A resting systolic BP that consistently and chronically exceeds 120-125 mmHg may comprise an important threshold signaling vascular remodeling and emergent hypertension (HTN) at any age, according to results of a recent study published in JAMA.
Since the 1970s, when an acceptable systolic BP equaled patient age plus 100 mmHg, the understanding of BP has evolved substantially. In the 1970s, increased systolic BP was considered a byproduct of age.
More recent experimental data indicate that increased systolic BP can be delayed or circumvented through health maintenance. Once BP begins to rise, however, it rises at a rapid rate.
In this study, Teemu J. Niiranen, MD, Division of Medicine, Turku University Hospital, Turku, Finland, and colleagues analyzed data from the original cohort of the Framingham Heart Study to determine a threshold above which BP increases rapidly on its way to HTN. For this longitudinal, community-based, epidemiologic study, BP measurements were taken every 2 years between 1948 and 2005. Two measurements were obtained manually during each examination and an average of these two values was calculated to determine a final BP value.
HTN was defined as a BP greater than or equal to 140/90 mmHg or the use of antihypertensive medications documented during two or more consecutive examinations. Researchers ceased to acquire data in patients once they were classified as hypertensive.
To reduce any possible effects of age, time, and birth cohort, Dr. Niiranen and colleagues excluded participants who were older than age 40 at baseline BP measurement, had baseline HTN, went to less than three exams before HTN onset, and who developed HTN before 40 or after 80 years of age.
Participants were categorized based on the age of onset of HTN as follows:
- between 40 and 49 years
- between 50 and 59 years
- between 60 and 69 years
- between 70 and 79 years
- or no age of onset
Dr. Niiranen and co-authors analyzed data from 1,252 participants (mean age: 35.3 years; 63.1% female) from whom 16,072 BP measurements were collected. Participants contributed at most 28 serial resting BP measurements.
These researchers found that before the onset of HTN, BP was more or less stable. In addition, they observed that BP rose rapidly beginning at the following systolic BP levels in the following age groups:
- 123.2 mmHg (95%CI: 122.7-130.1 mmHg) at 40-49 years
- 122.0 mmHg (95%CI: 120.3-123.9 mmHg) at 50-59 years
- 124.9 mmHg (95%CI: 120.2-127.9 mmHg) at 60-69 years
- 120.5 mmHg (95%CI: 118.0-123.2 mmHg) at 70-79 years
According to the authors, because this study relied on statistical modeling, one limitation is the oversimplication of data interpretation. More research with larger cohorts is needed to assess and validate the generalizability of the results. Additionally, serial BP measurements in these larger cohorts should begin earlier in the participant’s life.
“Overall, our findings outline a possible framework for understanding life-course trends in arterial aging,” wrote Dr. Niiranen and co-authors, “which may have implications for managing BP in practice. In particular, our results suggest that the onset of clinically important BP elevation may be delayed despite aging. However, further investigations are still needed to unravel the sequence of hemodynamic and vascular changes occurring before hypertension onset.”
Finally, the authors suggest that to decrease the burden of HTN, interventions focused on the prevention of the rise of systolic BP should be investigated.