Presented at the Neonatal Society 2015 Summer Meeting.
Ocansey S1, Parkinson J1Holmes E2, Ozanne S3, Modi N1
1 Section of Neonatal Medicine, Imperial College London
2 Division of Surgery, Oncology, Reproductive Biology and Anaesthetics, Imperial College London
3 Department of Clinical Biochemistry, University of Cambridge
Background: Preterm birth and survival rates are rising globally, with a number of epidemiological studies demonstrating a clinically relevant increase in blood pressure (BP) in children and adults born preterm, compared to those born at term (1). Ambulatory monitoring is considered a more reliable approach to assessing BP as it is less affected by the anxiety response that accompanies one-off or clinic measurements. Here, we test the null hypothesis that no differences exist in clinic or ambulatory BP readings between ex-preterm and term born young adults.
Methods: This study represents an interim analysis of an ongoing BHF funded study “The preterm baby as a young adult” (REC: 12-LO-1053). Young adults (aged 19-27) born either prematurely (PT: <33 weeks gestation) or at term (T: 39-42 weeks gestation) attended for a single visit. A digital sphygmomanometer was used to measure BP after subjects had rested in a seated position for 5min. An average of 2-3 readings was used to calculate clinic systolic (SBP) and diastolic blood pressure (DBP). Ambulatory monitoring was obtained over 24h using a digital monitor. The difference between clinic and “day” ambulatory BP measures was calculated for each individual.
Results: Data was extracted from for 78 individuals (39 PT (27F); 39 T (23F). Ex-preterm adults demonstrated significantly increased SBP (PT: 127.2 ± 8.8mmHg; T: 118.6 ± 7.0mmHg, p<0.001) and DBP (PT: 76.6 ± 8.4mmHg; T: 72.7 ± 7.8mmHg, p=0.03) compared to term born controls, with no differences in ambulatory BP. Both female and male ex-preterms demonstrated significantly greater SBP compared to their respective term born controls (Female PT: 125.6 ± 7.5mmHg; Female T: 118.0 ± 7.6mmHg, p<0.001; Male PT: 131.3 ± 10.4; Male T: 119.4 ± 6.0, p<0.001). Female ex-preterms also presented increased DBP compared to their term born controls (p<0.01). The difference between clinic and ambulatory blood pressure was significantly increased in ex-preterm women compared to their term born counterparts (SBP: F PT: 10.9 ± 7.4mmHg, F T: 4.8 ± 7.5mmHg, p<0.01; DBP: F PT: 5.5 ± 8.0; F T: -0.4 ± 6.2mmHg, p<0.01) with no differences observed in men.
Conclusion: These interim data support previous studies reporting increased clinic SBP and DBP in ex-preterm individuals, with no differences in ambulatory blood pressure (1). These results corroborate smaller, female only studies (2) demonstrating female ex-preterm adults show an increased BP response to the anxiety of clinical BP measurement. Together with previous studies indicating gender specific trajectories in outcomes of preterm birth (3), these data indicate that future studies examining the long-term effects of preterm birth should be sufficiently powered to detect sex-specific effects.
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1. Parkinson JR et al. (2013) Pediatrics 131(4):1240-1263.
2. Kistner A et al. (2005) Pediatric Nephrology. 20(2):232-233.
3. Thomas EL et al. (2011) Pediatric Research 70(5):507-512.