Long term visit-to-visit variability of systolic blood pressure and cardiovascular disease events in a primary care setting: a 10-year retrospective cohort study [Abstract OS 04-05]

Conference abstract:
OBJECTIVE: This study aims to determine the relationship of long term visit to visit variability (VVV) of SBP and cardiovascular disease (CVD) in a primary care setting.
DESIGN AND METHOD: This is a retrospective study of a cohort of 1416 patients over a period of 10 years (1998-2007). Demographic data, three monthly clinic BP readings and CVD events were captured from patient records. We derived the mean BP and VVV of SBPs for each subject and divided them into three groups defined as non hypertension, developed hypertension along the 10-year follow-up and persistent hypertension. We examined differences in cardiovascular events across these groups.
RESULTS: Mean age of the participants at baseline was 56.5 ± 10.1 years, 34.6% were males. Table 1 describes mean SBP, BPV and CVD events of the study population.Those with both low mean SBP and low BPV have the lowest CVD events, conversely those with both high mean SBP and high BPV have highest CVD events. In those patients with the same mean SBP, whether high or low, those with higher BPV have more events than those with lower BPV. However patients with low mean SBP but high BPV have more CVD events compared with those patients with high mean SBP but low BPV (p = 0.04) suggesting BPV is more important than mean SBP in causing CVD events.We used ROC of VVV SBP to identify the cut off point of 12.9 mmHg as the indicator for increase in CVD events.
CONCLUSIONS: In our study, we found that patients with hypertension have higher BPV than normotensive subjects. Furthermore those with higher BPV also had more CVD events. As such, we should prioritize lowering not only mean systolic BP but lowering BPV as well. Long term VVV SBP should be another target in the management of patients with hypertension.