The Conduit Artery Function Evaluation (CAFE) study used an FDA approved non-invasive Sphygmocor system to estimate central aortic pressure by examining blood pressure variables at the wrist. This was done in a cohort of 2,199 people from the original 19,257 individuals in the ASCOT Study.
This study found that aortic systolic blood pressure was lower by 4.3mmHg in the amlodipine arm compared to the atenolol arm, despite arm blood pressures that were "virtually the same". The authors conclude that treating hypertension with an amlodipine based treatment is therefore favourable. One of the authors states, "The assumption has been that all types of blood pressure treatments are equally effective. We show that this assumption is untrue."
From what we already know about ASCOT there were blood pressure differences between the two arms of the study of 2.7/1.9mmHg on average over the duration of the study. Articles in the Lancet and BMJ that have already been covered on this website have also raised this discrepancy and it has been estimated that this difference could account for half to all of the differences found between the two arms in the original ASCOT Study.
There is no indication that these differences have been corrected for in the sub-group study, although using statements that blood pressures were "virtually the same" intimates that no corrections were made. It is unknown what the results of this study would have shown if the blood pressures in the two arms of the study had been identical. It is also unclear exactly what the place of aortic blood pressure estimation should be in the treatment of hypertension.
This study is perhaps of academic interest to those who are at the very cutting edge of hypertension diagnosis, management and innovation. It does not apply to current management on hypertension in primary care. It does however continue the ASCOT hype.
Action: Clinicians should continue to follow NICE Guidelines to diagnose and manage hypertension in primary care.