Concordance between the updated Elecsys cerebrospinal fluid immunoassays and amyloid positron emission tomography for Alzheimer's disease assessment: findings from the Apollo study.

Objectives: The Apollo study was designed to support the clinical performance verification of the adjusted cutoffs of the Elecsys β-Amyloid(1-42) (Aβ) cerebrospinal fluid (CSF) II, β-Amyloid(1-40) (Aβ) CSF, Phospho-Tau (181P) (pTau) CSF and Total-Tau (tTau) CSF immunoassays (Roche Diagnostics International Ltd) for measuring fresh CSF samples, and assess the concordance of the Elecsys CSF pTau/Aβ, tTau/Aβ and Aβ/Aβ ratios, as well as Aβ alone, with amyloid positron emission tomography (PET) visual read status.

Methods: The primary study endpoint was to assess the concordance of the Elecsys CSF ratios and Aβ alone with amyloid PET visual read status using fresh CSF samples collected from individuals with subjective cognitive decline or mild cognitive impairment, handled with a new routine-use pre-analytical procedure and measured with the Elecsys CSF immunoassays. The sample stability after 1- to 13-week storage at -20 °C was also investigated in an exploratory analysis.

A qualitative study examining the validity and comprehensibility of physical activity items: developed and tested in children with juvenile idiopathic arthritis.

Background: Not all physical activity (PA) questionnaires (PAQ) gather information regarding PA intensity, duration, and modes and only a few were developed specifically for children. We assessed children's comprehensibility of items derived from two published PAQs used in children along with three items designed to ascertain PA intensity in order to assess comprehensibility of items and identify response errors. We modified items to create a new PAQ for children (ASCeND).