Blinding means more than just keeping the name of the treatment hidden. Patients may well see the treatment being given to patients in the other treatment group (s), and the appearance of the drug used in the study could give a clue to its identity.
Is it possible to blind a patient to their treatment?
In some cases, while blinding would be useful, it is impossible or unethical. For example, it is not possible to blind a patient to their treatment in a physical therapy intervention. A good clinical protocol ensures that blinding is as effective as possible within ethical and practical constraints.
What does blinding mean?
Blinding is an important tool of the scientific method, and is used in many fields of research. In some fields, such as medicine, it is considered essential. In clinical research, a trial that is not a blinded trial is called an open trial .
What is blindness and how can it be treated?
According to the National Eye Institute, the U.S. defines blindness as having a visual acuity of 20/200 or less, with the best vision correction in the better-seeing eye.
What does it mean to be blind in a clinical trial?
Blinding in clinical trials and other studies. Blinding means more than just keeping the name of the treatment hidden. Patients may well see the treatment being given to patients in the other treatment group (s), and the appearance of the drug used in the study could give a clue to its identity.
What does blinding a patient mean?
Unblinding, sometimes referred to as code-break, is the process by which the treatment/allocation details are made available either purposefully (i.e according to the code-break procedures) or accidently.
What is blinding in healthcare?
Blinding refers to the concealment of group allocation from one or more individuals involved in a clinical research study, most commonly a randomized controlled trial (RCT).
Who should be blinded in a clinical trial?
All of the different parties involved in a clinical trial are possible sources of bias and can be blinded to ensure trial objectivity, including: The patient being treated. The clinical staff administering the treatment. The physician assessing the treatment.
What is a blinding procedure?
Blinding means concealing the treatment allocation from patients and any other people involved in the trial who may bias the results of the trial by knowing which groups the patients were randomised to. Blinding of patients prevents reporting bias in patient-reported measures.
What does blinded mean in clinical trials?
Listen to pronunciation. (BLINE-ded STUH-dee) A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given.
What is the purpose of blinding in clinical trials?
Blinding (sometimes called masking) is used to try to eliminate such bias. It is a tenet of randomised controlled trials that the treatment allocation for each patient is not revealed until the patient has irrevocably been entered into the trial, to avoid selection bias.
What is blinded assessment?
Blind outcome assessment refers to the process of concealing treatment group identity from outcome assessors, after their treatment assignment through randomization, to minimize the occurrence of biased assessments influencing research findings.
What is the difference between masking and blinding in clinical trials?
In addition, masking is sometimes used to describe how treatments are made indistinguishable [18, 19, 25, 26], whereas blinding usually indicates which groups are unaware of treatment assignment [1,2,3,4,5,6].
What is blinding and unblinding in clinical trials?
But what exactly is a double-blind clinical trial? And who is blinded in a single-blind study? Naturally, the types of blinded studies depend on the number of parties blinded. If everyone is aware of who gets what kind of treatment, the study is called unblinded or open label.
What does lack of blinding mean?
The lack of concealment of an intervention or control treatment received by participants in a clinical trial.
What does blinded data mean?
Blinding, in research, refers to a practice where study participants are prevented from knowing certain information that may somehow influence them—thereby tainting the results.
What does it mean when you are completely blind?
A completely blind individual is unable to see at all . The word blindness, however, is commonly used as a relative term to signify visual impairment, or low vision, meaning that even with eyeglasses, contact lenses, medicine or surgery, a person does not see well. Vision impairment can range from mild to severe.
What is temporary blindness?
Temporary blindness differs in causes from permanent blindness. The diagnosis of blindness is made by examination of all parts of the eye by an ophthalmologist. The universal symptom of blindness or visual impairment is difficulty with seeing.
How can blindness be prevented?
Most traumatic causes of blindness can be prevented through eye protection. Nutritional causes of blindness are preventable through proper diet. Most cases of blindness from glaucoma are preventable through early detection and appropriate treatment.
Why do I get snow blind?
Snow blindness is usually temporary and is due to swelling of cells of the corneal surface. Even in the most severe cases of snow blindness, the individual is still able to see shapes and movement. People often say, "I am 'blind as a bat' without my glasses.".
Why are people blind in third world countries?
In third-world nations where many people have poor vision as a result of a refractive error, merely prescribing and giving glasses will alleviate the problem. Nutritional causes of blindness can be addressed by dietary changes. There are millions of people in the world who are blind from cataracts.
What causes blindness in older people?
Common causes of blindness include diabetes, macular degeneration, traumatic injuries, infections of the cornea or retina, glaucoma, and inability to obtain any glasses.
How many people are blind in the world?
Worldwide, between 300 million-400 million people are visually impaired due to various causes. Of this group, approximately 50 million people are totally blind. Approximately 80% of blindness occurs in people over 50 years of age.
What is the most common method of blinding in RCTs?
One of the most common methods of blinding in RCTs is the use of seemingly identical medications; one ‘active’ pill and one ‘placebo’ pill. As they are physically identical, it is impossible for patients and researchers to discern which pill is the active one based on appearance alone.
Can a surgeon be blinded?
