a Endocrinology, Diabetology and Metabolism, Department of Internal Medicine, University Hospital Basel, Switzerland / Department of Clinical Research, University of Basel, Switzerland.
Bürgerspital Solothurn, Switzerland.
Swiss Med Wkly. 2019 Jul 24;149:w20114. doi: 10.4414/smw.2019.20114. eCollection 2019 Jul 15.
AIM OF THE STUDY: The internal validity of double blinding in randomised placebo-controlled trials (RCTs) has become a target of criticism. The goal of this study was to investigate (a) how accurately the patients and their treating physicians were able to guess their assigned treatment, and (b) predictors for an accurate guess.
Data on treatment estimation from patients (n = 382) and their physicians (n = 358 guesses) in an RCT investigating the role of adjunct prednisone for community-acquired pneumonia in a tertiary care setting were analysed. At discharge, patients and their physicians had to guess whether they had been assigned to the prednisone or to the placebo group. The alternative possibility was “uncertain”. Percentages and confidence intervals (CIs) were calculated for the proportion of patients guessing correctly. Chance finding was defined as having 50% or less correct guesses. To test for predictors for prednisone treatment guess, a mixed effects logistic regression model was performed.
In the prednisone group, 28.9% (55/190; 95% CI 22.6–36.0%) of the patients made a correct guess and the majority (61.6%, 117/190) was uncertain. In the placebo group, 13.0% (25/192; 95% CI 8.8–18.8%) guessed correctly, with the majority being uncertain (69.8%, 134/192). Physicians guessed correctly in 48.3% (87/180, 95% CI 40.8–55.9%) of cases in the prednisone group and in 66.3% (118/178, 95% CI 58.8–73.2%) of cases in the placebo group, which was above chance for the placebo group. The physicians were uncertain in 21.7% (39/180) of cases in the prednisone group, and in 15.2% (27/178) of cases in the placebo group. Significant predictors for guessing prednisone were the occurrence of hyperglycaemia (odds ratio [OR] 3.77, 95% CI 2.39–5.95; p<0.001) and a shorter time to clinical stability (OR 0.95, 95% CI 0.91–0.99; p = 0.02).
We confirmed that patient blinding was achieved in this study. Physicians made correct guesses more often than patients. Treatment estimation by both patients and physicians was led not only by the expectations of treatment effects of the study drug but also by known side effects of prednisone. Trial registration no.: NCT00973154  .
随机安慰剂对照试验（RCT）的双盲内部有效性已成为批评的目标。本研究的目的是调查：（a）患者及其治疗医生猜测其分配治疗的准确性；（b）准确猜测的预测因素。
分析了在三级保健环境中研究辅助泼尼松在社区获得性肺炎中的作用的 RCT 中，患者（n=382）和他们的医生（n=358 次猜测）的治疗估计数据。出院时，患者及其医生必须猜测他们是否被分配到泼尼松组或安慰剂组。另一种可能性是“不确定”。计算了正确猜测的患者比例的百分比和置信区间（CI）。机会发现定义为正确猜测的比例低于 50%。为了测试预测泼尼松治疗猜测的因素，进行了混合效应逻辑回归模型。
在泼尼松组中，28.9%（55/190；95%CI 22.6%至 36.0%）的患者做出了正确的猜测，大多数（61.6%，117/190）不确定。在安慰剂组中，13.0%（25/192；95%CI 8.8%至 18.8%）猜对了，大多数（69.8%，134/192）不确定。医生在泼尼松组中正确猜测的比例为 48.3%（87/180，95%CI 40.8%至 55.9%），在安慰剂组中正确猜测的比例为 66.3%（118/178，95%CI 58.8%至 73.2%），对于安慰剂组来说，这超过了机会。在泼尼松组中，医生不确定的比例为 21.7%（39/180），在安慰剂组中，医生不确定的比例为 15.2%（27/178）。预测猜测泼尼松的显著预测因素是发生高血糖症（比值比[OR]3.77，95%CI 2.39 至 5.95；p<0.001）和达到临床稳定的时间较短（OR 0.95，95%CI 0.91 至 0.99；p=0.02）。
我们证实了该研究中实现了患者盲法。医生比患者更准确地猜测。患者和医生对治疗的估计不仅受到研究药物治疗效果的预期的影响，还受到泼尼松已知副作用的影响。试验注册号：NCT00973154。
