RCT Principles

A 42-year-old woman with type 2 diabetes mellitus is enrolled in a randomized controlled trial comparing a new SGLT2 inhibitor versus metformin for glycemic control over 12 weeks. The trial protocol specifies that participants will be stratified by baseline HbA1c (≤8% vs >8%) and randomized 1:1 to each arm using computer-generated random number tables. After randomization, 5 participants in the SGLT2 inhibitor arm develop genital mycotic infections and withdraw. The metformin arm reports no withdrawals. The principal investigator decides to replace these 5 participants with new recruits to maintain equal group sizes. What is the primary methodological flaw introduced by this post-randomization replacement strategy?

A pharmaceutical company is designing a Phase III randomized controlled trial (RCT) to evaluate the efficacy of a new antihypertensive drug in Indian adults aged 40–65 years with stage 2 hypertension. The trial protocol specifies a 1:1 allocation ratio, but the biostatistician raises concern about baseline imbalance in a key prognostic variable (left ventricular hypertrophy, LVH) between the two arms after randomization. What is the most appropriate next step to minimize this risk in future recruitment?

A researcher is designing a randomized controlled trial to evaluate the efficacy of a new antihypertensive drug in Indian adults. To detect a clinically meaningful difference of 5 mmHg in systolic blood pressure between the intervention and control groups with 80% power and a two-tailed alpha of 0.05, which investigation/calculation is the most appropriate FIRST step?

In the design of randomized controlled trials, what is the most common method of randomization used in practice?

Which is the most common reason for loss to follow-up in randomized controlled trials conducted in India?