Prediction and diagnosis of sickling disorders in neonates

Neonatal screening of sickle cell anemia: a preliminary report

OBJECTIVE

To evaluate feasibility of systematic neonatal screening for sickle cell disease in Chhattisgarh.

METHODS

A pilot study was done from February 2008 through January 2009 in Department of Pediatrics & Neonatology, Pt. J.N.M. Medical College & Dr.B.R.A.M. Hospital, Raipur (Chhattisgarh) on a total of 1,158 neonates. Blood samples from the neonates were taken after 48 h of birth on filter paper for detection of sickle cell anemia using Biorad hemoglobin variant Neonatal sickle cell short programme by high performance liquid chromatography (HPLC). On follow up, cases were analyzed by HPLC using Beta thalassemia short program to rule out false negative case and other hemoglobin variants.

RESULTS

Of the 1,158 neonates screened, 628 were boys (54.2%) and 530 were girls (45.8%). Sickle cell disease was found in 3 cases (0.2%) (95%C.I 0.12-0.28), sickle cell trait was found in 68 cases (5.8%) (95%C.I 4.5-7.5). After 6-9 mo of age three cases of sickle cell diseases were reinvestigated, out of which one case turned out to be double heterozygous for sickle cell and beta thalassemia trait. Fourteen preterm neonates reported as normal in initial screening were called for follow up after 6 mo of age, 10 infants reported in OPD and 4 lost in follow up. These 10 infants were reinvestigated; 2 had sickle cell disease, 1 had sickle cell trait and 7 infants were normal. Sixty eight cases of sickle cell trait found with initial screening were also called for follow up after 6 mo of age; 61 cases reported in OPD between 6 mo to 1 y of age and 7 cases lost in follow up. Sixty one infants were reinvestigated; 60 had sickle cell trait and 1 had sickle cell disease which was reported earlier as Sickle cell trait (FAS). Thus on total follow up of cases, there were 5(0.4%) sickle cell disease, 61(5.26%) sickle cell trait, 1(0.08%) double heterozygous for sickle cell and beta thalassemia trait which needs mutation studies for thalassemia characterization (s/β(0) or s/β(+)).

CONCLUSIONS

Early detection of sickle cell disease (SS) done by neonatal screening will help in early prevention and management of complications in postnatal period.

The feasibility of using ethnicity as a primary tool for antenatal selective screening for sickle cell disorders: pointers from the research evidence

The Department of Health has announced a linked antenatal and neonatal screening programme for haemoglobinopathies by 2004 in a comprehensive national plan for the National Health Service in Britain. In response the National Screening Committee has commenced development work on how such a programme can best be implemented, including investigation of the effectiveness of a question about ethnic origin as a basis for selection. In addition, two recent health technology assessment reports have assessed alternative options for antenatal and neonatal haemoglobinopathy screening programmes in the United Kingdom. Both reports and commentators have emphasised the importance of developing a standardised instrument for collecting ethnicity data and recommended early development of such work. An examination of the evidence base on the use of ethnicity as a primary screening tool reveals substantial variability in practice and in the quality of data collected, with risk group misclassification as high as 20% against a recommended target of under 5.5%. The literature on the conceptual basis and structure of ethnicity questions, method of assignment in data collection, and level of resolution on categorisation is reviewed to identify the most appropriate content and format of a screening question for the haemoglobinopathies. Question options are evaluated, including the use of an extended 2001 Census classification and a 'non-North European' identifier and a candidate question based on 'family origins' is offered for debate. Finally, issues relating to the testing of the efficiency of an ethnicity question and the operationalising of its use for antenatal sickle cell screening are discussed.

Mapping the prevalence of sickle cell and beta thalassaemia in England: estimating and validating ethnic-specific rates

A range of estimates for sickle cell and beta thalassaemia have been derived for the different ethnic groups living in the U.K., reflecting uncertainty over the true population value in certain countries and the heterogeneity within and between countries of origin comprising the same ethnic group. These were validated against six community screening programmes, with the estimated range correctly predicting the number of affected births observed by the programmes. In England approximately 3000 affected babies (0.47%) carry sickle cell trait and 2800 (0.44%) carry beta thalassaemia trait annually: with approximately 178 (0.28 per 1000 conceptions) affected by sickle cell disease (SCD) and 43 (0.07 per 1000) by beta thalassaemia major/intermedia. Allowing for termination, about 140-175 (0.22-0.28 per 1000) affected infants are born annually with SCD and from 10 to 25 (0.02-0.04 per 1000) with beta thalassaemia major/intermedia. These are the first evidence-based rates for sickle cell and beta thalassaemia for use in the U.K., and should underpin the future planning of services. The long-term solution to monitoring changes in the rates of trait and disease in the population is to introduce a standardized instrument for collecting ethnicity for all community screening programmes.

Costing model for neonatal screening and diagnosis of haemoglobinopathies

AIM

To compare the costs and cost effectiveness of universal and targeted screening for the haemoglobinopathies; to compare the cost of two laboratory methods; and to estimate the cost effectiveness of programmes at different levels of prevalence and mix of haemoglobinopathy traits.

