Frailty and cardiovascular disease: A two-way street?
CAN RISK BE MODIFIED IN FRAIL ADULTS?
Orkaby et al4 nicely lay out the guidelines for standard cardiovascular risk factor modification viewed in light of what is currently known—or not known—about how these recommendations should be interpreted for the older, frail, at-risk population. It is important to note at the outset that clinical trial data both inclusive of this population and incorporating the up-front assessment of frailty to predefine frail-or-not subgroups are sparse, and thereby evidence for how to optimize cardiovascular disease prevention in this important cohort is largely based on smaller observational studies and expert consensus.
Hypertension
However, important subanalyses derived from 2 large randomized controlled trials (Hypertension in the Very Elderly Trial [HYVET] and Systolic Blood Pressure Intervention Trial [SPRINT]) looking specifically at the impact of frail status on blood pressure treatment targets and related outcomes in elderly adults have recently been published.8,9 Notably, both studies showed the beneficial outcomes of more intensive treatment (to 150/80 mm Hg or 120 mm Hg systolic, respectively) persisted in those characterized as frail (via Rockwood frailty index or slow gait speed).8,9 Importantly, in the SPRINT analysis, higher event rates were seen with increasing frailty in both treatment groups; across each frailty stratum, absolute event rates were lower for the intensive treatment arm.9 These results were evident without a significant difference in the overall rate of serious adverse events9 or withdrawal rates8 between treatment groups.
Hypertension is the primary domain in which up-to-date clinical trial data have shown benefit for continued aggressive treatment for cardiovascular disease prevention regardless of the presence of frailty. Despite these data, in the real world, the “eyeball” frailty test often leads us to err on the side of caution regarding blood pressure management in the frail older adult. Certainly, the use of antihypertensive therapy in this population requires balanced consideration of the risk for adverse effects; the SPRINT analysis also found higher absolute rates of hypotension, falls, and acute kidney injury in the more intensively treated group.9 These adverse effects may be ameliorated not necessarily by modifying the target goal that is required, but by employing alternative strategies in achieving this goal, such as starting with lower doses, uptitrating more slowly, and monitoring with more frequent laboratory testing.
Currently, consensus guidelines in Canada have recommended liberalizing blood pressure treatment goals in those with “advanced frailty” associated with a shorter life expectancy.10
Dyslipidemia
Regarding the other major vascular risk factors, trials looking at the role of frailty in the targeted treatment of hyperlipidemia with statins in older patients for primary prevention of cardiovascular disease are lacking, although the Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) trial showed a significant positive benefit for statin therapy in adults over age 70 (number needed to treat of 19 to prevent 1 major cardiovascular event, and 29 to prevent 1 cardiovascular death).11 This again may be counterbalanced by the purported increased risk of cognitive and potential adverse functional effects of statins in this age group; however, trial data specific to frail status or not is required to truly assess the benefit-risk ratio in this population.
Hyperglycemia
Meanwhile, recent clinical trials looking at the impact of age, functional impairment, and burden of comorbidities (rather than specific frailty measures) on glucose-lowering targets and cardiovascular outcomes have failed to show a benefit from intensive glycemic control strategies, leading guideline societies to endorse less-stringent hemoglobin A1c goals in this population.12 Given the well-documented association between hyperglycemia and cardiovascular disease, as well as the purported dysregulated glucose metabolism underlying the frail phenotype, it is important that future trials looking at optimal hemoglobin A1c targets incorporate the presence or absence of frailty to better inform specific recommendations for this population.
ONE SIZE MAY NOT FIT ALL
Overall, if both prefrailty and frailty are independent risk factors for, and a consequence of, clinical cardiovascular disease, it is worth bearing in mind that the modification of “intensive” or best practice therapies based on qualitatively assessed frailty may actually contribute to the problem. With best intentions, the negative impact of frailty on cardiovascular outcomes may be augmented by automatically assuming it to reflect a need for “therapy-light.” The adverse downstream consequences of inadequately treated cardiovascular risk factors are not in doubt, and it is important as the role of frailty becomes an increasingly recognized cofactor in the management of older adults with these risk factors that the vicious cycle underlying both syndromes is kept in mind, in order to avoid frailty becoming a harbinger of undertreatment in older, geriatric populations.
What is clear is that more prospective clinical trial data in this population are urgently needed in order to better delineate the exact interactions between frail status and these risk factors and the potential downstream consequences, using prespecified and robust frailty assessment methods.
Perhaps frailty should be seen as a series of stages rather than simply as a binary “there or not there” biomarker; through initial and established stages of the syndrome, which have been independently associated with both clinical events and subclinical surrogates of cardiovascular disease, risk factors should continue to be treated aggressively and according to best available evidence. However, as guideline societies are already beginning to endorse as highlighted above, once the phenotype becomes tethered with a certain threshold burden of comorbidity, cognitive or functional impairment, or more end-stage disease status, then goals for cardiovascular disease prevention may need to be readdressed and modified. If frailty is truly confirmed as a cardiovascular disease equivalent, not only appropriately treating associated cardiovascular risk factors but also seeking therapies that actively target the frailty syndrome itself should be an important goal of future studies seeking to impact the development of both clinical and subclinical cardiovascular disease in this population.
