Risk factors for neonatal death in neonatal intensive care unit according to survival analysis

To identify risk factors associated with death of infants admitted to neonatal intensive care unit of Taubaté University Hospital.

It is a longitudinal study with information obtained from medical records of newborns admitted to the neonatal intensive care unit of Taubaté University Hospital. Type of outcome, discharge or death, was dependent variable. The independent variables were maternal and gestational variables: maternal age, hypertension, diabetes, corticosteroid therapy and delivery; variables of the newborn: birth weight, gestation length, Apgar score in the first and fifth minutes of life, multiple birth, congenital malformations and sex; hospitalar variables: report of mechanical ventilation, positive pressure ventilation, reports of prolonged parenteral nutrition, sepsis, intubation, cardiac massage, phototherapy, hyaline membrane disease, oxygen and fraction of inspired oxygen. It was built a model in three hierarchical levels for the survival analysis by the Cox model; it was used the software Stata v9 and the final model contained variables with p <0.05. The risks were estimated by measure effect known as hazard ratio (HR) with confidence intervals of 95%. The newborns transferred during hospitalization to another service were excluded from the study.

There were admitted during the study period 495 newborns, with 129 deaths (26.1%). In the final model, only the variables of steroid use (HR 1.64, 95% CI 1.02-2.70), malformation (HR 1.93, CI 95% 1,05-2,88), very low birth weight (HR 4.28, 95% CI 2,79-6,57) and Apgar scores lower than seven of no1 min (HR 1.87, 95% CI 1,19-2,93) and 5 min (HR 1.74, 95% CI 1,05-2,88) and the variables phototherapy (HR 0.34; 95% CI 0,22-0,53) and endotracheal intubation (HR 2.28, 95% CI 1 .41-3, 70).

Factors related primarily to the newborn and the hospitalar internment (except therapy with corticosteroids) were identified as associated to mortality highlighting a possible protective factor of phototherapy and the risk of infants with very low birth weight.