-Patient characteristics
This study includes 274 newborns full-term,
critically ill and premature,
admitted to a neonatal intensive care unit (NICU) between september 2014 and september 2015,
both included.
This scientific exhibit divides newborns into 3 main groups: pre-term (70.75%),
term (28.89%) and post-term (0.36%).
The pre-term group was subdivided in extremely preterm (16.97%),
very preterm (19.85%) and moderate/late preterm (33.93%).
This classification is based on the WHO guidelines which define preterm birth as any birth before 37 completed weeks of gestation,
or fewer than 259 days since the first day of the women’s last menstrual period (LMP) and this can be further subdivided on the basis of gestational age: extremely preterm (<28 weeks),
very preterm (28–<32 weeks),
and moderate or late preterm (32–<37 completed weeks of gestation).
These subdivisions are important since decreasing gestational age is associated with increasing mortality,
and disability.
-Chest x-ray assessment
One chest x-ray was performed to 206 (75.2%) newborns; two chest x-rays were performed to 48 (17.5%) newborns during the first two consecutive days of life and three chest x-rays were performed to 16 (5.8%) newborns during the first three consecutive days.
Only 4 (1.5%) newborns had 4 chest x-rays performed during the first four consecutive days of life.
This is a cross-sectional study of 366 plain chest films of 274 newborns.
Three simple measures were obtained from chest A-P exams (Fig.1):
1.
Dorsal spine length (DSL): A straight line from the superior rim of D1 to the lower rim of D12.
2.
Right pulmonary length (RPL): From the right pulmonary apex to the right diaphragmatic dome.
3.
Transversal chest width (TCW): From the external surface of the right 8 or 9th rib to the contralateral external surface.
-Other relevant variables
Other variables were recorded in our scientific exhibit.
The gestational age,
weight,
twin pregnancy,
persistent ductus arteriosus,
congenital malformations,
metabolopathies,
premature newborn complications (hyaline membrane disease,
necrotizing enterocolitis,
respiratory distress syndrome or haemolytic disease of the newborn requiring phototherapy),
previous pregnancies and maternal complications (pre-eclampsia and eclampsia,
chorioamnionitis or threat of premature birth).
-Statistical analysis (Fig.2)
ROC analysis was performed to asses cut points for each measure to find optimal sensitivity and specificity for predicting gestational age.
ROC analysis was performed to asses best cut points for each measure to find optimal sensitivity and specificity for predicting gestational age.
ROC curves were drawn for each measure.
R squared correlation was calculated for each measure with the same measure in subsequent chest x-rays to asses if they differed substantially.