METHODS

A retrospective review of laboratory and follow up records to establish workload and costs, and estimation of costs in a range of circumstances was made in a haematology department and sickle cell and thalassaemia centre, providing antenatal and neonatal screening programmes in Inner London. The costs for 47,948 babies, screened during 1994, of whom 25 had clinically significant haemoglobinopathies and 704 had haemoglobinopathy traits, were retrospectively assessed.

RESULTS

The average cost per baby tested (isoelectric focusing and high power liquid chromatography) was 3.51 Pounds /3.83 Pounds respectively; the cost per case of sickle cell disease identified (IEF/HPLC) was 6738 Pounds /7355 Pounds; the cost per trait identified (IEF/HPLC) was 234 Pounds /255 Pounds; the cost per extra case of SCD and trait identified by universal programme varied.

CONCLUSIONS

IEF and HPLC are very similar in terms of average cost per test. At 16 traits/1000 and 0.5 SCD/1000 there was no significant identification cost difference between universal and targeted programmes. Below this prevalence, a targeted programme is cheaper but likely to miss cases of SCD. If targeted programmes were 90-99% effective, universal programmes would cease to be good value except at very high prevalence. Greater use of prenatal diagnosis, resulting in termination, and therefore fewer affected births, reduces the cost effectiveness of universal screening. Screening services should aim to cover a screened population which will generate a workload over 25,000 births a year, and preferably over 40,000.

[Neonatal detection of sickle cell disease in metropolitan France. Association française pour le dépistage et la prévention des handicaps de l'enfant (AFDPHE)]

Following the experimental program initiated in Martinique and Guadeloupe since 1983, a neonatal screening for sickle cell disease was extended to metropolitan France in 1990. It is presently applied to at risk newborns based on the parents ethnic origin, and associated with the screening for phenylketonuria, hypothyroidism and congenital adrenal hyperplaxia, in three regions. The laboratory method is reliable with a very limited number of false positive or false negative results. The cost effectiveness ratio appears very reasonable. All the children detected so far are correctly managed and have a normal development. This screening should be extended to the rest of France in the coming years.

Neonatal screening for sickle cell disorders: what about the carrier infants?

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Prenatal genetic counseling for hemoglobinopathy carriers: a comparison of primary providers of prenatal care and professional genetic counselors

Health personnel trained in medical genetics are insufficient to meet the demand for genetic services. Methods must be found to enable primary care providers to offer commonly needed genetic services themselves. In our recently reported community-wide prenatal screening program for hemoglobinopathies, 36% of women detected to have a hemoglobinopathy did not come to a tertiary center for counseling and thus may have not benefited from testing. To determine whether the efficiency of the program could be increased if counseling were provided by the prenatal care provider (obstetrician or family practitioner), we developed a pilot training program on the basis of our experience in offering such services and enlisted 68% of regional prenatal care providers to participate. The proportion of patients detected to have a hemoglobinopathy who received counseling was similar in the primary and tertiary provider groups: 59% versus 50%, respectively, for sickle trait, and 69% versus 66%, respectively, for beta-thalassemia trait. Knowledge after counseling was also similar for the primary and tertiary provider groups: 64% versus 66% (mean % correct), respectively, for sickle trait, and 79% versus 78%, respectively, for beta-thalassemia trait. However, the two provider groups significantly differed with regard to whether or not the patient had her partner tested. For sickle trait, it was 25% for the primary providers but 49% for the tertiary providers (P < .001). For beta-thalassemia trait, it was 47% for the primary providers but 78% for the tertiary providers (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal screening for hemoglobinopathies. III. Applicability of the health belief model

A comprehensive prenatal hemoglobinopathy screening program in Rochester, NY, has been described in a preceding paper in this issue of the Journal. A woman identified as a carrier may face three decisions. The first is whether to accept the offer of counseling. The second is whether to have her partner tested. If her partner also tests positive, then the third decision is whether to accept the offer of prenatal diagnosis. This report analyzes factors affecting her decision, with special attention being given to factors invoked by the Health Belief Model. Factors predicting that a patient who we identified as a carrier would come for counseling included the following: patient had no prior knowledge that she is a carrier (P less than .001), a gestational age less than 18 wk (P less than .01), and Caucasian race (P less than .05). For sickle cell trait counselees and beta-thalassamia trait counselees, factors found to predict patient's intent to have partner tested were the following: a greater postcounseling knowledge of the disease (P less than .009), a lesser perceived burden of intervention (P less than .011), and belief that the partner is also a carrier (P less than .008). Also for sickle cell trait counselees and beta-thalassemia trait counselees, factors predicting that the partner actually will be tested were the following: living with the partner (P less than .001), gestational age at identification less than or equal to 18 wk (P less than .001), a lesser perceived burden of intervention (P less than .002), and a greater perceived seriousness of the disease (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)