More patients receiving either dose of tofacitinib had an improvement in the activity of their RA than those receiving placebo. Abnormalities in certain blood tests were seen in some patients who received tofacitinib, including certain blood counts, cholesterol level, and kidney function. These usually did not cause a known problem during the study, although some patients did need to stop the drug. Among patients taking tofacitinib, 4 developed opportunistic infections (such as tuberculosis), 4 experienced heart problems, and some developed serious infections. One patient's death was thought to be related to tofacitinib. Such problems have been seen in other studies of tofacitinib, and no new problems were identified in this study.