Risk factors for neonatal death in neonatal intensive care unit according to survival analysis Fatores de risco para óbito em unidade de terapia intensiva neonatal, utilizando a técnica de análise de sobrevida

Objective: To identify risk factors associated with death in infants admitted to neonatal intensive care unit of Taubaté University Hospital. Methods: This is a longitudinal study based on information from medical records regarding newborns admitted to the neonatal intensive care unit of Taubaté University Hospital. The outcome, either discharge or death, was the dependent variable. The independent variables were maternal and gestational variables: maternal age, hypertension, diabetes, corticosteroid therapy and delivery; the newborn variables: birth weight, gestation length, Apgar score in the first and fifth minutes of life, multiple birth, congenital malformations and gender; hospital variables: reports of mechanical ventilation, positive pressure ventilation, prolonged parenteral nutrition, sepsis, intubation, cardiac massage, phototherapy, hyaline membrane disease, oxygen and fraction of inspired oxygen. A model was built with three hierarchical levels for the survival analysis by the Cox model; the software Stata v9 was used, and the final model had variables with p value <0.05. The risks were estimated by the effect measure known as hazard ratio (HR) with 95% confidence intervals. Newborns transferred to other services during the hospitalization were excluded from the study. Results: Were admitted during the study period 495 newborns, with 129 deaths (26.1%). In the final model, only the variables of corticosteroid use (HR 1.64, 95% CI 1.02-2.70), malformation (HR 1.93, 95% CI 1.052.88), very low birth weight (HR 4.28, 95% CI 2.79-6.57) and Apgar scores lower than seven by 1 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 intubation (HR 2.28, 95% CI 1 .41-3.70). Conclusion: Factors related primarily to the newborn and the hospitalization (except corticosteroids therapy) were identified to be associated with mortality, highlighting a possible protective factor of phototherapy and the risk for very low birth weight infants.