Factors Predicting the Fall in Clinic Blood Pressure on Repeated Measurements

Aim Clinic blood pressure (BP) readings tend to decrease towards the true value on repeated measurements. We aimed to identify factors associated with the fall in systolic and diastolic BP on repeated measurements. Methods We used BP data on 4943 participants aged ≥20 (2475 men, 2468 women; mean age±SD, 50±18 years) in the United States National Health and Nutrition Examination Survey (NHANES) 2007-8. Repeated measurements analysis of variance was used to identify predictors of the change in BP with time. Results As expected, BP was significantly related to age, gender and body mass index (P<0.001). Both systolic and diastolic BP decreased significantly with time (P<0.001). These decreases were significantly related to age and the maximum cuff pressure (P<0.001). They were not related to body weight, arm dimension, triceps skinfold thickness, cuff size, and consumption of food, coffee and tobacco in the preceding 30 minutes. Conclusion Older persons and those with high systolic BP had larger decreases in BP on repeated measurements. Hence, adequate inflation of cuff and repeated measurements in the elderly are key factors for measuring clinic BP accurately.