Cuff-based SBP amplification shows bias, less variability

Cuff-based estimates of systolic blood pressure (SBP) amplification demonstrate proportional systematic bias and less individual variability regardless of the difference from invasive measurements, according to a recent study.

A team of researchers assessed patients undergoing coronary angiography. Participants had invasive SBP amplification (brachial SBP – central SBP) measured simultaneously with cuff-based SBP amplification using a commercially available central BP device (device 1: Sphygmocor Xcel; n=171; mean age 60 years, 70 percent men) and an outdated model of a central BP device (device 2: Uscom BP+; n=52; mean age 62 years, 83 percent men).

The mean differences between cuff-based and invasive SBP amplification were 4 mm Hg (p<0.001) and ‒2 mm Hg (p=0.10) for devices 1 and 2, respectively. The two devices both systematically overestimated SBP amplification at lower levels and underestimated at higher levels of invasive SBP amplification. However, a stronger bias was noted for device 1 (r, ‒0.68 vs ‒0.52; z, 2.72; p=0.008).

There was low concordance of cuff-based and invasive SBP amplification across quartiles of invasive SBP amplification, especially in the lowest and highest quartiles.

Notably, the root mean square errors were significantly lower from regression between cuff-based central SBP and brachial SBP than from invasive regression models (p<0.001).

“These observations could provide insights on how to improve the performance of cuff-based central BP,” the researchers said.