A new section of the NIH Collaboratory’s Living Textbook of Pragmatic Clinical Trials discusses challenges associated with missing data that result from noncompliance, crossover, and dropout.
Many randomized controlled trials use an intention-to-treat (ITT) analysis to measure the real-world effects of the intervention. The newly published section, Missing Data and Intention-to-Treat Analyses, considers the population-level causal effects in these trials when there is noncompliance or missing outcome data.
“One rationale for the ITT approach is that it evaluates the real-world effects of the intervention. However, a common misconception is that the ITT analysis will be unbiased regardless of crossover or missing data.”
The new section also introduces a white paper from the NIH Collaboratory’s Biostatistics and Study Design Core, “Analyses of Randomized Controlled Trials in the Presence of Noncompliance and Study Dropout.” This working document offers analysts a more detailed discussion of treatment effects in ITT analyses, including a case example and recommended strategies for estimating and reporting both ITT effects and average causal effects.
The Biostatistics and Study Design Core works with the Demonstration Project teams to create guidance and technical documents regarding study design and biostatistical issues relevant to pragmatic clinical trials.