Usefulness of thyrogastric immune features as predictors of pernicious anaemia that lacks intrinsic factor antibody.

The study aims to evaluate the diagnostic utility of thyrogastric immune features in the identification of intrinsic factor antibody negative (IFA -ve) pernicious anaemia (PA) patients. Clinico-pathological features of 'intrinsic factor antibody positive (IFA +ve) PA' and 'IFA -ve presumed PA' Chinese patients in a single hospital (2001-2009) were studied. Coefficients of independent variables identified were used as weighted scores. The result was validated by patients (1994-2000) with Schilling test done. Comparison of 127 'IFA +ve PA' and 130 'IFA -ve presumed PA' patients showed four independent variables, namely (+) gastric parietal cell (GPC) antibody (OR, 2.907, 95%; CI, 2.346-3.468; P < 0.001), (+) antithyroid antibodies (OR, 3.098, 95%; CI, 2.496-3.70; P < 0.001), (+) gastric atrophy (OR, 3.827, 95%; CI, 3.041-4.64; P = 0.001), and (-) Helicobacter pylori (HP) organisms (OR, 0.134, 95%; CI, -1.60-1.869; P = 0.023). The respective scores were 1.067, 1.131, 1.342 and -2.012. Total scores for each patient ranged from 3.54 to -2.012. When the cut-off score 1.528 was applied to the validation sample (n = 75), the specificity of identifying IFA -ve PA was 100%, sensitivity 53%, positive predictive value 100%, and negative predictive value 36%. Patients with two out of three features, GPC, antithyroid antibodies, gastric atrophy, but without HP organisms; or three features with HP organisms, can be predicted to have PA.