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Introduction to Clinical Trial Research Paper

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Updated: Nov 29th, 2019


Studies show that human behaviors are subjective to whatever each one believes or knows. In fact, in most studies the expectations tend to present certain degrees of risks that influence the research outcomes. The expectations seem to occur particularly whenever the assessments show some level of subjectivity. The resultant effect is the generation of biased findings.

Thus, researchers in clinical trials tend to use masking also dubbed as blinding in order to get rid of the biasness. However, many clinical researchers across the globe seem to comprehend the term blinding although there are perplexities lurking afar the general understanding of the term. For instance, the types of blinding namely triple blinding, double blinding, and single blinding have different meanings according to various individuals. The different views create miscomprehensions resulting from the confusing meanings.

In clinical trials, blinding has a very rich account that has been in existence for centuries. According to medical literature, blinding entails making all the data collectors (assessors), healthcare providers (investigators) and trial participants uninformed about the allocated intervention in order to avoid the influence of such information.

Besides improving the trial participants’ retention and conformity, blinding minimizes knowledge bias also called the differential evaluation of results. This research examines the importance of blinding in clinical trials, the types of blinds, as well as offers recommendation on the best type of blind.

The importance of blinding in clinical trials

Blinding plays an invaluable role as a methodological aspect of the randomized controlled trials in clinical research studies. In other words, blinding provides the most favorable devices for minimizing the probability of disparity in treatment as well as the evaluation of outcomes in clinical trials. Besides, the cover up of group allocation from a number of individuals involved in clinical studies comes with its own justifications and significance (Devereaux, Manns, & Ghali, 2001).

When randomized controlled trials are conducted well and thoroughly, the ingredients for the provision of optimal approximations arise from the effect of the intrusions involving surgeries. In addition, masking has a strong point in augmenting the validity of statistical experiments applied in the justification process. This arises founded on the fact that the disparities incurred in the intervention groups and control groups portray the differences between two random samples of the population.

In essence, the disparities amid the control and interference study groups ought to be evaluated against the likelihood expectations in the research populace (Kaptchuk, 1998). Numerical experiments are based on various presuppositions ranging from adequate test sizes to the standard variation allocations that are autonomous from blinding as a fraction of the study plan.

Secondly, blinding in clinical trials produces a cluster of attributes that are similar considering the known and unknown aspects of prognosis. For instance, through the generation of two factions of focus that have comparable attributes, blinding appears to be important in reducing the predisposition arising from the event where a single group of the sample has attributes that are either recognized or indefinite. The attributes must be influencing the connection that exists between the intervention and the expected results.

Third, through blinding in clinical trials, there is the elimination and minimization of the remaining prejudices to the least levels. For instance, predispositions can take place at different levels during clinical trials.

In fact, the period of the prospective evaluation where the healthcare providers, investigators, and screening teams such as data safety monitoring boards are blinded as the subjects’ consigned cluster. At this point, the healthcare providers’ comprehension has the effect of influencing the clinical care of the subjects thereby leading to bias (Kaptchuk, 1998). Additionally, during the assessment of the results as well as judgment deliverance, the evaluators of the results are masked in order to be invisible to the subjects of the assigned group.

In the event where the outcome assessors are unmasked involving the board responsible for making the final judgment on the accomplishment of the clinical trial, the evaluators may be biased due to their preconceived expected result perceptions.

Moreover, during the actual assignment that precedes masking the group in focus to their assigned cluster, the unmasked subjects are capable of changing their individual actions and the autonomous evaluations relating to the qualities of life, which are key endpoints in clinical trials.

Generally, failure of the subjects to comprehend clearly their assigned groups would bring the likelihood of them crossing from the control group to the intervention cluster (Sackett, 2007). Similarly, the blinded subjects portray less likelihood of being eliminated from the study.

Blinding in clinical trials also has ethical importance. In fact, masking subsequent to clinical trial ensures that all subjects are provided with equal opportunities during the trial. In essence, clear and proper randomization in allocating the subjects to the intervention or control cluster is irrespective of any predisposition of the conceived intentions.

Blinding is also important in preventing the subsequent assignments in clinical trial from being recognized. Thus, blinding enables healthcare providers to be unable to know the next group of patients that are to be allocated prior to entering the trial. For instance, a doctor administering a new drug intended to help patients lose their body weights is required to randomize the subjects to the new weight-losing drug.

If the doctor knows the drug that is to be administered to the next patient, the possibility of the doctor inclining to the patients is perceived to benefit more from the administration of the drug. Based on this development, blinding is very important in the elimination of the predetermined awareness of upcoming cleaning trial assignments (Sackett, 2007). The absence of concealment leads to overestimation of the intervention consequences.

Studies indicate that the utilization of inadequate allocation blinding during clinical trials produces up to over forty percent treatment effect compared to trials conducted using adequate allocation concealment thereby leading to biasness.

