Abstract-Whether target organ damage is associated with blood pressure (BP) variability independent of level remains debated. We assessed these associations from 10-minute beat-to-beat, 24-hour ambulatory, and 7-day home BP recordings in 256 untreated subjects referred to a hypertension clinic. BP variability indices were variability independent of the mean, maximum-minimum difference, and average real variability. Effect sizes (standardized β) were computed using multivariable regression models. In beat-to-beat recordings, left ventricular mass index (n=128) was not (P≥0.18) associated with systolic BP but increased with all 3 systolic variability indices (+2.97-3.53 g/m 2 ; P<0.04); the urinary albumin-to-creatinine ratio increased (P≤0.03) with systolic BP (+1.14-1.17 mg/mmol) and maximum-minimum difference (+1.18 mg/mmol); and pulse wave velocity increased with systolic BP (+0.69 m/s; P<0.001). In 24-hour recordings, all 3 indices of organ damage increased (P<0.03) with systolic BP, whereas the associations with BP variability were nonsignificant (P≥0.15) except for increases in pulse wave velocity (P<0.05) with variability independent of the mean (+0.16 m/s) and maximum-minimum difference (+0.17 m/s). In home recordings, the urinary albumin-to-creatinine ratio (+1.27-1.30 mg/mmol) and pulse wave velocity (+0.36-0.40 m/s) increased (P<0.05) with systolic BP, whereas all associations of target organ damage with the variability indices were nonsignificant (P≥0.07). In conclusion, while accounting for BP level, associations of target organ damage with BP variability were readily detectable in beat-to-beat recordings, least noticeable in home recordings, with 24-hour ambulatory monitoring being informative only for pulse
Assessment of Organ DamageAs described in detail elsewhere, 16 LVMI by echocardiography (n=128), the urinary albumin-to-creatinine ratio (n=256), and aortic PWV (n=255) were determined as measures of organ damage. For the details of the organ damage assessment and other measurements, including body mass index, serum cholesterol, plasma glucose, and questionnaire survey on smoking and drinking habits, see Expanded Methods in the online-only Data Supplement.
Statistical AnalysisFor database management and statistical analysis, we used the Statistical Analysis System software, version 9.3 (SAS Institute, Cary, NC). We limited our main analyses to systolic BP because systolic BP is the main driver of risk 17 and because we recently demonstrated in the same patient cohort that systolic BP was the main determinant of target organ damage irrespective of age. 16 Henceforth, in our article unless otherwise specified, BP refers to systolic BP. We assessed BP variability from the variability independent of the mean (VIM), 15 the difference between maximum and minimum BP (MMD), and average real variability (ARV).10,14 For the details of the computation of these variability indices, see Expanded Methods in the online-only Data Supplement.To study the association between organ damage and BP level and variabi...