Biomedical pattern discrimination of neonatal cardiovascular risk.

Genetic risk is a primary contributing factor to the predisposition of a newborn child to elevated blood pressure later in life. An index for this factor is needed to assess in the neonate the success or failure of preventive interventions instituted for the pregnant woman. This index could be based on characteristics describing the variability of blood pressure and heart rate during the first days after birth. In the search for such an index, the systolic and diastolic blood pressures and heart rates of 150 newborn babies were automatically monitored at about 30-minute intervals for 48h with a Nippon Colin device, starting early after birth. On the basis of questionnaires given to the parents, the neonates were assigned to a group of either a negative or positive family history of high blood pressure, according to the absence or presence of high blood pressure and/or related cardiovascular disease in two generations (those of the newborn's parents and grandparents). Circadian characteristics and descriptive statistics for the three circulatory variables were used for classification by a so-called "monotest", an all-subsets variable selection technique for biomedical discriminant analysis. For a particular combination of variables, the "monotest" performs as many steps of separate analyses as the total number of subjects, each subject's data being compared as a set with those of all others ("leave-one-out" approach). When the circadian amplitude of systolic blood pressure was used as classifier, the "monotest" yielded a 63% classification equivalent to prior criteria, the latter being based on a negative or a positive family history of high blood pressure. The "monotest" complements rhythmometric procedures and defines a set of individualized criteria for risk assessment. The combined use of automatic hardware for time-specified sampling with proper software for signal processing and discriminant analysis allows to recognize parameters of blood pressure circadian variability as a source of information for neonatal classification according to cardiovascular disease risk.