The basic of basics correct diagnosis and patient selection

7 THE BASIC OF BASICS CORRECT DIAGNOSIS AND PATIENT SELECTION 

The reliability or precision of the diagnosis for a group of patients represents  

In this sense one can speak only about the validity and reliability of diagnoses in a population of patients. Reliability is always greater than validity. A reliable diagnosis can be invalid but an unreliable diagnosis cannot be valid. 

In clinical trials patients are selected according to a number of inclusion and exclusion criteria. Selection criteria in a clinical trial consist of  

This section deals with the question of whether there are quantitatively detectable and interpretable correlations between the dose of an administered drug, or the concentration of a drug and its metabolites measured in the blood or plasma (blood or plasma level), and the therapeutic action or side effects observed. Investigations relating to questions of this type are called PK PD (pharmacokinetic pharmacodynamic) studies. The PK PD analysis is a bidirectional approach pharmacokinetics represent what the body does with a drug, and pharmacodynamics describes what a drug does to the body. The PK PD analyses are key elements of early drug development, and PK PD trials are able to answer specific disease-related efficacy and safety questions. 

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