Cardiovascular Risk in Hypertension in Relation to Achieved Blood Pressure Using Automated Office Blood Pressure Measurement

Abstract

T wo aspects of hypertension that have received considerable attention in recent years are the threshold blood pressure (BP) for diagnosing hypertension and the optimum BP target after drug therapy has been initiated. In each instance, greater emphasis is now given to systolic BP, primarily because it has been shown in numerous studies to be the best predictor of cardiovascular risk. Thresholds for the initiation of therapy based on increases in future cardiovascular events in relation to BP have been determined 1-3 for 24-hour ambulatory BP monitoring, home BP, and electronic, automated office BP (AOBP). As for conventional manual office BP, treatment thresholds were mainly derived from placebo-controlled clinical trials. For example, in the SHEP trial (Systolic Hypertension in the Elderly Program), 4 hypertension was defined as a systolic BP of 160 mm Hg or higher, and the target BP was a decrease of at least 20 mm Hg to <150 mm Hg. This study provided evidence to support treating isolated systolic hypertension of 160 mm Hg or higher in the elderly. Clinical outcome data that would justify treating uncomplicated, mild diastolic hypertension (90-99 mm Hg) based on placebo-controlled clinical trials are lacking. Other epidemiological studies 5 have shown an increase in cardiovascular events in mixed treated and untreated populations starting at a BP ≥115/75 mm Hg. However, these findings only relate BP to the future risk of a cardiovascular event and do not address the optimum BP after drug therapy has been started. Overall, convincing evidence for initiating drug therapy for uncomplicated, mild hypertension (BP 140-159/90-99 mm Hg) based on office BP is limited.There has also not been a specific target BP for treating systolic hypertension, with some guidelines recommending a <150 mm Hg target in the elderly based on the results of the SHEP trial, whereas others have maintained the Abstract-The SPRINT (Systolic Blood Pressure Intervention Trial) reported that some older, higher risk patients might benefit from a target systolic blood pressure (BP) of <120 versus <140 mm Hg. However, it is not yet known how the BP target and measurement methods used in SPRINT relate to cardiovascular outcomes in real-world practice. SPRINT used the automated office BP technique, which requires the patient to be resting quietly and alone, with multiple readings being recorded automatically using an electronic oscillometric sphygmomanometer. We studied the relationship between achieved automated office BP at baseline and cardiovascular events in 6183 community-dwelling residents of Ontario aged ≥66 years who were receiving antihypertensive therapy and followed for a mean of 4.6 years. Adjusted hazard ratios (95% confidence intervals) were computed for 10 mm Hg increments in achieved automated office BP at baseline using Cox proportional hazards regression and the BP category with the lowest event rate as the reference category.

Attended and Unattended Automated Office Blood Pressure Measurements Have Better Agreement With Ambulatory Monitoring Than Conventional Office Readings

“…In addition to SPRINT, AOBP has also been used for cardiovascular outcomes in a Canadian study of older community‐dwelling people followed up for an average of 4.6 years. In this study, AOBP values of 110 to 119 mm Hg were associated with lower cardiovascular risk 9. We have also reported previously that AOBP predicts cardiovascular events equally well to other BP measurement techniques 10…”

Office blood pressure measurement in the 21st century

“…There was a progressive increase in cardiovascular events starting at a systolic BP of 110/60 mm Hg and becoming statistically significant at a threshold of 135/80 mm Hg. In a parallel study in 6183 treated hypertensive participants in CHAP followed for 4.6 years, the lowest rate of cardiovascular events occurred at an achieved AOBP of 110‐119 mm Hg, which is consistent with the benefits of treating to a systolic AOBP target < 120 mm Hg in SPRINT. Finally, SPRINT used the AOBP (or AOBP‐like) technique in demonstrating increased benefit for hypertensive patients at a higher cardiovascular risk when treated to a target systolic BP target < 120 mm Hg.…”

White-Coat Effect Is Uncommon in Patients With Refractory Hypertension

“…A BP cutoff of ≥ 135/85 mmHg for elevated BP was used based on recent literature validating automated BP devices 15,16 . Serial, automated, unattended BP measurements, as with the BpTRU device, have been shown to minimize white coat effects 15-17 .…”