However, it can be difficult to blind the surgeon to the tested intervention as they must perform the procedure. This still remains a challenge in medical research. (Although it is not impossible to blind surgeons: have a look at this for more information).
Is blinding possible?
In cases where blinding is not possible or feasible, the outcome measures must be objective! If you are reading a study that is un-blinded, with subjective outcome measures, then you may as well stop reading it and move on.
Should blinding be attempted in other areas of the study?
It is recommended that the groups are treated as equally as possible, blinding should be attempted in other areas of the study and that any lack of blinding should be recognised in the limitations section [8].
Should RCTs be double blind?
Where possible, RCTs should be at least double-blinded, and should have more blinding where possible (this includes: patients, clinicians/researchers, data collectors and statisticians) Where blinding is not feasible, this should be recognised as a limitation and blinding should be attempted in other areas of the trial.
What is blinding in a trial?
It is a tenet of randomised controlled trials that the treatment allocation for each patient is not revealed until the patient has irrevocably been entered into the trial, to avoid selection bias.
Why is blinding important in epidemiology?
Blinding is important in other types of research too. For example, in studies to evaluate the performance of a diagnostic test those perform ing the test must be unaware of the true diagnosis.
What is double blinding in clinical trials?
In controlled trials the term blinding, and in particular “double blind,” usually refers to keeping study participants, those involved with their management, and those collecting and analysing clinical data unaware of the assigned treatment, so that they should not be influenced by that knowledge.
Can patients see the treatment being given to patients in the other treatment group?
Patients may well see the treatment being given to patients in the other treatment group (s), and the appearance of the drug used in the study could give a clue to its identity. Differences in taste, smell, or mode of delivery may also influence efficacy, so these aspects should be identical for each treatment group.
Is blinding always possible?
Blinding is certainly not always easy or possible. Single blind trials (where either only the investigator or only the patient is blind to the allocation) are sometimes unavoidable, as are open (non-blind) trials. In trials of different styles of patient management, surgical procedures, or alternative therapies, full blinding is often impossible.
Why do we use blinding in clinical trials?
Blinding is used in Clinical Trials to remove any bias that can be caused intentionally or unintentionally if participants or the research team are aware of who is receiving an active or placebo treatment. For example, in a blinded trial that has a group of subjects receiving the treatment being tested and a group of subjects receiving ...
What is blind trial?
A blind trial is the opposite of an open, open-label, or un-blinded trial where all parties are aware of the treatment the participant receives. All of the different parties involved in a clinical trial are possible sources of bias and can be blinded to ensure trial objectivity, including: The clinical staff administering the treatment.
When is data blinding done?
The data blinding process can occur either at the end of a study or during it. Undertaking data blinding during a trial enables Sponsors/CROs to identify any potential biases in their data gathering processes, which can then be rectified early on, saving considerable time and money, and enabling the trial to meet its endpoints.
Why is data blinding important?
Data blinding is particularly useful when you have multiple clinicians collecting data and/or multiple sites gathering data because of the increased number of variables that could cause biases in the data. The data blinding process can occur either at the end of a study or during it.
What are the criteria to be legally blind?
To be considered legally blind, you would have to meet one of two criteria for visual acuity (sharpness of vision) and visual field (the entire scope of what you can see without moving your eyes).
What causes legal blindness?
Age-related eye diseases that are the leading causes of low vision and blindness are: 6 . Eye trauma or injuries and genetic conditions, such as Usher syndrome, can also lead to legal blindness.
What is low vision?
Low vision is a visual acuity of 20/40 or worse while wearing corrective lenses. More than 4.2 million people over age 40 are legally blind or have low vision, according to the Centers for Disease Control and Prevention. 6 . Visual Acuity Testing.
How to treat glaucoma?
For example, the goal of treatment for glaucoma is to reduce eye pressure. This can be achieved with prescription eye drops or oral medications, laser procedures, and, in severe cases, surgeries to try to prevent further damage.
Can you get a driver's license if you are blind?
2 For safely reasons, people with legal blindness or low vision typically are not eligible for a driver's license.
What is legal blindness?
Legally blind is used by the government to describe a person with vision below a certain measurement. According to the National Eye Institute, the U.S. defines blindness as having a visual acuity of 20/200 or less, with the best vision correction in the better-seeing eye. Visual acuity refers to the clarity of a person’s vision.
What is the difference between being blind and being partially blind?
A person who is completely blind is unable to see anything, while a person who is partially blind or has a visual impairment may have limited vision. people in the United States were legally blind, while 3.2 million had some form of visual impairment. In some cases, a person is born blind.
What is the visual field of a person with severe visual impairment?
Severe visual impairment. A person who has a severe visual impairment will have a Snellen visual acuity of 20/200 to 20/400. Alternatively, an eye doctor may regard someone as having a severe visual impairment if they have a visual field of 20 degrees or less. The visual field is the area a person can see without moving their eyes to ...
How far can a blind person see?
This means that a person with 20/20 vision can see what an average person sees when standing 20 feet away from an object. However, legally blind people will have a Snellen visual acuity of 20/200, meaning that at 20 feet, they can see objects that most people are able to see clearly from 200 feet.
