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Cascade testing effectively identifies undiagnosed sickle cell disease in The Gambia: a quality improvement project
Etienne Deans-Louis1, Angela Allen2, Stephen John Allen3,2
1Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK.
Insights
Cascade testing effectively identified sickle cell disease (SCD) and carriers in The Gambia. This approach, using point-of-care tests, is feasible for early SCD detection and improved outcomes in low-resource settings.
Area of Science:
- Hematology
- Public Health
- Genetics
Background:
- Sickle cell disease (SCD) poses a significant mortality risk in childhood in low and middle-income countries (LMICs).
- Newborn screening for SCD is not widely established in LMICs, hindering early diagnosis and intervention.
- Cascade testing presents a potential strategy to identify individuals with SCD and sickle cell trait.
Purpose of the Study:
- To evaluate the feasibility and effectiveness of cascade testing for identifying undiagnosed SCD and haemoglobin (Hb) S carriers in LMICs.
- To assess the utility of point-of-care testing in routine care settings for SCD detection.
Main Methods:
- A quality improvement project was conducted at the Haematology Clinic, Edward Francis Small Teaching Hospital, Banjul, The Gambia.
- Hb phenotype was determined for siblings of SCD index cases using the HemoTypeSC test and confirmed by Hb electrophoresis.
- The study focused on identifying undiagnosed SCD cases within families.
Main Results:
- Out of 102 invited families, 31 (30%) participated, with 53 siblings tested.
- Cascade testing identified 10 siblings (19%) with HbSS (SCD), 25 (47%) as HbAS carriers, and 18 (34%) as HbAA (unaffected).
- HemoTypeSC test results showed high agreement with Hb electrophoresis.
Conclusions:
- Cascade testing is an effective method for identifying individuals with SCD and those carrying the sickle cell gene.
- Facilitated by point-of-care tests, cascade testing is feasible and affordable for increasing SCD detection and improving outcomes in LMICs.
- Early diagnosis through cascade testing can significantly improve patient outcomes in resource-limited settings.
Objective:
Sickle cell disease (SCD) has a high mortality during childhood in many low and middle-income countries (LMICs). Early diagnosis improves outcomes but newborn screening is not well established in LMICs. Cascade testing may be feasible and effective in identifying undiagnosed SCD and carriers of haemoglobin (Hb) S.
Design:
Quality improvement project using existing clinic and laboratory resources.
Setting:
The Haematology Clinic at the Edward Francis Small Teaching Hospital, Banjul, The Gambia.
Participants:
Families of index cases with SCD.
Methods:
Hb phenotype was determined in full or half-siblings of a SCD index case over a 6-week period using the HemoTypeSC test and confirmed by Hb electrophoresis.
Main Outcome Measure:
Identifying undiagnosed SCD.
Results:
Of 102 families invited, 31 (30%) attended during the study period and 53 siblings were tested. Except for one indeterminate test, HemoType SC agreed with Hb electrophoresis. Ten (19%; 95% CI 10 to 32) siblings were diagnosed with HbSS, 25 (47%; 34 to 60) as carriers (HbAS) and 18 (34%; 23 to 48) were unaffected (HbAA). Some symptoms and signs of SCD occurred significantly more frequently in HbSS than in HbAA and HbAS, but none was sufficiently common to help in identifying children for testing.
Conclusions:
Cascade testing was effective in identifying undiagnosed HbSS as well as children carrying the sickle cell gene. In routine care settings in LMICs, cascade testing facilitated by point-of-care tests may be feasible and affordable in increasing the detection of SCD and improving outcomes through earlier diagnosis.
