Feasibility of clinical trial recruitment for cerebral amyloid angiopathy: A specialist single centre experience

Cerebrospinal fluid metallomics in cerebral amyloid angiopathy: an exploratory analysis

Introduction

Cerebral amyloid angiopathy (CAA) is associated with symptomatic intracerebral haemorrhage. Biomarkers of clinically silent bleeding events, such as cerebrospinal fluid (CSF) ferritin and iron, might provide novel measures of disease presence and severity.

Methods

We performed an exploratory study comparing CSF iron, ferritin, and other metal levels in patients with CAA, control subjects (CS) and patients with Alzheimer’s disease (AD). Ferritin was measured using a latex fixation test; metal analyses were performed using inductively coupled plasma mass spectrometry.

Results

CAA patients (n = 10) had higher levels of CSF iron than the AD (n = 20) and CS (n = 10) groups (medians 23.42, 15.48 and 17.71 μg/L, respectively, p = 0.0015); the difference between CAA and AD groups was significant in unadjusted and age-adjusted analyses. We observed a difference in CSF ferritin (medians 10.10, 7.77 and 8.01 ng/ml, for CAA, AD and CS groups, respectively, p = 0.01); the difference between the CAA and AD groups was significant in unadjusted, but not age-adjusted, analyses. We also observed differences between the CAA and AD groups in CSF nickel and cobalt (unadjusted analyses).

Conclusions

In this exploratory study, we provide preliminary evidence for a distinct CSF metallomic profile in patients with CAA. Replication and validation of these results in larger cohorts is needed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10711-6.

Cerebrospinal Fluid Biomarkers in Cerebral Amyloid Angiopathy

Background:

There is limited data on cerebrospinal fluid (CSF) biomarkers in sporadic amyloid-β (Aβ) cerebral amyloid angiopathy (CAA).

Objective:

To determine the profile of biomarkers relevant to neurodegenerative disease in the CSF of patients with CAA.

Methods:

We performed a detailed comparison of CSF markers, comparing patients with CAA, Alzheimer’s disease (AD), and control (CS) participants, recruited from the Biomarkers and Outcomes in CAA (BOCAA) study, and a Specialist Cognitive Disorders Service.

Results:

We included 10 CAA, 20 AD, and 10 CS participants (mean age 68.6, 62.5, and 62.2 years, respectively). In unadjusted analyses, CAA patients had a distinctive CSF biomarker profile, with significantly lower (p < 0.01) median concentrations of Aβ₃₈, Aβ₄₀, Aβ₄₂, sAβPPα, and sAβPPβ. CAA patients had higher levels of neurofilament light (NFL) than the CS group (p < 0.01), but there were no significant differences in CSF total tau, phospho-tau, soluble TREM2 (sTREM2), or neurogranin concentrations. AD patients had higher total tau, phospho-tau and neurogranin than CS and CAA groups. In age-adjusted analyses, differences for the CAA group remained for Aβ₃₈, Aβ₄₀, Aβ₄₂, and sAβPPβ. Comparing CAA patients with amyloid-PET positive (n = 5) and negative (n = 5) scans, PET positive individuals had lower (p < 0.05) concentrations of CSF Aβ₄₂, and higher total tau, phospho-tau, NFL, and neurogranin concentrations, consistent with an “AD-like” profile.

Conclusion:

CAA has a characteristic biomarker profile, suggestive of a global, rather than selective, accumulation of amyloid species; we also provide evidence of different phenotypes according to amyloid-PET positivity. Further replication and validation of these preliminary findings in larger cohorts is needed.

Guidelines for Evaluating the Feasibility of Recruitment in Pilot Studies of Diverse Populations: An Overlooked but Important Component

Background

In health disparities research, studies often fall short of their recruitment goals. Conducting a pilot feasibility study of recruitment in which data are collected systematically on recruitment processes can help investigators refine methods for the larger study. However, there are few guidelines for conducting pilot feasibility studies, and recruitment methods are seldom the focus. Feasibility indicators differ from traditional reports of recruitment results by focusing on the extent to which recruitment goals are met.

Methods

We present an organizing framework for assessing the feasibility of recruitment that includes eight steps, briefly: 1) specify recruitment goals; 2) specify recruitment processes; 3) establish a tracking system for each individual; 4) establish a tracking database for monitoring processes and results; 5) implement recruitment and track each individual's progress; 6) summarize recruitment results; 7) calculate and interpret feasibility measures - were goals met; and 8) if goals were not met, utilize tracking data to modify methods for the larger study. We describe methods within each step, with added details for steps 2-5 (the specific processes). The framework draws from a small literature on recruitment feasibility with a focus on health disparities populations. The guidelines blend well-known methods of recruitment with additional information on calculating feasibility indicators.

Conclusions

These guidelines provide a first step in thinking systematically about recruitment feasibility, to advance the field of measuring feasibility. Feasibility indicators also can be used to track the effectiveness of innovative recruitment strategies as part of building the science of recruitment, especially in disparities populations.