Epidemiological Survey of Functional
Symptomatology in Preschool-Age Children
Françoise Davidson, M.D.
Marie Choquet, Ph.D.
The epidemiologist has two types of overall approach to functional pathology in the infant. The first and most common method consists of defining a group of children with various clinical symptoms within a sufficiently large infant population. In such a case the epidemiologist draws on the experience of physicians to determine significant symptoms and to define a high-risk group on the basis of these criteria. Comparison of this group with a control group composed of children who do not have these characteristics enables the epidemiologist to isolate differences from various possible points of view (family history, type of upbringing, type of day care, and so forth).
The other method, described here, consists of using appropriate statistical methods to establish "classes" of subjects within an unselected population of children. The classes or groups established in this manner should be as uniform as possible with respect to the overall data under study and should be established without recourse to any prior assumptions. At the same time, these groups must be as different as possible from one another. This system of classification will reveal both the most sig‐
nificant factors and their relationships, thereby providing a profile for each group.
By comparing the various groups established on this basis, the epidemiologist can describe them from various points of view (socioeconomic level, parents' state of health, and the like), follow them up, and validate the methods used.
LONGITUDINAL STUDY OF SAMPLE
The sample studied was composed of 415 children from the 14th District of Paris. They were studied from age three months to three years at four important moments in their lives (three months, nine months, eighteen months, and three years).
At each step, a questionnaire concerning the child (physical, psychological, and emotional development, type of day care, parents, and living conditions) was filled out by an experienced psychologist during an interview with the mother. Each interview lasted approximately one hour. No systematic observa____________________