Clinical Trials Treatment Evaluation Criteria

By Author: Rajesh Kumar
Total Articles: 17
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Comparison of treatments in clinical research is done through the best reasoned choice but there is still a possible criterion for measuring the effectiveness and tolerance of the treatment. Ideally, these criteria are expected to be relevant, that is to say they respond to the problem, they are meaningful in clinical terms, they are subject to a consensus in the medical community, they are available in all subjects, their collection is not painful for patients, their measurement is easy, accurate, reproducible and they are sensitive i.e. able to detect small differences.


However, there are few diseases whose expression boils down to a single "master symptoms" and whose evolution cannot be measured by one criterion. In general, we must avoid multiple criteria whose number is at the origin of a multiplicity of tests making interpretation very difficult. The protocol must always focus on a criterion called "main" (used to calculate the number needed to highlight the difference expected between treatments), the others being in the hierarchy, considered only as criteria "accessories" which is not subsequently ...
... raise the question of importance, given the results. Every contract research organization follows almost the same procedure for measuring the effectiveness of the drugs or to study the research during their clinical trials services or the internal research & studies.


It is sometimes led to use of combinations - fixed a priori, with or without weighting, off criteria, which are then indices scores or numerical expression (Karnofsky scale to measure disability ...), which quantifies functional and subjective phenomena to better compare them. However, be advised that a numerical measure is not provided objective as evidenced, for example taking blood pressure even when the conditions of measurement are perfectly codified and standardized.


Conversely, some assessments cannot and must be subjective. Thus, in the case of pain, only the patient is able to express his feelings. He does this via visual analogue scales or self-assessment questionnaires taking into account all of his pain behavior (critical double-blind).


In practice, care should be taken:

Ensure that the assessment of outcome is done in the same way in both groups and for each patient.
Standardize the conditions and measurement techniques.
Educate and train observers, mainly through multi-center trials.
Specify the time of collection of the test, the same for all patients of the same group.
Imperative to evaluate the criterion in blind if the test could be conducted double blind.


Centralize the criterion measure or the list of assays especially in case of high variability or reading when it is very difficult and requires sophisticated and uncommon equipments (as is the case for some quantitative virology techniques).


If this choice of criterion of judgment or evaluation poses no particular difficulty in the context of a clinical trials services to test the effectiveness of a new drug to prevent the occurrence of an opportunistic infection, this does not even field of antiretroviral therapy. Initially, these are clinical events that were considered as evolutionary markers of infection: occurrence of opportunistic infections or life expectancy. Now the objective pursued is to replace these clinical criteria with other criteria (biological, immunological and virological above) that can be obtained much faster and are correlated with clinical outcome. These markers are referred to as a "surrogate". They allow a more rapid assessment of drug candidate and thus its availability in case of early efficacy but also its fastest drop in case of inefficiency. The validation of this type of marker is crucial in HIV infection.


In addition, particularly for chronic conditions requiring prolonged use of medication, such criteria misinform the benefit / risk ratio. The problem is even more important that the test drug is potentially toxic and the medium or long term side effects may outweigh a short-term pharmacological benefit.



There is a list of assays and validated methods in clinical research that should be better used during the evaluation of the treatment.