Survival Analysis of Premature Infants Admitted to Neonatal Int ensive Care Unit (NICU) in Northwest Ethiopia using Semi-Parametric Fr ailty Model

Yehuala S Ayalew S

doi:10.4172/2155-6180.1000223

Abstract

In this research, the cox proportional hazard model and the semi-parametric gamma frailty model were compared on the survival of premature infants admitted to neonatal intensive care unit from December 29, 2011 to April 6, 2014. A retrospective study design was used to collect the data from patients chart. A frailty effect (θ=0.252, P-Value = 0.0031 < α=0.05) was obtained from the semi-parametric gamma frailty model, and mortality was depend within and across categories of premature infants based on their gestational age. The values of frailty were dispersed and hence induce greater heterogeneity in the infant hazards. Therefore, when there is heterogeneity, semi-parametric gamma frailty model could be used and lead to acceptable conclusions. Both models identifies Antenatal Care Visit, gravidity of (6-10), HIV status of mother, Respiratory Distress Syndrome, Prenatal Asphyxia, anemia and breastfeed initiated as the most determinant and statistically associated with time to death of premature infants admitted to NICU. Based on the model comparison analysis, semi-parametric gamma frailty was the best model to fit the data.

Highlights

Infants born before 37 completed weeks of gestation are known as premature or preterm infants
This study shows that the overall mortality of premature infants admitted to Neonatal Intensive Care Unit (NICU) in UoGH during the study period was 122(25.2%) and that was very satisfactory in comparison to the study carried out by Fakher et al, [29], 48% death of preterm infants admitted to NICU in Fawzy Moaz Hospital, Egypt
The log-rank test and Kaplan Meier curve for equality of survival distribution of categories of covariates shows that ANC, Gravidity, Parity, Weight of Infants, Gestational Age, Multiple Pregnancy, HIV status of Mother, Infant of Diabetic Mother (IDM), Gestational Age Vs Weight of infant, Breast Feeding Initiated, Hypothermia, Neonatal Sepsis, Respiratory Distress Syndrome (RDS), Prinatal Asphyxia (PNA), Anemia, Hypoglycemia, and Jaundice are statistically significant (P-Value < 0.05).The study shows that, we have enough evidence to say that the premature infants admitted to NICU survival distribution are different or the Kaplan Meier curves are statistically different with respect to categories of significant covariates

Summary

Introduction

Infants born before 37 completed weeks of gestation are known as premature or preterm infants. Premature infants come early into the world. They are born fragile, small and weighing less than full term infants. Preterm birth refers to the birth of a baby that occurs before 37 completed weeks of gestation. It can be further sub categorized as late preterm delivery from 34 to 36, moderately preterm from 32 to 34, very preterm less than 32, and extremely preterm less than 28 weeks of gestation WHO [1] and Offiah et al [2]. Premature birth is the major cause of prenatal morbidity and mortality all over the world [4]

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Conclusion