DISCUSSION

In our investigations, it was observed that CRIB II score has a high value in prediction of premature neonates’ mortality with birth weight lower than 1500 g, in a way that, CRIB II score could predict 83% of mortality cases in premature neonates that shows a high value of this index. Measurement of this index is very easy and fast because all applied variables are of routine investigations of low weight neonates; also these variants are not affected by human errors. Since prediction of neonatal mortality with very low birth weight (less than 1500 gr) reveals an outstanding impact on medical interventions, in different studies, and various indexed were studied (5-9).

Felice et al (2005) studied 147 neonates with birth weight less than 1500 gr or gestational age less than 31 weeks. They evaluated CRIB, CRIB II, birth age and birth weight for prediction of neonatal mortality; according to AUC, these indexes could predict mortality between 86% (birth age) to 92% (CRIB). The researchers did not observe any difference between investigated indexes in prediction of neonatal mortality (10). As it was mentioned previously, in our study all indexes were valuable in prediction of neonatal mortality.

Although in previous studies and our investigation, CRIB II declared higher values in comparison with other indexes like birth age and birth weight, there are some studies that have evaluated CRIB II as less predictive, and other indexes though showed there was no significant difference. In Baumer et al’s study, between 1991 to 2006, 1485 premature neonates were studied. In this investigation based on AUC, CRIB 82%, birth weight 74%, birth age 71% and CRIB II 69% could predict mortality cases. Although there was no statistically significant difference between the indexes, CRIB II has lower value compared to other indexes. Asthere is no clear reason for these observations, researchers believe in the need for further studies (11).

Low birth weight and low gestational age are two main causes of numerous disorders in these neonates; also these two are the main reason for mortality in infancy and the first year after birth (12). Disease severity of the neonate at hospitalization time and some laboratory findings like Base deficiency rate are associated with the prognosis of the neonates. Application of CRIB as a simple way for evaluation of illness severity during hospitalization that can estimate the relative risk of neonatal mortality (13, 14).

In a survey to evaluate the CRIB II value for prediction of mortality rate of premature neonates in comparison with birth weight and gestational age, 97 neonates were investigated. The area under the ROC diagram was almost equal for birth weight, gestational age and CRIB II. The result of this research showed that the predictive value of CRIB II score in prediction of mortality rate in premature neonates is not more than birth weight and gestational age (15).

Mortality rate of premature neonates is evaluable by CRIB II. In an investigation to compare the ability of CRIB, CRIB II, birth weight and gestational age in prediction of premature mortality, 1,485 neonates were studied. The area under the AUC graph was 82% for CRIB, 74% for birth weight, 71% for gestational age, and 69% for CRIB II. The results of this investigation showed that CRIB II does not have any priority over birth weight, gestational age and CRIB in determination of mortality rate of premature neonates (16).

In an investigation to assess the ability of CRIB in determination of long-time prognosis of neural development in premature neonates, 455 neonates were studied. 386 neonates (89%) survived until clearance from hospital and 352 neonates (91%) were investigated mentally when they were 1 year old. There were 76 neonates (22%) with a major neural disorder. Higher CRIB score was assigned with major neural disorder (17). In addition, in another investigation, neonates with 13 CRIB II score or more at first hour after birth had major developmental disorders (18).

In another study which was conducted in Gorgan university of medical sciences, in order to evaluate the prognostic power of CRIB score in prediction of the consequence of premature VLBW neonates, 46 neonates with gestational age less than 37 weeks and birth weight lower than 1500 gr were assayed. Mortality rate in this research was 37% and the most prevalent reason of death was respiratory failure. The mean of birth weight, gestational age and the mean of CRIB score in the group of survivor neonates and non-survivor neonates was 1201, 934 gr and 30 and 28 weeks, and 3.76 and 11.47 respectively (19). In our investigation, CRIB II scoring system was used to determine the mortality risk in neonates with birth weight less than 1500 gr. The powerful point of the present study was that all mentioned variables in this study are measured routinely in all neonates with birth weight less than 1500 gr, and we did not need any further interventions. Considering this point, that neonatal state at first hours after birth is related to midwifery and obstetric issues of mother and problems of the neonate, the measurement of these variants at first hours after birth can be valuable in prediction of mortality and also higher score in CRIB II shows higher risk of mortality for neonate. About the birth weight variant in prediction of neonatal mortality, it should be said that, although for a long time it has been used as an index in determination of neonatal mortality, numerous studies have shown that prognosis of neonates with equal weights in NICU of different hospitals are different and that can be related to the applied equipment in these units, proportion of nurses to patients and other factors.

Limitations of the Study
The main limitation of our study was clearance of the neonates with personal satisfaction of the parents before conduction of the study and this issue was solved by substitution of other neonates.

CONCLUSIONS

According to our findings in this study, CRIB II has a higher value in mortality prediction of the neonates with birth weight lower than 1500 gr in a way that, it could predict 83% of mortalities in premature neonates with birth weight lower than 1500 gr and this shows the high value of this index. Since the prediction of neonatal mortality in VLBW neonates (less than 1500 gr) has a high value in medical interventions, CRIB II score is a trustable tool in neonatal mortality prediction and their classification is to make priority for medical interventions especially in absence of medical facilities.