PTGS2 and rheumatoid arthritis: In fact, in a network meta-analysis that examined the cardiovascular and gastrointestinal safety of various NSAIDs, including COX-2 inhibitors, in patients with OA or rheumatoid arthritis, found that COX-2 inhibitors were associated with an increased risk of gastrointestinal adverse events compared to placebo or non-selective NSAIDs.