This study was approved by the Ethics Committee of the Institution (Ethics Committee for Research Project Analysis of the Clinical Board of Hospital das Clínicas and Faculdade de Medicina da Universidade de São Paulo) through research protocol 1383/09 and later adopted by the other institutions. Categorical data are shown with frequency distribution, and continuous data using mean and standard Metformin in vitro deviation, as indicated. The univariate analysis
of categorical variables used the chi-squared or Fisher’s exact test, when indicated, whereas Student’s t-test was used for continuous variables. To calculate the risk, after determining the odds ratio (95% CI), logistic binary regression and backward stepwise multiple regression were performed using MedCalc (Medical Calculator) software, version 220.127.116.11. The statistical significance level was set at 5% (p < 0.05). A total of 1,097 newborns with BW = 400 to 999 g and GA < 33 weeks were admitted in 16 NICUs of the BNRN during the study period. Of these, 220 were excluded due to death or transfer during the first three days AZD6244 in vivo of life, malformations, and congenital infections; 494 newborns met the inclusion criteria with echocardiographic diagnosis of PDA and no information regarding the presence of symptoms. The infants were subdivided according
to the therapeutic approach, into: G1 – 187 (37.8%), G2 – 205 (41.5%), and G3 – 102 (20.6%) (Fig. 1). The characteristics of the population according to each study group is shown in Table 1;it can be observed that there were differences between the groups in relation to the GA, mean SNAPPE II score, frequency and time of mechanical ventilation, and occurrence of LONS. Regarding the analyzed outcomes, it was observed that mortality was higher in G1 (51.3%), while it was lower in G3 (14.7%). The highest incidence of BPD36wks (70.6%) and ROPsur (23.5%) was observed in G3, while the combined outcome death/BPD36wks was less frequent in G2 (58.0%). It was not possible to analyze the effects of the therapy used on the occurrence of NECsur, due to the very small number of cases, although a Vitamin B12 statistically
significant difference was observed between G1 and G2 (Table 2). The multivariate regression analysis showed no influence of the type of therapeutic approach on the probability of death or the occurrence of BPD36wks alone, rather only for the combined outcome death/BPD36wks. However, the following were identified as risk factors for the outcome of death: NECsur (OR 5.64, 95% CI: 1.03 to 30.7) and IVH-III/IV (OR 3.62, 95% CI: 1.30 to 10.11). For the male gender (OR 2.59, 95% CI: 1.33 to 5.02), LONS (OR 1.88, 95% CI: 1.00 to 3.54), GA (OR 1.49, 95% CI: 1.22 to 1.81), and time of MV (OR 1.04, 95% CI: 1.02 to 1.07) were factors related to the presence of BPD36wks. BW alone was a protective factor against the outcomes death and BPD36wks (OR 0.99, 95% CI: 0.99 to 0.99) (Table 3).