Shared Care for Adults with Sickle Cell Disease: An Analysis of Care from Eight Health Systems

Stroke in sickle cell disease and the promise of recent disease modifying agents

Sickle cell disease (SCD) is an inherited hemoglobinopathy affecting approximately 100,000 individuals in the United States. Cerebrovascular disease is among the most common and debilitating complications of SCA, with 53% experiencing silent cerebral infarct by age 30 and 3.8% experiencing overt stroke by age 40 years. This review highlights the burden of cerebrovascular disease in SCD, including both stroke and silent cerebral infarct (SCI). We then discuss the pathophysiology of stroke and cerebral fat embolism in the absence of a patent foramen ovale. This review also reveals that options for primary and secondary stroke prevention in SCD are still limited to hydroxyurea and blood transfusion, and that the role of aspirin and anticoagulation in SCD stroke has not been adequately studied. Limited data suggest that the novel disease-modifying agents for SCD management may improve renal dysfunction, leg ulcers, and lower the abnormally high TCD flow velocity. Further research is urgently needed to investigate their role in stroke prevention in SCD, as these novel agents target the main stroke contributors in SCD - hemolysis and vaso-occlusion. This literature review also explores the role of healthcare disparities in slowing progress in SCD management and research in the United States, highlighting the need for more investment in patient and clinician education, SCD management, and research.

Sickle Cell Disease: A Review

IMPORTANCE

Sickle cell disease (SCD) is an inherited disorder of hemoglobin, characterized by formation of long chains of hemoglobin when deoxygenated within capillary beds, resulting in sickle-shaped red blood cells, progressive multiorgan damage, and increased mortality. An estimated 300 000 infants are born annually worldwide with SCD. Most individuals with SCD live in sub-Saharan Africa, India, the Mediterranean, and Middle East; approximately 100 000 individuals with SCD live in the US.

OBSERVATIONS

SCD is diagnosed through newborn screening programs, where available, or when patients present with unexplained severe atraumatic pain or normocytic anemia. In SCD, sickling and hemolysis of red blood cells result in vaso-occlusion with associated ischemia. SCD is characterized by repeated episodes of severe acute pain and acute chest syndrome, and by other complications including stroke, chronic pain, nephropathy, retinopathy, avascular necrosis, priapism, and leg ulcers. In the US, nearly all children with SCD survive to adulthood, but average life expectancy remains 20 years less than the general population, with higher mortality as individuals transition from pediatric to adult-focused health care systems. Until 2017, hydroxyurea, which increases fetal hemoglobin and reduces red blood cell sickling, was the only disease-modifying therapy available for SCD and remains first-line therapy for most individuals with SCD. Three additional therapies, L-glutamine, crizanlizumab, and voxelotor, have been approved as adjunctive or second-line agents. In clinical trials, L-glutamine reduced hospitalization rates by 33% and mean length of stay from 11 to 7 days compared with placebo. Crizanlizumab reduced pain crises from 2.98 to 1.63 per year compared with placebo. Voxelotor increased hemoglobin by at least 1 g/dL, significantly more than placebo (51% vs 7%). Hematopoietic stem cell transplant is the only curative therapy, but it is limited by donor availability, with best results seen in children with a matched sibling donor. While SCD is characterized by acute and chronic pain, patients are not more likely to develop addiction to pain medications than the general population.

CONCLUSIONS AND RELEVANCE

In the US, approximately 100 000 people have SCD, which is characterized by hemolytic anemia, acute and chronic pain, acute chest syndrome; increased incidence of stroke, nephropathy, and retinopathy; and a life span that is 20 years shorter than the general population. While hydroxyurea is first-line therapy for SCD, L-glutamine, crizanlizumab, and voxelotor have been approved in the US since 2017 as adjunctive or second-line treatments, and hematopoietic stem cell transplant with a matched sibling donor is now standard care for severe disease.

The OneFlorida Data Trust: a centralized, translational research data infrastructure of statewide scope

The OneFlorida Data Trust is a centralized research patient data repository created and managed by the OneFlorida Clinical Research Consortium ("OneFlorida"). It comprises structured electronic health record (EHR), administrative claims, tumor registry, death, and other data on 17.2 million individuals who received healthcare in Florida between January 2012 and the present. Ten healthcare systems in Miami, Orlando, Tampa, Jacksonville, Tallahassee, Gainesville, and rural areas of Florida contribute EHR data, covering the major metropolitan regions in Florida. Deduplication of patients is accomplished via privacy-preserving entity resolution (precision 0.97-0.99, recall 0.75), thereby linking patients' EHR, claims, and death data. Another unique feature is the establishment of mother-baby relationships via Florida vital statistics data. Research usage has been significant, including major studies launched in the National Patient-Centered Clinical Research Network ("PCORnet"), where OneFlorida is 1 of 9 clinical research networks. The Data Trust's robust, centralized, statewide data are a valuable and relatively unique research resource.

Awareness and Use of the Sickle Cell Disease Toolbox by Primary Care Providers in North Carolina

BACKGROUND

Sickle cell disease (SCD) is a complex chronic blood disorder characterized by severe disease complications ideally managed by both hematologists and primary care providers (PCP's). PCP's report knowledge gaps and discomfort with SCD management. Our team developed and a decision support tool for SCD management (SCD Toolbox) based on the National Heart, Lung, and Blood Institute's SCD guidelines. We surveyed PCPs in North Carolina (NC) prior to formal dissemination to determine current co-management practices, assess toolbox acceptability, use, format preferences, and understand which algorithms would be most helpful.

METHOD

A 23-item baseline needs assessment survey was disseminated to PCPs throughout NC.

RESULTS

A total of 63 medical providers responded to the survey and of these respondents, 64% reported caring for 1 to 10 patients with SCD. Only 39% of PCPs reported regular communication with an SCD specialist. Providers reported the highest level of awareness of the pediatric and adult health maintenance tools (41% and 39% respectively) and highest use of the pediatric (26%) and adult (28%) health maintenance tools. Respondents also expressed a desire to have access to multiple toolbox formats (37%) (website, mobile app and/or paper).

LIMITATIONS

The use of a convenience sample and low survey response are study limitations which hinder generalizability.

CONCLUSIONS

PCPs rarely co-managed with a specialist, had low awareness and use of SCD toolbox, and requested multiple formats for the toolbox.