By Eleanor McDermid, Senior medwireNews Reporter
The functional status of elderly people modifies the association between their blood pressure (BP) and cardiovascular disease (CVD) risk, a study shows.
The researchers found that CVD risk in elderly people rose with increasing systolic (S)BP and diastolic (D)BP, unless they were limited in their activities of daily living (ADL), in which case the association between CVD risk and DBP was reversed, with low DBP posing a problem.
“[O]ur findings shed light on the reasons for the inconsistent reports and current controversy on optimal BP levels in elderly people”, say lead researcher Carmen Peralta (San Francisco Veterans Affairs Medical Center, USA) and team.
The study participants were drawn from 2459 people who completed the seventh follow-up visit of the Cardiovascular Heath Study, at which point they were aged an average of 78 years. During a median of 8.5 years follow-up, they had 778 new CVD events.
In all, 18% of the participants had ADL limitation, assessed via a questionnaire. In these people, as well as in those without ADL limitation, higher SBP was associated with higher CVD risk, by 6% to 8% per 10 mmHg increase after accounting for confounders including use of antihypertensive medication.
In people without ADL limitation, increasing DBP was also associated with higher CVD risk, although the relationship lost significance after accounting for confounders.
These data “support the notion that lowering of SBP is beneficial in nonfrail elders and question the need for higher targets in this population”, say Peralta et al.
By contrast, among people with ADL limitation, higher DBP conferred a lower CVD risk, with each 10 mmHg increase associated with about a 15% risk reduction. Relative to a DBP of 65 mmHg or lower, CVD risk fell by 35% at a DBP of 66 to 80 mmHg and by 51% at a DBP above 80 mmHg.
“[A]mong people with limitation in ADL, the benefit of a lower SBP may need to be weighed against the associations of diastolic hypotension with higher risk of CVD and death”, concludes the team in Hypertension.
“Future research is necessary to determine benefits and harms of lowering each BP component in frail adults and the role of vascular stiffness in explaining these observations.”
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