24-h Systolic blood pressure and heart rate recordings in lean and obese adolescents

OBJECTIVE: We assessed the hypothesis that differences in day and night-time systolic blood pressure (SBP) and heart rate (HR) recordings were smaller in obese versus lean children and adolescents, and whether measurements obtained during a school week or during weekends or holidays influenced these nocturnal falls. We also wanted to determine whether the results were influenced by gender. METHODS: Ambulatory 24-h BP and HR measurements were performed in 80 subjects, 51 girls and 29 boys. Lean (n = 25) and obese (n = 55) subjects were classified according to body mass index (BMI)-standard deviation (SD) criteria. Forty-eight subjects had their 24-h recordings performed during a school week and 32 during leisure time. RESULTS: The SBP nocturnal dipping response was less pronounced in obese subjects (16.2 +/- 6.3 mmHg) compared with lean controls (21.1 +/- 5.7 mmHg) (P < 0.01) of which the girls constituted most of the difference. HR change between day and night was similar in both groups being approximately 15 b/min. A small but statistical negative correlation was observed between BMI-SD and nocturnal fall in SBP (r = -0.3, P = 0.0065). In all subjects, regardless of BMI-SD, daytime SBP was higher when readings were obtained during a school week (123 +/- 7 mmHg) than during weekends or holidays (119 +/- 7 mmHg) (P = 0.029). CONCLUSION: Obese children and adolescents showed smaller nocturnal falls in SBP compared with lean subjects. This pattern may cause increased cardiovascular loading; thus, it may reflect an early sign of high blood pressure development and adds to cardiovascular risk in young obese individuals.