BP measurements vary widely by setting, but intensive control still cost-effective, studies find
A review compared measurements of blood pressure (BP) in research, office, and other settings and found that systolic BP results vary significantly, but a new study showed that intensive BP control targets are nonetheless cost-effective for high-risk patients.
Recent studies examined the variable accuracy of methods to measure blood pressure (BP) and the cost-effectiveness of targeting lower BPs given variable readings.
The first study was a systematic review and meta-analysis of 65 studies with 40,022 participants comparing BP results with various methods of measurement using office BP measurement as reference. Participants were not pregnant, at least 18 years old, and had measurements by at least two of the following methods: research office, automated office, convenient office, ambulatory, and home. The review was published by Annals of Internal Medicine on Aug. 19.
Compared with measurement in a research office, systolic BP was significantly higher with convenient office measurement (pooled mean difference, 2.69 mm Hg; 95% CI, −0.13 to 5.51 mm Hg) and lower for the other measures (mean difference, 4.57 mm Hg [95% CI, 2.54 to 6.60 mm Hg] with automated office; 4.59 mm Hg [95% CI, 2.83 to 6.34 mm Hg] with home; 4.22 mm Hg [95% CI, 2.62 to 5.82 mm Hg] with daytime ambulatory; 18.14 mm Hg [95% CI, 16.21 to 20.06 mm Hg] with nighttime ambulatory; and 8.63 mm Hg [95% CI, 6.97 to 10.28 mm Hg] with 24-hour ambulatory). Higher reference BP levels were associated with larger differences between research office and other measurement methods.
The findings show that the differences among methods are not fixed but instead depend on the underlying systolic and diastolic BPs, the study authors said.
A second study concluded that, for patients at high cardiovascular risk without diabetes or prior stroke, a systolic BP target of less than 120 mm Hg seems cost-effective across most settings with measurement error. Researchers performed a microsimulation model varying systolic BP measurement error based on data from the Systolic Blood Pressure Intervention Trial (SPRINT) and published literature. They determined incremental cost-effectiveness ratios for systolic BP targets of less than 120 mm Hg, less than 130 mm Hg, and less than 140 mm Hg. The study was also published Aug. 19 by Annals of Internal Medicine.
With research-grade measurement (mean error, 0 mm Hg), the incremental cost-effectiveness ratio was $24,400 per quality-adjusted life-year (QALY) for the target of less than 120 mm Hg versus less than 130 mm Hg, according to the study. With average measurement error of 7.3 mm Hg and a target of below 120 mm Hg, it increased to $42,000 per QALY. It rose to more than $100,000 per QALY in scenarios with high error (mean error, ≥14.6 mm Hg with a <120 mm Hg target), when an inflection point for increasing risk for cardiovascular disease was at or above 116 mm Hg, and in scenarios with a medication-taking disutility of at least 0.003 per antihypertensive medication.
An editorial associated with both studies said their data should “help alleviate clinicians' hesitancy to embrace lower BP targets.”