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Background: Thalassaemia is highly prevalent in Sri Lanka. The highest number of patients are seen in the North Western province, especially in the Kurunegala district. Screening of children and adults to detect beta thalassaemia carriers/trait using automated full blood counts and high performance liquid chromatography (HPLC) are only limited to few centers in Sri Lanka. In this context, the value of one tube osmotic fragility test (OFT) as a screening test is immense. Our study tried to determine the sensitivity and specificity of OFT in beta thalassaemia trait (BTT) in Sri Lanka.
Materials and Methods: This was a cross sectional study on randomly selected 700 subjects, carried out at National Thalassaemia Center (NTC), Kurunegala. Participants were categorized into four groups based on red cell indices, HPLC and serum ferritin assay as normal group, BTT group, iron deficiency anaemia (IDA) group and other haemoglobinopathies. OFT was performed on all cases.
Results: Out of 700 subjects 396 subjects (56.6%) were females and 304(43.4%) were males.
OFT gave definitely positive or equivocal results in 194 of 201 patients with BTT and 96.52% of sensitivity was observed. The test was false positive in 2 out of 268 (0.75%) normal subjects and 99.25% of specificity was observed. There were 3.48% (7/201) false negative results with a negative predictive value (NPV) of 97.44% and the positive predictive value (PPV) of the test was 98.97%.
Conclusion: One tube osmotic fragility test is a sensitive, cost effective, rapid and reliable primary screening test for detection of BTT in a population with financial restrictions.
El-Beshlawy A, Kaddah N, Moustafa A, Mouktar G, Youssry I. Screening for beta-thalassaemia carriers in egypt: Significance of the osmotic fragility test. Eastern Mediterranean health journal = La revue de sante de la Mediterranee orientale = al-Majallah al-sihhiyah li-sharq al-mutawassit. 2007;13(4):780-6.
Perera DM, Gunasekara D, Wijekoon A, Petrou M. Thalassaemia control in developing countries-the Sri Lankan perspective. The Ceylon Medical Journal. 2000;45(1):12-6.
Leung TN, Lau TK, Chung T. Thalassaemia screening in pregnancy. Current opinion in obstetrics & gynecology. 2005;17(2):129-34.
Menon SR, Khatkhatay MI, Dandekar SP, Patel ZM. Development and validation of an ELISA for hemoglobin‐A2: A novel method for β‐thalassemia screening in developing countries. Journal of Immunoassay and Immunochemistry. 2004;25(2):135-46.
Sanchaisuriya K, Fucharoen S, Fucharoen G, Ratanasiri T, Sanchaisuriya P, Changtrakul Y, et al. A reliable screening protocol for thalassemia and hemoglobinopathies in pregnancy an alternative approach to electronic blood cell counting. American journal of clinical pathology. 2005;123(1):113-8.
Fucharoen G, Sanchaisuriya K, Sae-ung N, Dangwibul S, Fucharoen S. A simplified screening strategy for thalassaemia and haemoglobin E in rural communities in south-east Asia. Bulletin of the World Health Organization. 2004;82(5):364-72.
Kattamis C, Efremov G, Pootrakul S. Effectiveness of one tube osmotic fragility screening in detecting beta-thalassaemia trait. Journal of Medical Genetics. 1981;18(4):266-70.
Cao A, Galanello R, Furbetta M, et al. Thalassaemia types and their incidence in Sardinia. J Med Genet. 1978;15:443–447.
Thool AA, Walde MS, Shrikhande AV, Talib VH. A simple screening test for the detection of beta thalassemia. Indian J Pathol Microbiol. 1998;41:423–426.
Panyasai S, SringamP, Fucharoen G, SanchaisuriyaK, Fucharoen S. A simplified screening test for a-thalassemia 1 (SEA type) using a combination of a modified osmotic fragility test and a direct PCR on whole blood cell lysates. Acta Haematol. 2002;108:74–78.
Raghavan K, Lokeshwar MR, Birewar N, Nigm V, Manglani MV, Raju NB. Evaluation of naked eye single tube osmotic fragility test in detecting beta-thalassemia trait. Indian Pediatr 1991;28:469–472.
National thalassaemia center, Kurunagela. Thalassaemia patients in Sri Lanka; 2008/2009. Available:http://thalassemia-srilanka.blogspot.com
Parikh U, Goswami H, Mehta R, Patel P, Gonsai R. Incidence of hemoglobinopathies in women attending antenatal clinics in their first trimester. NHL Journal of Medical Sciences. 2014;3(1).
Chow J, Phelan L, Bain BJ. Evaluation of single-tube osmotic fragility as a screening test for thalassemia. American journal of hematology. 2005;79(3):198-201.
Wild B, Bain BJ. Chapter 12 - Investigation of abnormal haemoglobins and thalassaemia. In: Bates SMLJB, editor. Dacie and Lewis practical haematology (tenth edition). Philadelphia: Churchill Livingstone. 2006;271-310.
Sarda H, Niveditha SR, Shivalingaiah N. Screening of β thalassemia trait among pregnant women with NESTROFT. Thalassemia Reports. 2015;5(1).
Singh S, Gupta S. Effectiveness of red cell osmotic fragility test with varying degrees of saline concentration in detecting beta-thalassaemia trait. Singapore medical journal. 2008;49(10):823-6.
Rakholia R, Chaturvedi P. Evaluation of nestroft as a screening test for beta thalassemia trait. JARBS. 2013;5(2):127-30.
Thomas S, Srivastava A, Jeyaseelan L, Dennison D, Chandy M. NESTROFT as a screening test for the detection of thalassaemia and common haemoglobinopathies—an evaluation against a high performance liquid chromato-graphic method. The Indian Journal of Medical Research. 1996;104:194-7.
Chakrabarti I, Kumar Sinha S, Ghosh N, Krishna Goswami B. Beta-Thalassemia Carrier Detection by NESTROFT: An answer in rural scenario? Iranian Journal of Pathology. 2012;7(1):19-26.
Sumera A, Ahmed S, Ali SA, Khanani R. Evaluation of Nestroft as a marker of differentiation between β-thalassemia trait and iron deficiency anemia. International Journal of Collaborative Research on Internal Medicine and Public Health. 2012;4:1560-6.
Manglani M, Lokeshwar MR, Vani VG, Bhatia N, Mhaskar V. 'NESTROFT'-an effective screening test for beta thalassemia trait. Indian pediatrics. 1997;34(8):702-7.
Himaxi R, Nanditha M, Priyanka G. Nestroft as a screening test for beta thalassemia. Journalijar. 2014;8:151-155.