Archief Roodbont

These results suggest that daytime blood pressure, adjusted for nighttime blood pressure, predicts fatal combined with nonfatal cardiovascular events, except in treated patients, in whom antihypertensive drugs might reduce blood pressure during the day, but not at night. One reason for this could be that antihypertensive treatment acts as a major confounder, the researchers suggest. Patients with more severe hypertension or a history of cardiovascular complications are more likely to be treated and at higher risk than other patients, and they take their medications during daytime, and that activity that lowers blood pressure wears off at night. This mechanism leads to a reduced daytime blood pressure, increased nighttime blood pressure, and a decreased night-to-day blood pressure ratio.

Participants with systolic night-to-day ratio value of ≥ 1 or more were older, at higher risk of death, and died at an older age than those whose night-to-day ratio was normal (≥ 0.80 to < 0.90). The researchers suggest that higher nighttime than daytime blood pressure might be a marker rather than a cause of a poor outcome.
Conclusion

Dr. Boggia and his colleagues say that the findings of this study support the conclusions that:

* Ambulatory blood pressure should be recorded during the whole day;

* Clinical decisions should be based on diagnostic thresholds for the 24-hour blood pressure rather than the dipping pattern; and

* Antihypertensive drugs should be administered so that the blood pressure is lowered over 24 hours, so that a normal night-to-day blood pressure ratio is preserved.

However, the researchers point out that there is no evidence supporting the efficacy of chronotherapy in terms of blood-pressure control or outcome. Furthermore, the classification of patients according to the night-to-day blood pressure ratio greatly depends on arbitrary criteria, is poorly reproducible, and has a different prognostic meaning according to the disease outcome under study, the prevailing 24-hour blood pressure level, and treatment status. They recommend that "in future publications any categorical representation of the night-to-day ratio be supported by continuous analyses adjusted for the 24-hour blood pressure and be stratified for treatment status."
Comment

In an invited commentary on the study,[11] Stéphane Laurent, MD, PhD (Hôpital Européen Georges Pompidou and Université Paris-Descartes, Paris, France) agrees with Dr. Boggia and colleagues that the main finding, that daytime blood pressure independently predicts the composite of fatal and nonfatal outcomes, might not apply to patients with treated hypertension. Although the investigators did not include cohorts of patients with hypertension and selected general populations instead, Prof. Laurent notes, 22% of the overall study population were being treated for hypertension at baseline and analysis of a significant interaction with antihypertensive treatment status at enrollment was possible.

The contrasting findings in untreated participants and treated patients suggest a need for an additional meta-analysis of individual data for ambulatory blood pressure that includes a substantial number of patients on treatment for hypertension, Prof. Laurent suggests. "Although the findings of Boggia and colleagues are in favor of recording the ambulatory pressure for the whole day, the question arises as to whether 24-hour blood pressure values from patients taking antihypertensive therapy should be interpreted differently from those of untreated participants," he proposes. He believes that the results of the study may have importa