Database: thrombosis_prediction
Question: How many patients with a normal Rhuematoid Factor has a positive measure of degree of coagulation?
SQL: SELECT COUNT(DISTINCT T1.ID) FROM Patient AS T1 INNER JOIN Laboratory AS T2 ON T1.ID = T2.ID INNER JOIN Examination AS T3 ON T3.ID = T2.ID WHERE (T2.RA = '-' OR T2.RA = '+-') AND T3.KCT = '+'