Sickle Cell Data Collection Program Report: Data to Action – Gaps in Knowledge

Research has shown a great need for SCD data collection and analysis: 1 of the 5 recommendations of the 2007 American Society of Pediatric Hematology/Oncology Sickle Cell Summit was to use population-based surveillance (identifying all new cases of disease through monitoring of a defined population or group) to measure changes in health called ‘health outcomes’.¹¹ The following year, the National Institutes of Health convened a State-of-the-Science Conference. An identified need from that conference was

“a surveillance system … for patients with sickle cell disease who will be followed prospectively [their health will be monitored into the future]. This system should contain demographic [such as sex, education level, income level, marital status, etc], laboratory, clinical, treatment, and outcome information.”

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Although SCD is the most common inherited blood disorder in the United States, remarkably little is known about people affected by SCD. The SCDC program aims to address gaps in knowledge about SCD including the ones below.

How many people live with SCD?

Centers for Disease Control and Prevention (CDC) estimates that SCD affects more than 100,000 people in the United States, but the exact number of people with SCD is unknown because no national data collection system exists for the disease. The estimated number of people affected by SCD is often based on newborn screening and life expectancy data (taken from other data).

In the United States, there are data systems for specific diseases, such as the National Program of Cancer Registries; however, there is no similar system for SCD, which could determine the actual or true number of people living with SCD and how SCD affects their health.

An incomplete picture of SCD

Much of the currently available SCD research relies on one of two sources of data: clinical data (data collected for research purposes such as data from electronic health records) or administrative data (data collected for recordkeeping rather than research purposes). Clinical data includes reporting only on patients who seek care at SCD clinics (clinical care centers that specialize in care for people with SCD) but many patients, especially adults, with SCD do not have access to a SCD clinic and must receive care elsewhere such as the emergency department (ED). Therefore, research based on clinical data alone likely excludes a large number of people with SCD.

Administrative data, such as hospital discharge or state Medicaid data may include inaccurate reporting of SCD and related issues because the records may include patients who were miscoded or not coded for SCD. Research suggests that administrative data alone are unreliable because they may dramatically overestimate the number of people with SCD (by including patients who were miscoded for SCD) and thereby underestimate the use of healthcare services by true cases of SCD.¹³

Although SCD is the most common inherited blood disorder in the United States, remarkably little is known about people affected by SCD.

Limited information about the course of disease

In the United States, all states have had universal screening for SCD since 2006 as part of state administered newborn screening programs. However, little is known about what happens to these infants after the positive screening results are shared with the family and pediatrician. More SCD research is needed to better understand patterns around their

• Use of healthcare services (location of care and use of outpatient, emergency department, and hospital services)
• Uptake of recommended treatments (transcranial Doppler screening, transfusions, hydroxyurea, penicillin, immunizations)
• Healthcare outcomes (coexisting or co-occurring conditions, surgeries, stroke, death).

Beginning in the later teen years and into adulthood, patients often suffer from more frequent SCD-related complications than younger pediatric patients.¹⁴ These complications include pain crises, chronic pain, and avascular necrosis (death of bone tissue due to a lack of blood supply). ¹⁴ The increase in complications during this time is likely due in part to a lack of access to proper care during transition from pediatric to adult care.¹⁵ More research is needed to gain a better understanding of the complex health needs of patients as they undergo this change or transition in care.

In addition, few studies have been carried out on older patients with SCD. Advancements in treatment and health care have extended life expectancy and changed the disease course for people with SCD. Recently, there has been enough people with SCD to study into older age. Consequently, little has been published about complications, coexisting (2 or more conditions the patient has at the same time) or co-occurring conditions (presence of both a mental health and a substance-use disorder), and the use of healthcare services among patients over the age of 45.