或非条件激励组之间返回的参与者完成日记的比例存在统计学上的显着差异。两组的问卷返回时间和返回问卷的完整性相似。研究结果存在很大的统计不确定性。一些敏感性分析表明，有意义的有条件激励的有意义的好处是合理的。有条件法的现金成本较低。
