Diagnostic Accuracy of HemotypeSC as a Point-of-Care Testing Device for Sickle Cell Disease: Findings from a Southwestern State in Nigeria and Implications for Patient Care in Resource-Poor Settings of sub-Saharan Africa

Determination of birth prevalence of sickle cell disease using point of care test HemotypeSC™ at Rundu Hospital, Namibia

BACKGROUND

Sickle cell disease (SCD), a noncommunicable disease, has the greatest burden in sub-Saharan Africa. The majority of children (50-90%) with SCD die before their 5th birthday, with approximately 150,000-300,000 annual SCD child deaths in Africa. In developed countries, newborn screening (NBS) has been shown to improve the survival of children with sickle cell disease, with under5 childhood mortality reduced tenfold due to interventions performed before the development of complications. Point -of-care tests have been developed for resource limited settings to expand NBS. The aim of this study was to determine the birth prevalence of sickle cell disease in Namibia using the HemoTypeSC™ point-of-care test.

METHODS

A cross-sectional descriptive study was carried out at Rundu Intermediate Hospital in the Kavango East Region. Two hundred and two (202) well newborns within 72 h of birth were recruited for the study from 22 February to the 23th March 2023. Descriptive statistics were used to compute the haemoglobin types of the study participants.

RESULTS

The majority of the participants (n = 105, 52%) were females, and (n = 97,48%) were males. The median age of the participants was 23 h (Q1, Q3; 11; 33),) with an age range of 2-98 h. Sickle cell trait was present in 9.4% of the screened newborns, no homozygous disease was detected, and 90.6% had Hb AA.

CONCLUSIONS

This study is the first to measure HbS gene carriage at birth using HemotypeSC point-of-care testing in Namibia. There was a moderate prevalence of sickle cell traits but no SCD. This baseline study may provide the foundation for larger epidemiological surveys to map HbS gene carriage in Namibia to provide evidence for policy makers to fashion appropriate SCD newborn screening services.

Newborn screening for sickle cell disease in Kisangani, Democratic Republic of the Congo: an update

BACKGROUND

Neonatal screening is the first action necessary to identify children with sickle cell disease (SCD) and thus ensure their care. Using rapid tests to give an immediate result to families is a new resilient approach of great interest. These two aspects are essential for establishing an adequate health policy for this disease. This study was undertaken in Kisangani to update the current incidence of neonatal SCD.

METHODS

Heel prick blood samples of 1432 babies born from different racial groups of parents living in Kisangani were collected at birth and screened using a point of care test, i.e. the HemoTypeSC^TM.

RESULTS

The incidence at birth was 2.2% (n = 31; 95% CI: [1.5%-3.1%]) for HbSS homozygosity and 21% (n = 303; 95% CI: [19%-23%]) for HbAS heterozygosity. Compared to a previous study in 2010; the incidence at the birth of the HbSS form has doubled, while that of the heterozygous form HbAS remained almost unchanged. The inter-ethnic incidence of HbSS among the five top-represented ethnic groups was significant (<0.001).

CONCLUSION

The prevalence of homozygote form has doubled compared to the 0.96% reported in 2010. Setting up a neonatal screening program and an awareness unit is necessary to assess the need for care services correctly.

Pairing parents and offspring's HemoTypeSC Test to validate results and confirm sickle cell pedigree: a case study in Kisangani, the Democratic Republic of the Congo

OBJECTIVES

HemoTypeSC^TM is one of the immunoassay methods currently used for the early diagnosis of Sickle Cell Disease (SCD) in newborns. Earlier diagnosis remains the key strategy for early preventive care needs and parents' education about the child's future well-being throughout his life. Before considering these children as sick and aligning them for regular medical monitoring, it may be valuable to confirm the HemoTypeSC result with a secondary laboratory testing method. In resource-limited settings, where confirmatory methods are not always available, we propose testing the parents to validate the HemoTypeSC result.

METHODS

This study explored this approach in the city of Kisangani. It was a prospective diagnostic accuracy study using genotype biological parents to evaluate HemoTypeSC's performance in the newborn.

