This study examined the diagnostic accuracy of nine indices to discriminate between patients with mild-to-moderate (haemoglobin 8.5 - 11 g/dI) or moderate-to-severe (haemoglobin < 8.5 g/dI) iron deficiency anaemia (IDA) from those with beta-thalassaemia (beta-TT) (n = 100 per group). Indices examined were red blood cell (RBC) count, RBC distribution width (RDW), Mentzer index (MI), Shine and Lal index (S&L), England and Fraser index (E&F), Srivastava index (S), Green and King index (G&K), RDW index (RDWI), and Ricerca index (R). Index sensitivity, specificity, and positive and negative prognostic values were examined. Youden's indices were calculated and showed: S&L > G&K > E&F > RBC = RDWI > MI > S > R > RDW to differentiate between P-TT and mild-to-moderate IDA; and S&L > G&K > E&F = RDWI > RBC > R > MI > S > RDW to differentiate between beta-TT or moderate-to-severe IDA. For both groups, S&L and G&K offered the best discrimination and RDW the worst. S&L showed the highest Youden index for beta-TT and IDA discrimination, but sensitivity and specificity were not 100%. In both mild and severe IDA, the S&L index may be used to differentiate cases of beta-TT from IDA cases, but large clinical trials are needed to explore this further.
