Brief note on Randomized trails


Advances in Pharmacoepidemiology and Drug Safety is a peer-reviewed open access journal focusing on studies pertaining to rare adverse drug reactions, drug efficacy evaluations, drug interaction quantifications, patterns of drug usage, herbal medicines, randomized control trials, case control studies, cross-sectional studies, case cross over studies and cohort studies.

Brief note on Randomized trails:

A randomized controlled trial (RCT) is an experimental form of impact evaluation in which the population receiving the programme or policy intervention is chosen at random from the eligible population, and a control group is also chosen at random from the same eligible population. It tests the extent to which specific, planned impacts are being achieved. The distinguishing feature of an RCT is the random assignment of units (e.g. people, schools, villages, etc.) to the intervention or control groups. One of its strengths is that it provides a very powerful response to questions of causality, helping evaluators and programme implementers to know that what is being achieved is as a result of the intervention and not anything else.

Evidence from randomized controlled trials (RCTs) is considered to be at the top of the evidence pyramid. It is recommended that clinical practice decisions are based on evidence emanating from well-conducted RCTs when available. Following the pioneering works by James Lind for scurvy  and Sir Bradford-Hill for the treatment of tuberculosis gathering of evidence for clinical practice based on RCTs has become increasingly common. This document will review the need and scope for RCT evidence in perinatology. It will provide a practical guide to researchers wanting to pursue this exciting field of research.

Each of the eligible participants should have an equal chance to be allocated the intervention or not. The simplest way of achieving this is by parallel group design, in which each group of participants is exposed to only one of the study interventions. In a crossover design, all the trial participants receive both interventions in a sequential manner and only the order of intervention is randomly assigned. In this way, each participant serves as his/her own control, thereby eliminating individual participant differences. However, this design is more vulnerable to drop out and attrition. If a particular baseline characteristic is of such fundamental importance as to have a big influence on the outcome, it can be taken into account at randomization. Participants with or without that baseline characteristic are randomized separately (stratified randomization). Block randomization is used to maintain a balance between the intervention group and control, so that the numbers are not too dissimilar, which could rarely happen by chance. Cluster randomization can be used when randomization of individual participants is not feasible/practical, in which case hospitals, clinics, geographic areas etc. can be used as units for the allocation of intervention or control groups. Generation of random sequence should be done by some independent personnel, usually a statistician, who is not going to be involved in the conduct of the RCT. The access to this sequence should be restricted to only a few individuals who absolutely need to have access (such as the pharmacist who will be preparing the medication) and not the investigators or personnel involved in ascertaining outcome. The sequence should be opened by this individual only on a case-by-case basis and specified sequence should be followed.



Submit manuscript at or send as an e-mail attachment to the Editorial Office at