Recently, the concept and methodology of the risk approach for maternal and child health have been developed by the World Health Organization and its world wide application and research are being strongly recommended.
The risk approach which is defined by W.H.O as a managerial tool for the flexible and rational distribution of existing resources, and for developing the appropriate content of maternal and child health care necessitates the development of a technique for the measurement of the individual and community risks in order to be able to classify them into groups by the amount of need for health care.
Numerous recent studies have focussed on the identification of relevant risk factors and the definition of normal and adverse outcomes of pregnancy and on how to assign a score to each factor for the quantitative assessment of risk factor as a determinant of pregnancy outcomes.
The methodology currently being used to construct a Score Chart may be classified into three broad fields, that is,- (1) Arbitrary method (2) Linear discriminant function method and (3) Regression method.
The arbitrary method has disadvantages such as lack of theoretical soundness and objectivity.
As for the linear discriminant function and regression methods, the need for computer for sophisticated calculation and the requirement of some practically unlikely statistical assumptions are the main disadvantages to be tolerated.
Furthermore, most of the scoring system construction were made in and for the hospital setting where modern clinical and computational facilities are available. From an extensive review on the past pros and cons on scoring system so far developed a conclusion could be derived that the system should be individualized for the population it is for and that any such system to be acceptible to primary care level health workers it should be simple in theory, take little time to use, and must be easily constructed even at the level of local community where sophisticated computational tools are not available. The authors suggest a trial of a new approach for constructing risk scores which may be called as a scoring system on the basis of the likelihood method.
The likelihood method, in principle, is a statistical tool which is designed to calculate the probability (or likelihood) of having a set of observed values under various models and the model for which the probability is the maximum will be chosen as the most appropriate one.
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In case of applying the likelihood method to risk scoring system, the "set of observed values" will be equivalent to the result of clinical check in the prenatal period, and the models will be the spectrum of adverse effect of pregnancy extending from healthfulness to mortality. A total of 1,500 pregnant women´s medical records at the Department of Obstetrics and Gynecology, National Medical Center, Seoul have been surveyed.
From the records, a total of 45 antepartum and intrapartum risk factors were checked for each patient as prospective determinants of postpartum outcomes.
Of those the following 11 factors were identified as having significant power for discriminating the pregnancy outcomes into normal and adverse groups.
( 1) No. of cesarean-section
( 2) Experience of abnormal presentation
( 3) Reasons for visit
( 4) Chief complaints
( 5) Systolic blood pressure
6) Heart status
( 7) General appearance
( 8) Edema status
( 9) Uterine cervix status
(10) Pelvic status
(11) Diagnosis of any other abnormality
On the basis of these 11 risk factors, on "M.C.H. risk factor discriminant score chart" was developed as presented in Table 4 (Ref. main text).
It was learnt that among 34 remaining factors which were assessed from this study as less or none predictive, there are many clinical symptoms or signs such as Rh type, mother´s weight, hemoglobin level, e.t.c., which are being widely recognized as important warning signs in clinical practice.
This result may be fundamentally attributable to the following two reasons.
(1) The criteria set for the classification of pregnancy outcomes into "normal" and "adverse" groups was on the basis of combined outcomes from both fetal and maternal sides, such that some risk factors which might have been identified as predictive when only one side were taken as criteria were cancelled out by such combination of outcomes.
(2) These were some risk factors whose positive rates were very low, say less than 1% so that the pridictive power based on the likelihood method became weaken seriously.
The recommendation for the future development of risk score chart based on the likelihood
method is to classify the pregnancy outcomes according to the following criteria.
(1) intrapartum outcomes:
1) Adverse outcome group based on fetal variables
2) Adverse outcome group based on maternal variables
3) Normal group
(2) Postpartum Outcomes:
1) Adverse outcome group based on fetal variables
2) Adverse outcome group based on maternal variables
3) Normal group
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