Evidence for the relation between obesity and nocturnal blood pressure patterns

Obesity often leads to elevated blood pressure (BP) and hypertension, but its effect on nocturnal BP patterns has not been adequately examined. Therefore, the aim of this study was to examine the association between body mass index (BMI)/obesity and nocturnal hypertension and BP dipping. 6767 adult patients (53.6% females) were included in this study, measured for their weight and height to estimate BMI, and they categorized as normal weight, overweight or obese. A 24-hour ambulatory BP monitoring was also performed by all patients. Nocturnal hypertension was defined as >120/70 mmHg nocturnal systolic/diastolic BP. Patients were considered as dippers if BP dipping was >10% or non-dippers otherwise. Obesity was not significantly associated with nocturnal hypertension in multivariate analysis (OR:1.03, 95%CI: 0.78-1.36), but subgroup analysis revealed that obese treatment-naïve hypertensive patients had a 2.8 (OR:2.76, 95%CI:1.36-5.59) higher risk of nocturnal hypertension than normal-weight. Obese patients had also 42% (OR:1.42, 95%CI: 1.13-1.79) more risk of being non-dippers than dippers compared to those with normal weight, while subgroup analysis showed that this association was still present in treatment naïve (OR:1.43, 95%CI: 1.09-1.88) and under treatment hypertensive adults (OR:1.37, 95%CI: 1.11-1.68), but not in normotensives (OR:0.96, 95%CI: 0.75-1.22). Restricted cubic spline models did not show any significant non-linear association between BMI and nocturnal SBP, DBP, or dipping (p for non-linearity > 0.05). These results indicate that high BMI is associated with disturbed nocturnal BP patterns, a relationship that is more profound among hypertensive adults.