Clinically relevant difference concept

Power. The power is the probability of concluding that the alternative hypothesis is true given that it is in fact true. It depends on the statistical test being employed, the size of that test, the nature and variability of the observations obtained and the size of the trial. It also depends on the alternative hypothesis. In practice there is no single alternative h3fpothesis, so a reference alternative based on a clinically relevant difference is usually employed. The power of a trial is a useful concept when planning the trial but has little relevance to the interpretation of its results. (Caution not all statisticians agree with this last statement.)... 

Both the inhaled and the intravenous anesthetics can depress spontaneous and evoked activity of neurons in many regions of the brain. Older concepts of the mechanism of anesthesia evoked nonspecific interactions of these agents with the lipid matrix of the nerve membrane (the so-called Meyer-Overton principle)—interactions that were thought to lead to secondary changes in ion flux. More recently, evidence has accumulated suggesting that the modification of ion currents by anesthetics results from more direct interactions with specific nerve membrane components. The ionic mechanisms involved for different anesthetics may vary, but at clinically relevant concentrations they appear to involve interactions with members of the ligand-gated ion channel family. 

The clinical relevance of L/T ratio, a theoretical concept, is, however, less clear. Indeed, the L/T ratio is useful only in comparing the same drug substance in different inhaler devices. Comparisons between drugs should not be made, as different substances may differ in terms of relative activities in lungs and systemic circulation. For example, inhaled glucocorticosteroids, such as fluticasone, with minimal GI bioavailabiUty and hence a very high I/T ratio, have been shown to exert systemic effects (51). The L/T ratio should thus always be verified clini-... 

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