Department of Health Services Research, Carl von Ossietzky University of Oldenburg, Ammerländer Heerstraße 114-118, 26129, Oldenburg, Germany.
Department of Health, Long-Term Care and Pensions, SOCIUM Research Center on Inequality and Social Policy, University of Bremen, Mary-Somerville-Straße 5, 28359, Bremen, Germany.
Trials. 2022 Jul 8;23(1):560. doi: 10.1186/s13063-022-06470-y.
The generalizability of randomized controlled trials (RCTs) with a low response can be limited by systematic differences between participants and nonparticipants. This participation bias, however, is rarely investigated because data on nonparticipants is usually not available. The purpose of this article is to compare all participants and nonparticipants of a RCT to improve oral health among home care recipients at baseline and during follow-up using claims data.
Seven German statutory health and long-term care insurance funds invited 9656 home care recipients to participate in the RCT MundPflege. Claims data for all participants (n = 527, 5.5% response) and nonparticipants (n = 9129) were analyzed. Associations between trial participation and sex, age, care dependency, number of Elixhauser diseases, and dementia, as well as nursing, medical, and dental care utilization at baseline, were investigated using multivariable logistic regression. Associations between trial participation and the probability of (a) moving into a nursing home, (b) being hospitalized, and (c) death during 1 year of follow-up were examined via Cox proportional hazards regressions, controlling for baseline variables.
At baseline, trial participation was positively associated with male sex (odds ratio 1.29 [95% confidence interval 1.08-1.54]), high (vs. low 1.46 [1.15-1.86]) care dependency, receiving occasional in-kind benefits to relieve caring relatives (1.45 [1.15-1.84]), having a referral by a general practitioner to a medical specialist (1.62 [1.21-2.18]), and dental care utilization (2.02 [1.67-2.45]). It was negatively associated with being 75-84 (vs. < 60 0.67 [0.50-0.90]) and 85 + (0.50 [0.37-0.69]) years old. For morbidity, hospitalizations, and formal, respite, short-term, and day or night care, no associations were found. During follow-up, participants were less likely to move into a nursing home than nonparticipants (hazard ratio 0.50 [0.32-0.79]). For hospitalizations and mortality, no associations were found.
For half of the comparisons, differences between participants and nonparticipants were observed. The RCT's generalizability is limited, but to a smaller extent than one would expect because of the low response. Routine data provide a valuable source for investigating potential differences between trial participants and nonparticipants, which might be used by future RCTs to evaluate the generalizability of their findings.
German Clinical Trials Register DRKS00013517 . Retrospectively registered on June 11, 2018.
低应答率的随机对照试验（RCT）的普遍性可能受到参与者和非参与者之间系统差异的限制。然而，这种参与偏差很少被调查，因为通常无法获得非参与者的数据。本文的目的是使用索赔数据比较 RCT 中所有的参与者和非参与者，以改善家庭护理接受者的口腔健康，基线和随访时。
七家德国法定健康和长期护理保险公司邀请了 9656 名家庭护理接受者参加 MundPflege RCT。对所有参与者（n=527，应答率为 5.5%）和非参与者（n=9129）的索赔数据进行了分析。使用多变量逻辑回归分析了试验参与与性别、年龄、护理依赖、Elixhauser 疾病数量和痴呆症以及护理、医疗和牙科护理利用之间的关系，基线时，通过 Cox 比例风险回归检验了试验参与与（a）搬入疗养院、（b）住院和（c）随访 1 年内死亡的概率之间的关系，控制了基线变量。
基线时，试验参与与男性（优势比 1.29 [95%置信区间 1.08-1.54]）、高度（vs. 低度 1.46 [1.15-1.86]）护理依赖、偶尔接受实物福利以减轻照顾亲属的负担（1.45 [1.15-1.84]）、由全科医生转介给医学专家（1.62 [1.21-2.18]）和牙科护理利用（2.02 [1.67-2.45]）呈正相关。与 75-84 岁（vs. <60 岁 0.67 [0.50-0.90]）和 85+岁（0.50 [0.37-0.69]）年龄呈负相关。对于发病率、住院和正式、临时、短期和日托或夜间护理，未发现关联。在随访期间，参与者搬入疗养院的可能性低于非参与者（风险比 0.50 [0.32-0.79]）。对于住院和死亡，没有发现关联。
对于一半的比较，观察到参与者和非参与者之间存在差异。RCT 的普遍性受到限制，但由于应答率低，限制程度要小一些。常规数据为调查试验参与者和非参与者之间的潜在差异提供了有价值的来源，未来的 RCT 可以利用这些差异来评估其研究结果的普遍性。
德国临床试验注册中心 DRKS00013517 。2018 年 6 月 11 日回顾性注册。
