Section: New Results

Multivariate Analysis for the detection of the effect of a treatment

Participant : Anne Gégout-Petit.

The aim of this work is to give some statistical rules to determine if a patient is meeting a given treatment (a BD here). The criterium commonly used to determine if a patient is meeting a BD treatment is based only on one physiological parameter : if this parameter increases, the patient is meeting. But now, many physiological parameters are measured in routine and physiologists '"ont le sentiment" that a patient could have a global amelioration of his health state due to the treatment without an increase of the single used parameter.

Using the measures of six variables before and after the treatment, the expected value of this variable under the hypothesis of good health, we first propose indices of amelioration. Using standard multivariate analysis techniques, we first study the correlation between these indices. We use classification in order to constitute groups of patients whose present homogeneous treatment responses. The method used on a cohort of 100 subjects gives three groups : in the first one, the mean of the indices is near zero, the treatment has no effect. In the second one, subjects present significant amelioration regarding two of the indices but not the indices related to the commonly used one. The last group show an amelioration for all the indices.

We have proposed criteria to discriminate the three groups. These criteria where used on a validation cohort to constitute three groups. Their global characteristics were the same as in the original cohort and it comforts the validity of the method. This work will be used by physiologists to propose new criteria for the measure of the effect of a BD treatment. It is in collaboration with physiologists from Bordeaux and Nantes universities and is the object of a paper that will be soon submitted in a international peer-reviewed journal in the domain of pneumology.