Monitoring blood pressure is crucial for assessing cardiovascular health and predicting future health outcomes. While clinic blood pressure measurements have been the standard approach, they may need to provide a comprehensive picture of blood pressure fluctuations throughout the day.
In contrast, ambulatory blood pressure monitoring offers a more comprehensive assessment by continuously measuring blood pressure over 24 hours. It has been suggested that ambulatory blood pressure monitoring is more effective in predicting health outcomes than clinic or home blood pressure measurements.
Evidence supporting ambulatory blood pressure’s impact on prognosis primarily comes from population-based studies and minor clinical investigations. However, these studies often had limitations, such as a limited number of participants or clinical outcomes, which hampered their ability to accurately determine the predictive value of clinic versus ambulatory blood pressure. Furthermore, more extensive studies often relied on pooling databases from previous smaller studies, which introduces potential biases.
The optimal period of ambulatory blood pressure monitoring (night-time, daytime, or 24-hour average) that is the strongest predictor of mortality remains uncertain. Some studies have indicated that night-time blood pressure might have the most significant predictive value, while others have yielded conflicting results.
In addition, the implications of hypertension phenotypes, such as white-coat hypertension (elevated blood pressure in a clinical setting) and masked hypertension (normal blood pressure in a clinical setting but elevated outside), on mortality risk have yet to be clearly defined. Previous studies’ limited number of deaths has restricted our understanding of these associations.
A new large-scale study published in The Lancet, comparing clinic and ambulatory blood pressure measurements, has found that ambulatory blood pressure monitoring provides more valuable information regarding the risk of all-cause death and cardiovascular death than conventional clinic blood pressure measurements.
The study, which included over 50,000 patients, revealed that once the 24-hour blood pressure was known, the predictive value of clinic systolic blood pressure significantly diminished, while associations with ambulatory blood pressure measures remained largely unaffected.
The study emphasized the superior predictive value of 24-hour ambulatory systolic blood pressure for mortality risk, nearly five times greater than clinic systolic blood pressure. Furthermore, night-time systolic blood pressure was about six times more informative for death than clinic systolic blood pressure and nearly twice as informative as daytime systolic blood pressure.
The findings also shed light on the impact of common blood pressure phenotypes on mortality. Masked and sustained hypertension was associated with an increased risk of death compared to patients with normal 24-hour blood pressure. However, white-coat hypertension did not show an increased risk of mortality when compared to individuals with blood pressure in the normal range.
The study supports previous research indicating that ambulatory systolic blood pressure better predicts death and cardiovascular outcomes than clinical systolic blood pressure. Notably, it expands upon these findings by examining the effects of hypertension phenotypes on mortality risk.
While previous studies have also demonstrated the superiority of night-time blood pressure over daytime blood pressure, this study further highlighted the standardized conditions during sleep that contribute to the nocturnal blood pressure’s predictive ability.
The results also indicated a J-shaped or U-shaped relationship between the clinic and ambulatory diastolic blood pressure and mortality, with increasing diastolic blood pressure showing a weaker association than systolic blood pressure. The study attributed the increased risk of death at lower diastolic blood pressure values to reverse causation related to arterial aging and subclinical disease.
The findings align with previous research showing the increased risks of death associated with masked and sustained hypertension. The delayed recognition and undertreatment of masked hypertension likely contribute to poorer outcomes in these individuals. On the other hand, the study suggests that white-coat hypertension does not pose an increased mortality risk compared to individuals with normal blood pressure.
The study acknowledges several limitations, such as the reliance on clinic blood pressure averages based on only two readings, potential variability in blood pressure measurements, and the absence of medication data during the follow-up period.
Additionally, the study focused on the predictive value of blood pressure monitoring and did not directly assess the benefits of treatment based on ambulatory blood pressure measurements. The predominantly White population studied may also limit the generalizability of the results to other races.
In summary, this large-scale study provides robust evidence supporting the more excellent predictive value of ambulatory blood pressure monitoring, particularly for systolic blood pressure, in predicting the risk of all-cause death and cardiovascular death.
The study highlights the importance of considering blood pressure phenotypes and emphasizes the need for further research to guide treatment decisions based on ambulatory blood pressure measurements.
This topic is very educative with its scientific evidence.