Jo Howard, April E. Slee, Simon Skene, Baba Inusa, Jamie Kawadler, Michelle Downes, Johanna Gavlak, Melanie Koelbel, Hanne Stotesbury, Maria Chorozoglou, Susan Tebbs, Subarna Chakravorty, Moji Awogbade, David C. Rees, Atul Gupta, Patrick B. Murphy, Nicholas Hart, Sati Sahota, Carol Nwosu, Maureen Gwam, Dawn Saunders, Vivek Muthurangu, Nathaniel Barber, Emmanuel Ako, Swee Lay Thein, Melanie Marshall, Isabel C Reading, Man Ying Edith Cheng, Fenella J. Kirkham, Christina Liossi

In addition to pain, sickle cell anaemia (HbSS) complications include neurocognitive difficulties in attention and processing speed associated with low daytime and night-time oxygen saturation compounded by obstructive sleep apnoea (OSA). In the general population OSA is treated with continuous positive airways pressure (CPAP). The aim of this single-blind, randomised, controlled phase II trial is to compare auto-adjusting CPAP (APAP) with standard care to standard care alone in individuals with HbSS to determine whether the intervention improves attention and processing speed, brain structure, pain and quality of life. Eligibility criteria include: ability to provide informed consent; age > 8 years; diagnosis of HbSS; and mean overnight saturation of < 90% for < 30% of the night (i.e. not meeting current criteria for overnight oxygen therapy). Key exclusion criteria are: overnight respiratory support; respiratory or decompensated cardiac failure; chronic transfusion; or contraindications to APAP therapy or magnetic resonance imaging (MRI). Sixty individuals with HbSS (30 children and 30 adults) will be randomised to standard care + APAP or standard care alone for six months. Minimisation factors are: age group (8-11, 12-15, 16-22 and > 23 years); silent infarction on MRI; minimum overnight oxygen saturation > 90% or < 90%; and hydroxyurea use. For APAP individuals, the intervention is administered at home. Adherence and effectiveness are recorded using software documenting hours of use each night and overnight oximetry. Participant support in terms of appropriate facemask and facilitating adherence are provided by an unblinded sleep physiologist. The primary outcome is change in the cancellation subtest from the Wechsler scales. Secondary outcomes include general cognitive functioning, quantitative brain MRI, blood and urine chemistry, quality of life and daily pain via a smartphone App (GoMedSolutions, Inc) and, where possible MRI heart, echocardiography, and 6-min walk. These outcomes will be assessed at baseline and after six months of treatment by assessors blind to treatment assignment. Altering oxygen saturation in HbSS may lead to bone marrow suppression. This risk will be reduced by monitoring full blood counts at baseline, two weeks, three months and six months, providing treatment as appropriate and reporting as safety events. ISRCTN46012373 . Registered on 10 July 2015. Protocol Version: 6.0 Date: 24th December 2015 Sponsor: University Hospital Southampton. Sponsor's protocol code: RHMCHIOT53.