Patients were randomized in a 1:1:1 ratio to placebo, apremilast 20 mg BID and apremilast 30 mg BID. The duration of the study was approximately 5 years. The double blind period (when patients nor the physician knew whether placebo or apremilast was taken) was 24 weeks. At Week 16, participants who did not have either a ≥ 20% improvement or a ≥ 1 unit improvement from baseline in at least two of the four SpondyloArthritis international Society (ASAS) domains were entered in "early escape" from their current treatment in a double-blinded manner. However, such participants were permitted to continue in the study. At Week 24, participants may have entered a long-term extension phase for up to an additional 4.5 years (236 weeks). At "second escape" (at Week 24), apremilast 20 mg BID treated participants transitioned to receive double-blinded apremilast 30 mg BID and remained on double-blinded apremilast 30 mg BID because they continued to improve with a longer duration of treatment. After Week 24 and during the early portion of the long-term extension through Week 52, all participants continued on either double-blinded apremilast 20 mg BID or 30 mg BID treatment. After all participants had completed Week 52 or had terminated early from the study and the 52-week data base was locked, apremilast 20 mg BID or 30 mg BID treatment was provided.