For instance, considering a trial of glucosamine in the treatment of knee pain, forty-eight patients underwent randomization for either placebo (n=23) or glucosamine (n=25). Through the employment of blinding experimental design, the results indicated that approximately ninety percent of the patients in the glucosamine cluster recorded improvement in the knee pain (Kaptchuk, 1998).

Conversely, approximately twenty percent of those in the placebo group recorded improvement in knee pain. Based on the results, it is evident that the application of adequate concealment in clinical trial gives standardized treatment effects. Moreover, blinding during clinical trials makes sure that the concealment schemes are unknown using adequate blinding techniques. For instance, the use of sequentially numbered, opaque, and sealed envelopes is an example of blinding technique thereby assuring adequate concealment.

Types of blinds

Even though the term blinding brings difficulty and confusion in understanding, a number of pollsters throughout the globe today comprehend it better than they used to do in the past. In fact, the researchers have mystified blinding with the allotment concealment due to misapprehension. According to the different opinions and understanding of the diverse groups of people, there are three types of blinding (Schulz, Chalmers, & Altman, 2002).

The types of blinding include triple blinding, double blinding, and single blinding. In all the blinding cases, the assessors, investigators in the trial, and participants are blocked from the familiarity with the investigation assignment. All these types are opposed to an open label or non-blinded clinical trials where the recipient of the intervention becomes identified using everybody in the trial process.

When all through the entire process of trial a single party out of the three groups of characters in the trial remains unaware of the intervention project, the clinical trial is dubbed as single blinding. However, bewilderment when defining single blinding may occur given that the assessor lacks familiarity with the intervention, but the examiner and the participants are aware of such interventions. Conversely, some differences emerge in the case of double binding trial (Juni, Altman, & Egger, 2001).

For instance, during the whole process of double blinding trial, the evaluator, examiner, and the participants are all not in possession of the facts of the intervention mission. As such, the researchers are at times hoodwinks in that the whole group is kept unaware of the intervention assignment. Interestingly, double blinding might precisely refer to the two classes in that the examiner as well as the regular assessments in the case of medicinal investigation.

In contrast, triple blinding trail denotes a double blind trial where the unsighted data analysis is sustained. The examiners may observe the experiment as triple blinding when the participants, researchers, and evaluators are all uninformed of the intervention mission. In addition, the examiners perceive an experiment as a triple blind once the evaluators and examiners are both distinct and ignorant of the involvements.

The triple bind is not often employed by the examiners to mean blinding of information analysts, evaluators, and contributors (Sackett, 2007). Therefore, all the three categories of individuals in triple blinding clinical trials are scheduled to have no any other information about the involvement tasks.

The best type of blind and why

In view of all the three types of blinding, I would prefer the double blinding to the triple and single blinding during clinical trials. Indeed, several researchers and medical investigators insist on a double blinding clinical trial as it is of high quality.

For instance, in this type of blinding, failures hardly appear during the blinding process. In fact, all trial participants are very unaware of the preceding and upcoming trails events. That is, everyone lacks knowledge on what the clinical results would be after the trial is completed. Although double blinding is of high quality, it may not offer the most important general quality of the trial.

There is an indication of blinding the outcome assessors, participants, and investigators, which might lead to death. However, since double blinding is a sin qua non of the randomized control trial, it prevents biasness. As examined in the practical studies, double blind trial avoids bias to some extents while on regular grounds it puts a stop to biasness than sufficient concealment.


In randomized control clinical trials, the outcome validity can be maximized through blinding technique, which assists researchers in minimizing information bias. Based on the research analysis, the clinical trial participants including data analysts, result judges, data gatherers as well as practitioners ought to be blinded.

However, despite the presence of different kinds of blinding, very few clinical trials tend to include blinding during research studies. Blinding can only be achieved via the use of inventive and novel methods. Irrespective of the limitations eminent in triple blinding, double blinding, and single blinding, double blinding appears to be the best type of blinding. In this type of blinding, failures hardly appear during the blinding process.


Devereaux, P., Manns, B., & Ghali, W. (2001). Physician interpretations and textbook definitions of blinding terminology in randomized controlled trials. JAMA, 285 (3), 2000–03.

Juni, P., Altman, D., & Egger, M. (2001). Systematic reviews in health care: assessing the quality of controlled clinical trials. BMJ, 323 (6), 42–6.

Kaptchuk, T. (1998). Intentional ignorance: A history of blind assessment and placebo controls in medicine. Bull Hist Med, 72(2), 389–433.

Sackett, D. (2007). Measuring the success of blinding in RCTs: Don’t, must, can’t or needn’t. Int J Epidemiol, 36(3),664–5.

Schulz, K., Chalmers, I., & Altman, D. (2002). The landscape and lexicon of blinding in randomized trials. Ann Intern Med, 136 (1), 254–59.

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