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Pulmonary hypertension with bronchopulmonary dysplasia: Aichi cohort study.

BACKGROUND
The incidence of pulmonary hypertension (PH) associated with bronchopulmonary dysplasia (BPD) has not been investigated in regional cohorts. The aim of this study was to clarify the incidence of PH associated with BPD in all very low birthweight infants (VLBWIs) born during the study period in Aichi Prefecture, Japan.


METHODS
We conducted a retrospective observational cohort study of all VLBWIs born in Aichi Prefecture. The inclusion criteria were VLB, birth between 1 January 2015 and 31 December 2015, and admission to any neonatal intensive care unit in Aichi Prefecture. BPD28d and BPD36w were defined as the need for supplemental oxygen or any respiratory support at 28 days of age or 36 weeks of postmenstrual age (PMA). The primary outcome was the incidence of PH after 36 weeks' PMA (PH36w) in VLBWIs with BPD28d and BPD36w. The secondary outcomes were the clinical factors related to PH36w in BPD36w patients. Mann-Whitney U-test and Fisher's exact test were used for univariate analysis. Differences were considered statistically significant at P < 0.05. Risk ratio (RR) and 95% confidence interval (CI) were also evaluated.


RESULTS
A total of 441 patients were analyzed. A total of 217 and 131 patients met the definition of BPD28d and BPD36w, respectively. Nine patients were diagnosed with PH36w (4.2% and 6.9% of the BPD28d and BPD36w patients, respectively). The presence of oligohydramnios (RR, 2.71; 95% CI: 1.55-4.73, P = 0.014) and sepsis (RR, 3.62; 95% CI: 1.51-8.63, P = 0.025) was significant in the PH36w patients.


CONCLUSIONS
The incidence of PH36w was 4.2% and 6.9% in the BPD28d and BPD36w patients, respectively. Oligohydramnios and sepsis were significantly associated with PH36w in VLBWIs.