RESUMO
OBJECTIVE: To evaluate the efficacy of NESTROFT (Naked Eye Single Tube Red Cell Osmotic Fragility Test) as a screening tool for detection of beta thalassemia trait. DESIGN: Prospective study. SETTING: Field camps in various parts of Gujarat and Maharashtra States. METHODS: A total of 2525 subjects were screened. NESTROFT, complete hemogram including red cell indices and calculation of Mentzer's Fraction (MF) and discriminant functions (DF1-4) were done in all subjects. HbA2 was performed in 830 initial subjects to compute sensitivity, specificity and predictive values for various parameters. RESULTS: NESTROFT (sensitivity 94.4%), as a single screening parameter was superior to any of the other evaluated parameters individually, besides being cost effective. Mean corpuscular volume (MCV) < 80 fl followed NESTROFT closely (sensitivity 93.7; p > 0.05). MCV < 75 fl had a significantly (p < 0.001) lower sensitivity (87.3%) in comparison to both of these parameters. In contrast, MF, DF1, DF2, DF3 and DF4 did not meet the requirements of a good screening test with sensitivity values of 66.2%, 54.9%, 47.2%, 64.1% and 55.6%, respectively. NESTROFT in combination with MCV < 80 fl proved 100% sensitive. However, the combination was not cost effective. CONCLUSION: NESTROFT is a sensitive, cost effective, rapid and reliable screening test for detection of beta thalassemia trait in a population.