[Sensitivity, specificity, and predictive values of the level of hemoglobin, hematocrit and platelet count as an activity index in ulcerative colitis].

INTRODUCTION: Ulcerative colitis (UC) is a disease characterized by relapsing and remitting non-infectious inflammation of the colorectal mucosa. Its heterogeneity makes assessment of the disease's activity a prerequisite for a rational choice of therapy. We aimed to determine sensitivity, specificity, positive and negative predictive values of hemoglobin, hematocrit, and platelets to develop a simplified activity index of UC. MATERIAL AND METHODS: Sixty patients with UC were included and submitted to measurements of hemoglobin, hematocrit, and platelets, as well as sigmoidoscopy and biopsy. Sensitivity and specificity, positive and negative predictive values were correlated with the reported degree of activity in the biopsy. Kruskal-Wallis test was used to determine differences between groups, and Pearson and Spearman rank tests were used to correlate each parameter with the degree of activity. A p value < 0.05 was considered statistically significant. RESULTS: The patients had moderate (n = 15), severe (n = 15), and normal histology as a control group (n = 15). Thirty-four (57%) were female and 26 (43%) were male. Average age was 26 +/- 12.8 years. Sensitivity and specificity for hemoglobin level was 51% and 100% for hematocrit, respectively, 51% and 100% for hematocrit, and 84% and 100% for platelet counts. Spearman's correlation for hemoglobin was r = -0.866 (p < 0.001), for hematocrit r = -0.864 (p < 0.001) and for platelets r = 0.928 (p < 0.001). CONCLUSIONS: Hemoglobin and hematocrit are useful to catalog the degree of activity of UC when it is severe. Platelet count may be a marker of severity at any time, due to its high sensitivity and specificity as a diagnostic test.