Sickle cell disease is the name of a group of lifelong conditions that inhibits blood flow to parts of the body due to clotting of the blood (1). In 2016, around 14’000 patients with this disease lived in the UK (2); this number is expected to increase due to immigration into the UK (black people are affected more) (3). A severe complication of sickle cell disease is stroke, a condition in which parts of the brain stop functioning properly due to lack of blood flow or due to bleeding. Stroke is associated with a high risk of death or disability (4,5). Up to 10% of children and young adults with sickle cell disease may develop stroke (6). Over the past decade, advances in the detection of and therapy for sickle cell disease have been made. This has resulted in an increase in the number of children with sickle cell disease surviving into adulthood, partly by decreasing the risk of stroke in childhood and adolescence (5,7).
The goal of this study is to describe patients with sickle cell disease in the UK between 1991 and 2020 with respect to type of sickle cell disease, percentage who experienced stroke, stroke type, age at stroke diagnosis, and distribution of stroke occurrence between women/girls and men/boys. Moreover, we plan to investigate the risk of stroke in children and young adults overall and by birth period (prior to or after the establishment of new born screening in the UK).
Sickle cell disease (SCD) defines a group of inherited conditions that affect haemoglobin (1). SCD leads to many complications, amongst others the occlusion of blood vessels including large cerebral arteries (7–9). The incidence of stroke in patients with SCD is much higher than in patients without SCD. The cumulative incidence of stroke (including ischaemic or haemorrhagic stroke, transient ischaemic attack) ranges from 1-11% (depending on whether or not screening and blood transfusions are employed) (10) in childhood and was estimated to be 24% up to the age of 45 years (11,12). Haemorrhagic stroke is estimated to occur in 3% of children and 10% of adults with SCD (13).
In 2016, approximately 14,000 patients with SCD lived in the UK (2). Use of new born screening for SCD was fully established in the UK in 2006 (14) and is conducted within the first year of life; it identifies SCD in about 1 in 2000 newborns (2,7,15). Today, the percentage of children with SCD reaching adulthood in high-income countries is as high as that of children without SCD, which in turn increases the number of patients with SCD at risk of stroke in adulthood (5,7).
The goal of this study is to describe patients with a diagnosis of SCD in CPRD GOLD with respect to subtype of SCD (sickle cell anaemia, double heterozygous sickling disorders or other sickle cell disorders), and percentage who experienced a first stroke by age, sex, and stroke subtype (ischaemic stroke, haemorrhagic stroke or transient ischaemic attack). We also plan to estimate incidence rates of stroke overall and stratified by birth period (prior to the establishment of new born screening [1991-2005] or after [2006 to 2020]), among a sub-cohort of children with SCD who started contributing data to the CPRD GOLD in their first year of life.
Stroke (including ischaemic stroke; haemorrhagic stroke; transient ischaemic attack; unspecified stroke) defined as a stroke Read code recorded in the CPRD GOLD and/or a stroke ICD-10 code in HES APC data.
Susan Jick - Chief Investigator - BCDSP - Boston Collaborative Drug Surveillance Program
Marlene Rauch - Corresponding Applicant - University of Basel
Christoph Meier - Collaborator - University of Basel
Deniz Kadioglu - Collaborator - University of Basel
Christoph Meier - Collaborator - University of Basel
HES Admitted Patient Care