PTGS2 and ulcer disease: In a post hoc subgroup analysis of selective COX-2 inhibitor users, there were no significant differences in concomitant use of low-dose aspirin (8 cases (47%); 19 controls (38%); p = 0.51), non-selective NSAIDs (3 cases (18%); 10 controls (20%); p = 0.83) or PPIs (3 cases (18%); 17 controls (34%); p = 0.20); neither were there significant differences in concomitant use of coumarin, heparin, steroids or high-dose H2RAs or in ulcer history.