What is ‘Blinding’ in Research? What are Its Types?

May 25, 2020 Kusum Wagle Epidemiology 0

What is Blinding in Research?

  • Blinding, in research, mentions to a practice where the study population or the stakeholders involved in research are not permitted from knowing certain information or treatment, which may somehow influence the study findings.
  • Blinding refers to covering up of certain information from one or more research participants in a clinical research study, most commonly a Randomized Controlled Trial (RCT) to reduce bias.
  • Blinding is mainly carried out while conducting RCTs.

Use of Blinding in Research:

  • Minimizes bias and maximizes validity of the results.
  • Improves the reliability of clinical research results.
  • Prevents conscious or unconscious bias in the design and during execution of a clinical trial.
  • Allows investigators to control the exposure levels as needed.
  • Gives an honest research findings.
  • Allows a realistic statistical comparison.
  • Helps to ensure unbiased ascertainment of outcomes.

Different Types of Blinding:

There are basically three different types of blinding used in researches:

1. Single blinding or single-masked:

  • In single blinding, only a single stakeholder i.e. either the participant or the investigator is not informed of the nature of treatment the participant is receiving.
  • A trial is called single-blind if only one party is blinded. Usually, the participant is blinded and is unaware of the treatment they receive.

2. Double-blinding or double-masked:

  • Double-blinded study is defined as a study, in which both study population/participant and data collectors/investigators/researchers are not aware of the kind or nature of the treatment given and who receive the treatment.
  • If both ‘the participants’ and ‘the study staffs’ are blinded, it is known as a double- blind study.

3. Triple blinding:

  • A clinical trial or experiment in which neither the subject nor the person governing treatment nor an individual measuring the response to the treatment is aware of the particular treatment received by the subject is known as triple blind. Triple blinded studies also lengthen blinding to the data specialists.
  • In triple blinding, the study participant, the data investigator or data collector and the data analyzer- all are blinded.
  • Only the Principle Investigator of the research might know about the trial– may it be treatment, drugs or so on.

4. Unblinded or open-label:

  • It is the exact opposite of blinding, where all the participant, clinicians, data collectors, specialists are well known about the treatment/intervention they receive.

Advantages & Limitations of Different Types of Blinding:

Different types of blinding Advantages Limitations
Single blind

 
  • Such studies help to control the bias where the results might be affected/distorted by participants’ knowledge or identification of the materials they are assessing.
  • Sounds more unethical to study participants who are not informed or known about the treatment they are receiving.
Double blind

 
  • It prevents research outcomes from being ‘biased’ and not influenced by knowledge of the participant and the researcher.
  • It is a basic tool to prevent conscious and unconscious bias in research.
  • It avoids deception in the research process
  • Lack of adequate demographic controls.
  • It doesn’t reflect real-life circumstances
  • It is complex and not always possible to complete study by applying double blinding

 
Triple blind

 
  • It extends binding to the data analysts.
  • The objective of triple-blinding process is to control possible bias from study participants, researchers and data analysts to maximize accuracy and objectivity of clinical outcomes.
  • It is complex and not applicable for a larger study population.
  • Often difficult to blind all three parties
Unblinded or open level

 
  • Unblinding a trial is a necessary process to safeguard participants in the event of medical or safety reasons.
  • The process of unblinding is planned and included in the study protocol.
  • Potential lower efficiency
  • Chances of bias and error in results

Limitations of Blinding:

  • More costly in time and money.
  • Standardized interventions may be different from common practice.
  • Many research questions are not suitable for blinding.
  • Only applicable for some research questions.

References and For More Information:

https://www.medicinenet.com/parkinsons_disease_clinical_trials/article.htm

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2947122/

https://www.iwh.on.ca/what-researchers-mean-by/blinding

Skin – Half Width

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181999/

16 Advantages and Disadvantages of a Double-Blind Study

http://i-base.info/ttfa/8-clinical-trials-and-research/8-7-randomised-double-blind-placebo-controlled-trials/

https://www.sciencedaily.com/terms/double_blind.htm

https://jamanetwork.com/journals/jama/article-abstract/187750

https://medical-dictionary.thefreedictionary.com/triple+blind

https://www.exordo.com/blog/single-blind-peer-review/

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1538-7836.2008.02848.x

https://methods.sagepub.com/Reference//encyc-of-research-design/n471.xml

About Kusum Wagle 214 Articles
Hello and greetings everyone! I am Kusum Wagle, MPH, WHO-TDR Scholar, BRAC James P. Grant School of Public Health, Bangladesh. I have gained profound experiences in public health sector under different thematic areas of health, nutrition, sexual and reproductive health, maternal and newborn health, research etc., targeting diverse audience of different age groups. I have performed diverse roles ranging from lecturer in the public health department of colleges, nutrition coordinator, research coordinator and consultant, in different programs, projects and academic institutions of Nepal. I also hold immense experience in working closely and persistently with government organizations, non-government organizations, UN agencies, CSOs and other stakeholders at the national and sub-national level. I have successfully led and coordinated different projects involving multi-sector participation and engagement. Moreover, I am also regularly involved in the development of different national health related programs and its guidelines.