What causes blindness in the eye?
Some causes of blindness or visual impairment that do have available treatments include: 1 Diabetic retinopathy: If the cause of visual impairment is diabetic retinopathy, treatment may help stop it from worsening. However, it cannot cure any existing damage. This treatment may involve receiving injections into the eye, trying laser treatment, or undergoing eye surgery. 2 AMD: There are two types of AMD: dry and wet. If a person has dry AMD, there is no available treatment. However, if a person has wet AMD, treatments may consist of regular injections or a treatment called photodynamic therapy. 3 Cataracts: Cataracts cause the lens of the eye to become cloudy, which may affect vision. A person with severe cataracts may require surgery to save their vision.
What is visual acuity?
Visual acuity refers to the clarity of a person’s vision. To test a person’s visual acuity, an eye care professional may ask them to read letters on a Snellen chart. The Snellen chart contains several lines of letters that start large and get smaller with each line.
Why do people become blind?
In other cases, a person becomes blind or develops a visual impairment due to a condition, eye trauma, factors relating to aging, or cataracts. This article will define blindness and visual impairments, discuss different types of visual impairment, and see which government benefits and treatment options are available.
Why is blinding important?
In some fields, such as medicine, it is considered essential. In clinical research, a trial that is not a blinded trial is called an open trial .
What is a blinded experiment?
Experiment in which information about the test is masked to reduce bias. In a blind or blinded experiment, information which may influence the participants of the experiment is withheld (masked or blinded) until after the experiment is complete. Good blinding can reduce or eliminate experimental biases that arise from a participants' expectations, ...
What is unblinding in pharmacology?
Unblinding is common in blinded experiments , particularly in pharmacological trials. In particular, trials on pain medication and antidepressants are poorly blinded. Unblinding that occurs before the conclusion of a study is a source of experimental error, as the bias that was eliminated by blinding is re-introduced.
Why is unblinding a common cause?
A common cause for unblinding is the presence of side effects (or effects) in the treatment group. In pharmacological trials, premature unblinding can be reduced with the use of an active placebo, which conceals treatment allocation by ensuring the presence of side effects in both groups.
When does unblinding occur?
Unblinding occurs in a blinded experiment when information becomes available to one from whom it has been masked. In clinical studies, unblinding may occur unintentionally when a patient deduces their treatment group. Unblinding that occurs before the conclusion of an experiment is a source of bias.
Why do symphony orchestras have blind tests?
Blind tests can also be used to compare the quality of musical instruments.
How many blinded trials are there for acupuncture?
While the possibility of blinded trials on acupuncture is controversial, a 2003 review of 47 randomized controlled trials found no fewer than four methods of blinding patients to acupuncture treatment: 1) superficial needling of true acupuncture points, 2) use of acupuncture points which are not indicated for the condition being treated, 3) insertion of needles outside of true acupuncture points, and 4) the use of placebo needles which are designed not to penetrate the skin. The authors concluded that there was "no clear association between type of sham intervention used and the results of the trials."
What Is Blinding?
Common Methods of Blinding
- One of the most common methods of blinding in RCTs is the use of seemingly identical medications; one ‘active’ pill and one ‘placebo’ pill. As they are physically identical, it is impossible for patients and researchers to discern which pill is the active one based on appearance alone. This is an example of robust blinding. If it is not robust, there is a risk of un-blinding. This is dem…
Why Is Blinding Important?
- Blinding is important for the validity of RCTs. Without it there are number of biases that are unwillingly introduced.It has been shown in an assessment of 33 meta-analyses, encompassing 250 RCTs, that without blinding, odds ratios were exaggerated by up to 17% (P=0.01). This highlights the importance of not just reading medical literature, but appraising it with a critical le…
What About When Blinding Is Not Possible?
- In cases where blinding is not possible or feasible, the outcome measures must be objective!If you are reading a study that is un-blinded, with subjective outcome measures, then you may as well stop reading it and move on. This is because, if a patient is aware they are receiving the active intervention and the outcome measure is subjective, such as ‘how much pain they are exp…
Allocation Concealment
- Allocation concealment is ensuring that the person(s) randomising participants does not know what the next treatment allocation must be. This is an often underappreciated aspect of many trials that may lead to significant selection bias and invalid conclusions if not implemented[6,7]. CONSORT guidelines recommend that all RCTs have a robust method of randomisation to ensur…
Summary
- Blinding is an important foundation for ensuring internal validity and reducing observer bias
- Blinding must be robust and methods of blinding should be reported in detail
- Where possible, RCTs should be at least double-blinded, and should have more blinding where possible (this includes: patients, clinicians/researchers, data collectors and statisticians)
- Where blinding is not feasible, this should be recognised as a limitation and blinding should b…
- Blinding is an important foundation for ensuring internal validity and reducing observer bias
- Blinding must be robust and methods of blinding should be reported in detail
- Where possible, RCTs should be at least double-blinded, and should have more blinding where possible (this includes: patients, clinicians/researchers, data collectors and statisticians)
- Where blinding is not feasible, this should be recognised as a limitation and blinding should be attempted in other areas of the trial
