The objective evaluation of an infant’s health status is important not only for the care the newborn requires but also for scientific research. The need for an unambiguous and comparable record of such an assessment led to the invention of a clear numerical scale. Virginia Apgar was the first to propose a measure of an infant’s health status that is quantitative, and therefore applicable in medical research.
To assess the health status of infants born prematurely and those requiring medical interventions, Rudiger et al. suggested a modification of the AS (the specified AS). The modification aimed to relate the AS to the GA, but it was independent of the requirements to achieve the score [13, 14]. Hence, an infant born full-term or prematurely, who has no problems adapting to extrauterine life or who reacts favourably to resuscitation or other interventions, obtains the maximum specified AS.
The rapid progress observed in the field of neonatology in the last decades, the expanding knowledge base, and technological developments have resulted in increased survival of newborns. This has led to a significantly greater number of medical procedures undertaken immediately after birth. These procedures and their outputs should not be omitted in the health assessment of newborns [13, 15, 16]. Our results confirm the link between the interventions undertaken immediately after birth and the health status later in life. In 2006, the AAP Committee on Foetuses and Newborns and the ACOG Committee on Obstetric Practice proposed an expanded AS to account for these interventions and their effects [2, 16]. This scale contains, along with the classical AS, a listed course of resuscitation procedures. In use since 2008 in the Neonatal and Intensive Care Department of the Medical University of Warsaw, the expanded AS has significantly improved the precision of the documentation of the resuscitation procedures. It has also decreased the subjectivity of the health status evaluation of newborns. Therefore, this score was used in our study.
Further developments in the health assessment of newborns include the combined AS developed by Rudiger and Aguar, which merges the specified and expanded AS and assigns numeric values to the descriptive components of the expanded AS . Dalili et al. compared the four types of AS and concluded that only a low score according to the combined AS predicts the incidence of IVH and its neurological complications in infants with perinatal hypoxia . A low combined AS at 5 minutes after birth has been independently linked to IVH incidence. However, it does not indicate the severity of IVH. These results agree with the ACOG and AAP, our results, and other published studies showing the low prognostic value of the classic AS on prospective neurological status or unfavourable health prognosis [18–23].
Our study was based on decision trees, which have several advantages over other decision algorithms. Their simple structure allows for an easy interpretation of the results. They enable the assessment of the importance of the variables and attributes and do not require assumptions regarding the specific distribution of the variables. The missing data do not cause problems in the analysis, and the classification based on decision trees is characterised by high accuracy. Additionally, the possibility of modelling dependencies of nonlinear phenomena and of analysing various sets of variables (nominal, ordinal, and continuous) allows for greater precision and detail in the description of the infants’ health status and the undertaken interventions. The decision tree algorithm suited our study goals and setup because we required i) a simple data representation structure, ii) the possibility to analyse various sets of variables (nominal, ordinal, and continuous) with non-normal distribution, and iii) a high-accuracy classification system.
Our CHAID-based analysis shows the importance of the concentration of the oxygen supplied after birth in the prognosis of IVH/IPH incidence in premature infants. In score-only-based systems this information is lost. The combined AS only considers the presence or absence of oxygen supply. In our analysis, we defined the thresholds for the selection of the groups of newborns for whom the health status prognosis can be made. Nevertheless, this is only a preliminary study that focuses on the prognosis of IVH and IPH incidence based on an infant’s health status after birth. The GA and the birth body weight are the most important risk factors for complications such as IVH, ROP, and BPD. Although these diseases have complex pathogenesis, the states of blood supply and oxygenation of cells and tissues are the key influencing factors [24, 25].