source: American Society of Hematology

year: 2017

authors: Michael U. Callaghan, Patrick C. Hines, Debra D Pittman, David Beidler, Denis Rybin, Ahmar Urooj Zaidi, Jennell White, Ke Liu, Bryan Hannan, Xiufeng Gao, Andreas M Pleil, Alexandra Barsdorf, Martin David, Melanie Simmons, Andrew L Frelinger III, Alan D Michelson, Nick Clarke, Robert J Charnigo

Clinical trials in sickle cell disease (SCD) continue to have challenges achieving clinical endpoints. Most SCD clinical trials have focused on painful vaso-occlusive crisis (VOC) episodes because they are prevalent, debilitating and often lead to medical contact. However with VOC as a clinical endpoint: there are no objective, quantifiable biomarkers of pain; pain may not be specific to VOC; the threshold for medical contact varies between patients; VOCs occurring at home without medical contact are not captured; other components of VOC (e.g., fatigue, functioning) are poorly assessed. We therefore undertook the present non-interventional, longitudinal study to test novel tools for the identification of VOCs occurring in SCD patients with varying degrees of medical contact.

During 6 months of evaluation, longitudinal measures of pain, fatigue, function, activity (by actigraphy), clinical laboratory and biomarker samples from SCD patients (+/- hydroxyurea therapy) in steady state to VOC were studied. A novel electronic patient-reported outcome tool (ePRO) enabled patients to self-report daily pain, fatigue, function, and medication use. It was also used to report VOC in real time, triggering an alert to a mobile phlebotomy team. Blood collections were taken within 24 and 48 hours of self-reported VOC onset (either at home, emergency department [ED], or hospital). Follow-up blood samples were collected 2 days after resolution of the VOC. Baseline blood samples were drawn at home every 3 weeks during stable, non-VOC periods. Biomarker assays included leukocyte-platelet aggregates and circulating microparticles measured by flow cytometry, cell adhesion in microfluidic flow-based assays to immobilized vascular cell adhesion molecule or P-selectin, and a panel of soluble adhesion molecules, cytokines, inflammatory mediators and coagulation factors. Patients wore a Phillips Actiwatch Spectrum™ actigraphy device to track sleep and activity. Patient-reported outcomes, activity, and biomarkers on non-VOC days were compared to those on VOC days using a mixed model approach and results are reported as means with 95% confidence intervals (95%CI).

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