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A few studies indicated a relationship between age and circadian blood pressure (BP) variation. However, whether this relationship is independent or not was still unknown. Our aim was to determine the correlation between age and the circadian BP variation in a group of hypertensive adults.
Clinical data and 24-hour (24h) ambulatory BP monitoring were obtained from 297 consecutive adults with hypertension. All subjects had good technical quality 24h ambulatory BP monitoring with validated devices, according to the percentage of nocturnal BP fall, the extreme-dipping, dipping, non-dipping and reverse-dipping statuses were categorized. We classified the subtypes of nocturnal BP fall as follow: extreme-dipping (> 20% nocturnal decline in BP from the diurnal level), dipping (10% to 20% nocturnal decline in BP), non-dipping (0% to 9% nocturnal decline in BP), and reverse-dipping (< 0% nocturnal decline in BP or nocturnal elevation). We also collect other clinical data of patients, including medical history, biochemical variables, Evaluation of cardiac structure and function, etc.
Multivariate linear regression analysis identified that age independently and negatively correlated with the percentage of nocturnal systolic BP (SBP) fall (β = -7.296, 95% confidence interval (CI): -10.430, -4.162, P < 0.001). The reverse-dippers were the oldest and the extreme-dippers were the youngest. The age difference among the four BP dipping statuses was significant with and without the adjustment of the sex, body mass index, drugs, diabetes, smoking, 24h mean heart rate and 24h mean systolic and diastolic BP.
In conclusion, age independently correlated with the circadian systolic BP variation in hypertensive adults which suggested that a pattern of blunted nocturnal BP fall with ageing should be noticed in this population.