Making a diagnosis of hypertension and defining treatment threshold in very low birth weight infants' need revision?

Introduction: Recent evidence suggests that preterm birth is a possible risk factor for high blood pressure (BP) in later life. The most widely quoted blood pressure centiles for very low birth weight (VLBW, <= 1500 g birth weight) infants at corrected term gestation is based on a cohort with mostly late preterm or term infants (Zubrow curves). Objectives: The objective of this study was to determine the clinical utility of the Zubrow curves in diagnosis of hypertension in VLBW infants at their term corrected gestational age (CGA). Patients and Methods: In a case-control study, we compared BP in 75 VLBW infants at 40 weeks CGA (cases) to 69 full term infants admitted to neonatal intensive care unit (NICU) (controls). Results: In spite of having lower weights, VLBW infants compared to term infants (2612.8 +/- 546 vs. 3308.2 +/- 373 g, P <= 0.001) had higher average systolic (88.8 +/- 7.6 vs. 82.33 +/- 8.5 mm Hg; P <= 0.001) and mean BP (61.2 +/- 6.6 vs. 57.61 +/- 6.9, P = 0.01). Although 41% (31/75) VLBW infants would have met the criteria for hypertension according to Zubrow curves only 4% (3/75) were diagnosed with hypertension. Conclusion: Since Zubrow BP centiles were based on a heterogeneous population of infants including preterm and term infants, new BP centiles based on chronological data from VLBW infants would allow a better definition of hypertension in these infants and identify the threshold BP for initiating treatment.