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[Incidence and risk factors of bronchopulmonary dysplasia in premature infants in 10 hospitals in China].

OBJECTIVE
To determine the incidence of bronchopulmonary dysplasia (BPD), risk factors for development of BPD and severity of BPD among 10 neonatal intensive care units (NICU) in China.


METHODS
Data were retrospectively collected from 10 NICU in China between Jan. 1(st) 2006 - Dec. 31(st) 2008. All babies whose gestational age was < 37 w and survived over 28 d were included in this study. BPD was diagnosed according to the Bancalari criteria which was oxygen dependency at 28 days of age. The incidence of BPD was calculated at different gestational age. All clinical features, maternal and neonatal risk factors, total fluid intake ad total caloric intake, percentages of weight loss from day 1 to day 10 of life were compared between non-BPD and BPD patients. BPD was classified as mild, moderate and severe according to the Bancalari criteria. All clinical features, maternal and neonatal risk factors were compared in patients with BPD. The risk factors for development of BPD and moderate/severe BPD were analyzed by logistic regression test.


RESULTS
Altogether 12 351 preterm babies were included. Among them 156 cases met the criteria of BPD. The incidence of BPD was 1.26%. The incidence of BPD in gestational age (GA) ≤ 28 w, 28 w-, 30 w-, 32 w- and 34 w- < 37 w were 19.3%, 13.11%, 5.62%, 0.95% and 0.09%. The incidence of BPD decreased dramatically with gestational age increase. Multivariate logistic regression model showed the risk factors for BPD were birth weight less than 1.5 kg, PDA, anemia of prematurity, RDS, CMV infection, mechanical ventilation, duration of mechanical ventilation ≥ 7 d and PaO2/FiO2 < 300. Among 156 BPD cases, 20 were excluded for incomplete data, 136 were included; 71 of the 136 patients (52%) had mild BPD while 65 of 136 patients (48%) had moderate/severe BPD. Multivariate logistic regression model showed the risk factors for severity of BPD were nosocomial infection (OR: 4.587; 95%CI: 2.104 - 10.004), CMV infection (OR: 4.440; 95%CI: 1.519 - 12.975); duration of mechanical ventilation ≥ 7 d (OR: 2.435; 95%CI: 1.113 - 5.330).


CONCLUSIONS
The incidence of BPD was 1.26%. The incidence of BPD decreased dramatically with gestational age increase. The risk factors for BPD were birth weight less than 1.5 kg, PDA, anemia of prematurity, RDS, CMV infection, mechanical ventilation, duration of mechanical ventilation ≥ 7 d and PaO2/FiO2 < 300. The most important risk factors for moderate/severe BPD were nosocomial infection, CMV infection and duration of mechanical ventilation ≥ 7 d.