Glossary of Clinical Research - B

B

• Baseline

• 1. Information gathered at the beginning of a study from which variations found in the study are measured. 2. A known value or quantity with which an unknown is compared when measured or assessed. 3. The initial time point in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested. At this reference point, measurable values such as CD4 count are recorded. Safety and efficacy of a drug are often determined by monitoring changes from the baseline values. (NLM)
• An initial measurement that is taken at an early time point to represent a beginning condition, and is used for comparison over time to look for changes. For example, the size of a tumor will be measured before treatment (baseline) and then afterwards to see if the treatment had an effect. (NCI)

• Bayesian approaches

Approaches to data analysis that provide a posterior probability distribution for some parameter (e.g. treatment effect), derived from the observed data and a prior probability distribution for the parameter. The posterior distribution is then used as the basis for statistical inference. (ICH E9)

• Best practice

In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with the best practice. Also called standard therapy or standard of care. (NCI)

• Bias

• In a scientific research study or clinical trial, a flaw in the study design or the method of collecting or interpreting information. Biases can lead to incorrect conclusions about what the study or clinical trial showed. (NCI)
• When a point of view prevents impartial judgment on issues relating to the subject of that point of view. In clinical studies, bias is controlled by blinding and randomization (NLM)
• The systematic tendency of any factors associated with the design, conduct, analysis and evaluation of the results of a clinical trial to make the estimate of a treatment effect deviate from its true value. Bias introduced through deviations in conduct is referred to as 'operational' bias. The other sources of bias listed above are referred to as 'statistical'. (ICH E9)

• Bioavailable

The ability of a drug or other substance to be absorbed and used by the body. Orally bioavailable means that a drug or other substance that is taken by mouth can be absorbed and used by the body. (NCI)

• Bioinformatics

The science of using computers, databases, and math to organize and analyze large amounts of biological, medical, and health information. Information may come from many sources, including patient statistics, tissue specimens, genetics research, and clinical trials. (NCI)

• Biological drug

A substance that is made from a living organism or its products and is used in the prevention, diagnosis, or treatment diseases. Biological drugs include antibodies, interleukins, and vaccines. Also called biologic agent or biological agent. (NCI)

• Biometrics

The science of collecting and analyzing biologic or health data using statistical methods. Biometrics may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometry. (NCI)

• Biometry

The science of collecting and analyzing biologic or health data using statistical methods. Biometry may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometrics. (NCI)

• Biostatistics

The science of collecting and analyzing biologic or health data using statistical methods. Biostatistics may be used to help learn the possible causes of a disease in a certain group of people. Also called biometry and biometrics. (NCI)

• Blind

• A randomized trial is "Blind" if the participant is not told which arm of the trial he is on. A clinical trial is "Blind" if participants are unaware on whether they are in the experimental or control arm of the study; also called masked. (NLM)
• A procedure in which one or more parties to the trial are kept unaware of the treatment assignment(s). Single blinding usually refers to the subject(s) being unaware, and double blinding usually refers to the subject(s), investigator(s), monitor, and, in some cases, data analyst(s) being unaware of the treatment assignment(s). (ICH E6)

• Blind review

The checking and assessment of data during the period of time between trial completion (the last observation on the last subject) and the breaking of the blind, for the purpose of finalising the planned analysis. (ICH E9)

• Blinded study

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. The opposite of a blinded study is an open label study. (NCI)