Decision making in clinical trials: Interim analyses, innovative design, and biomarkers

The efficient and accurate execution of clinical trials testing novel treatments for Alzheimer's disease (AD) is a critical component of the field's collective efforts to develop effective disease-modifying treatments for AD. The lengthy and heterogeneous nature of clinical progression in AD contributes to the challenges inherent in demonstrating a clinically meaningful benefit of any potential new AD therapy. The failure of many large and expensive clinical trials to date has prompted a focus on optimizing all aspects of decision making, to not only expedite the development of new treatments, but also maximize the value of the information that each clinical trial yields, so that all future clinical trials (including those that are negative) will contribute toward advancing the field. To address this important topic the Alzheimer's Association Research Roundtable convened December 1-2, 2020. The goals focused around identifying new directions and actionable steps to enhance clinical trial decision making in planned future studies.

EXERT: Impact of COVID‐19 on retention and intervention delivery of a large multisite exercise trial in adults with MCI

Background

EXERT, a multisite 18‐month RCT, is testing the effects of aerobic exercise vs. stretching on cognition and AD biomarkers in sedentary adults with MCI. In the first 12 months, participant exercise 2x/week under the supervision of YMCA trainers, and 2x/week on their own. In months 13‐18, participants continue to exercise 4x/week but without supervision. Here we describe the impact of the COVID‐19 pandemic on delivery of this support‐intensive intervention that involved many challenges but also opportunities for innovation.

Method

In February 2020, EXERT met the recruitment goal with 296 enrolled. In March 2020 when COVID‐19 incidence rates began to climb in the US, study assessments and per‐protocol intervention delivery were paused. During the pause, all YMCAs were closed, and the majority of study‐certified YMCA trainers were furloughed.

Result

At the time of the pause (March 23), 153 participants were in the supervised phase of the study, and 65 participants were in the unsupervised phase. To keep participants engaged and encourage adherence to the intervention, sites initiated weekly calls with active participants to provide support, address barriers to exercise and collect self‐report adherence data. By September, 7 of 14 sites resumed study activities. Weekly call completion rates during the pause exceeded 85%, and participants reported completing a mean of 3.3 40‐minute exercise sessions per week. On these calls, participants frequently expressed gratitude for the regular contact. By February 2021, all sites resumed activities despite COVID infection rates that have continued to climb across the US. In response, supervised exercise for the majority of participants was transitioned from in‐person to web‐conferencing. Even with this change that can be challenging for MCI, supervised session adherence rates are 72% for the aerobic group and 79% for the stretching group. Retention has remained high at 87%.

Conclusion

The COVID‐19 pandemic presented unprecedented challenges, but it also provided unique opportunities to adapt intervention delivery so that a community‐based exercise trial could continue – even during a debilitating global health crisis. EXERT’s adaptations may ultimately impact resilience of the intervention to even the most challenging of circumstances that older adults with MCI will face now and in the future.

Recruitment of a multi-site randomized controlled trial of aerobic exercise for older adults with amnestic mild cognitive impairment: The EXERT trial

INTRODUCTION

Effective strategies to recruit older adults with mild cognitive impairment (MCI) into nonpharmacological intervention trials are lacking.

METHODS

Recruitment for EXERT, a multisite randomized controlled 18-month trial examining the effects of aerobic exercise on cognitive trajectory in adults with amnestic MCI, involved a diverse portfolio of strategies to enroll 296 participants.

RESULTS

Recruitment occurred September 2016 through March 2020 and was initially slow. After mass mailings of 490,323 age- and geo-targeted infographic postcards and brochures, recruitment rates increased substantially, peaking at 16 randomizations/month in early 2020. Mass mailings accounted for 52% of randomized participants, whereas 25% were recruited from memory clinic rosters, electronic health records, and national and local registries. Other sources included news broadcasts, public service announcements (PSA), local advertising, and community presentations.

DISCUSSION

Age- and geo-targeted mass mailing of infographic materials was the most effective approach in recruiting older adults with amnestic MCI into an 18-month exercise trial.

Differentiating among stages of cognitive impairment in aging: Version 3 of the Uniform Data Set (UDS) neuropsychological test battery and MoCA index scores

INTRODUCTION

Federally funded Alzheimer's Disease Centers in the United States have been using a standardized neuropsychological test battery as part of the National Alzheimer's Coordinating Center Uniform Data Set (UDS) since 2005. Version 3 (V3) of the UDS replaced the previous version (V2) in 2015. We compared V2 and V3 neuropsychological tests with respect to their ability to distinguish among the Clinical Dementia Rating (CDR) global scores of 0, 0.5, and 1.

METHODS

First, we matched participants receiving V2 tests (V2 cohort) and V3 tests (V3 cohort) in their cognitive functions using tests common to both versions. Then, we compared receiver-operating characteristic (ROC) area under the curve in differentiating CDRs for the remaining tests.

RESULTS

Some V3 tests performed better than V2 tests in differentiating between CDR 0.5 and 0, but the improvement was limited to Caucasian participants.

DISCUSSION

Further efforts to improve the ability for early identification of cognitive decline among diverse racial groups are required.