Updates in Aspirin Use, Aducanumab, and CKD Diagnosis in Geriatric Care

Mengru Wang, MD, MPH

Disclosures

June 30, 2022

This article originally appeared on MDedge.com.

The following highlights are a brief overview of guideline updates, drug approvals, and diagnostics relevant to geriatric medicine from June 2021 to April 2022, some of which were discussed at the American Geriatrics Society conference in May. I selected these topics as they were among the most discussed by my colleagues in geriatric medicine and inquired about by my primary care patients in geriatric medicine clinic. I hope that these updates provide primary care clinicians who care for older adults with more context and background information regarding new Alzheimer’s disease therapy to better answer patient inquiries, and to feel empowered to deprescribe aspirin and reframe the diagnostic criteria of chronic kidney disease (CKD).

Aspirin for primary prevention

Mengru Wang, MD, MPH

It was welcome news in the geriatrics community when the United States Preventive Services Task Force updated their guidelines in April 2022 to recommend against the initiation of aspirin for primary prevention in adults aged 60 or older. This recommendation was based on studies that found that net benefits of CVD prevention in older adults are outweighed by risk of bleeding.[1]

The risk of bleeding increases with age and can occur in individuals without common risk factors for bleeding, such as prior gastrointestinal bleeding, peptic ulcer disease, concurrent NSAID use, or corticosteroid use.

While it may be easier to not initiate aspirin for primary prevention, deprescribing aspirin for patients who have been on aspirin long term for primary prevention presents more of a challenge. Modeling data from the USPTSF suggest stopping aspirin at age 75 for those taking aspirin for primary prevention.[2]

Behavioral change, particularly for patients who have been on aspirin for decades, can be difficult. A 2021 study by Green et al. found that language that resonates the most with older adults when deprescribing emphasized the side effects rather than statements such as “this will not help you” or “do not need anymore.”[3]

Aducanumab for mild cognitive impairment and mild Alzheimer’s dementia

One of the most discussed topics this past year is the Food and Drug Administration approval of aducanumab (brand name Aduhelm) in June 2021. Aducanumab is the first approved disease-modifying therapy for Alzheimer’s disease and the first drug approved for the treatment of Alzheimer’s disease since 2003. Aducanumab is an antiamyloid monoclonal antibody that was developed to reduce amyloid plaque in the brain, one of the features of Alzheimer’s disease pathology.

Uptake of aducanumab by dementia providers has been limited for several reasons. Firstly, the clinical significance of the drug remains in question. ENGAGE and EMERGE were the two main randomized clinical trials that studied the effect of aducanumab on amyloid burden and clinical stages of dementia over 18 months. While both studies demonstrated that aducanumab reduced amyloid burden based on neuroimaging and in cerebrospinal fluid, the ENGAGE trial found no difference in the stage of dementia. The EMERGE trial did note a small, statistically significant difference in stage of dementia, however the participants of the EMERGE trial had a faster rate of progression of dementia than the placebo participants in the ENGAGE trial, which could have contributed to the difference detected.[4]

Additionally, exclusion criteria for both trials call into question the generalizability of this study. Participants over age 85, with CKD, prior stroke, or transient ischemic attacks, or on anticoagulation were excluded. One of the drivers for the exclusion criteria is the increased risk of macro and microhemorrhages.

Thirty-five percent of research participants were incidentally noted to have brain edema, an abnormality called amyloid-related imaging abnormality or ARIA-E, that necessitated serial monitoring with brain MRIs. It is also important to highlight that inclusion of African American, Hispanic, and Latinx participants in these studies was less than 5%, despite a higher incidence of Alzheimer’s disease in these populations.[5]

Lastly, economic implications for the U.S. health care system with increased uptake of aducanumab could be enormous. Originally quoted at $56,000 yearly, Biogen, the maker of aducanumab, recently reduced annual costs to $28,200 per patient.

In April 2022, CMS released a statement that antiamyloid monoclonal antibodies and related services, including PET scans, would be covered under Medicare for those with mild cognitive impairment and mild Alzheimer’s dementia with confirmed presence of amyloid. A study by Mafi et al. estimated that aducanumab could cost Medicare between $7 billion and $37.4 billion annually based on lower and upper bound estimates of eligible Medicare beneficiaries.[6]

Overdiagnosis of CKD in older adults

The current diagnostic criteria of CKD, which is based on an estimated glomerular filtration rate (eGFR) of less than 60, has been up for debate, as glomerular filtration rate (GFR) physiologically decreases with age. Fixed thresholds can lead to underdiagnosis of CKD in younger adults and overdiagnosis of CKD in older adults. Age-adapted thresholds for the diagnosis of CKD have been proposed, with the suggestion of an eGFR threshold of 45mL/min/1.73 m2 for adults aged 65 and older.[7]

The clinical implication of using an age-adapted eGFR threshold definition was investigated in a 2021 cohort study by Liu et al.[8] In this study, outcomes of adults diagnosed with CKD using a fixed threshold versus age-adapted threshold were compared with a healthy cohort.

A fixed threshold led to a 60% higher incidence of CKD diagnosis. However, incidence of renal failure and all-cause mortality in older adults with an eGFR between 45-59 /min/1.73 m2 with normal or mild albuminuria was of similar magnitude to the healthy cohort at 5 years of follow-up.

These findings support the use of age-adapted thresholds for the diagnosis of CKD in older adults, as an earlier diagnosis of mild CKD does not equate to clinical benefits, but could lead to harms of unnecessary interventions and patient anxiety.

Dr Mengru "Ruru" Wang is a geriatrician and internist at the University of Washington, Seattle. She practices full-spectrum medicine, seeing patients in primary care, nursing homes, and acute care.

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