GSTM1 and Hematemesis: As for each one of these clinical signs, the relatively high specificity was 97.9% for shock, 96.4% for red stool, 85.5% for red hematemesis, 76.7% for Hb ≤75 g/L, and the sensitivity was 50.8% for red hematemesis, 47.5% for Hb ≤75 g/L, 14.2% for red stool, and 10.9% for shock.