RESULTS

Fifty-eight children born to 46 known mothers, and 37 known fathers, have been tested. The phenotyping showed that 41 (70.7%) children were SS, whose 37 were born to a couple AS/AS and 4 to a couple AS/xx. Of the 41 SS children, 8 (19.5%) were newborns and 33 (80.4%) were children; 12 (20.6%) children were AS, one of whom was born to a couple SS/AA and 11 to a couple AA/SS; 5 (8.6%) children were AA. In this population, the probability of offspring born to AS/AS parents being SS rather than AS is high (odds, 1.25). No statistical difference was observed between girls and boys. The pedigree of all 58 children has been confirmed.

CONCLUSION

We demonstrated that testing biological parents with HemoTypeSC is a reliable confirmatory method for newborn screening but it presents some limitations discussed in the present article.

Using dried blood spot on HemoTypeSC™, a new frontier for newborn screening for sickle cell disease in Nigeria

Background: HemoTypeSC is a rapid, point-of-care testing (POCT) device for sickle cell disease (SCD) that traditionally uses the capillary blood from heel stick collected at the point of testing, a procedure that makes mass screening cumbersome and less cost-effective. Using dried blood spots (DBS) on HemoTypeSC could mitigate this challenge. Therefore, this study aimed to determine the feasibility of eluting blood from DBS to read on HemoTypeSC.

Methods: DBS and fresh samples from heel sticks were collected from 511 newborns at the immunization clinics of six Primary Health Centers in Abuja, Nigeria. The two samples from each newborn were analyzed using HemoType SC and then compared with the result of the isoelectric focusing (IEF) test.

Results: Of the 511 newborns, 241 were males and 270 were females. Standard HemoTypeSC (using fresh samples collected from heel sticks) and HemoTypeSC using DBS identified 404 (79.0%) HbAA, 100 (19.6%) HbAS, 6 (1.2%) HbSS, and 1 (0.2%) HbAC phenotypes. The IEF tests identified 370 (72.4%) HbAA, 133 (26.0%) HbAS, 5 (1.0%) HbSS, and 3 (0.6%) HbAC phenotypes. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy of HemoTypeSC using DBS, compared to standard HemoTypeSC POCT was 100%. IEF method showed for AA, AS, AC phenotypes; sensitivity; 84.7%, 67%,100% respectively, specificity; 67.6%, 86%, 99% respectively, PPV; 91.2%, 53%, 50% respectively, NPV; 52.7%, 91%, 100% respectively. For SS phenotype, IEF showed 100% specificity, sensitivity, PPV and NPV.

Conclusion: HemoTypeSC test using dried blood spot is as accurate as the standard point-of-care HemoTypeSC test. The use of DBS on HemoTypeSC could ensure better efficiency and cost-effectiveness in mass newborn screening for SCD.

Potential of point of care tests for newborn screening for sickle cell disease: Evaluation of HemotypeSC™ and sickle SCAN® in Tanzania

BACKGROUND

Sickle cell disease (SCD) is an important cause of <5 mortality. In Tanzania, it is estimated up to 11 000 children are born with SCD annually, making this the fifth country with the highest SCD annual births worldwide. The biggest challenge of expanding the service of newborn screening for SCD as the national health intervention in Tanzania is due to the high cost of the currently used assays and lack of rapid screening methods. Therefore, in this study, we assessed the diagnostic accuracy of point-of-care tests for SCD diagnosis in newborns.

AIM

To evaluate the sensitivity and specificity of HemotypeSC™ and sickle SCAN® in diagnosing SCD in newborns.

METHODS

Diagnostic accuracy of HemotypeSC™ and sickle SCAN® were evaluated in comparison to isoelectric focusing as a confirmatory method.

RESULTS

A total of 706 newborns were enrolled in the study. The sensitivity and specificity of HemotypeSC in detecting Hb SS, Hb AS and Hb AA phonotypes was 100%. The sensitivity and specificity of sickle SCAN® in detecting Hb SS, Hb AS and Hb AA phenotypes were 100%, 97% and 100% respectively.

CONCLUSION

Both POC tests displayed high accuracy in detecting SCD, we believe the introduction of either of these tests in health facilities will help in the early detection and management of SCD. In addition, the margin of cost per test is relatively affordable (1.4$ per test for HemotypeSC™ and 4.75$ for sickle SCAN®).