Crohn's disease (CD) is a chronic gastrointestinal inflammatory disease characterized by relapse and progression. The incidence and prevalence of IBD are increasing in different regions around the world, indicating its emergence as a global disease. Though modern medical therapies including immunomodulators and biologic agents have revolutionized treatment of CD, the occurrence of steroids-dependence and resistance or intolerance to medical therapy is quite common. The limitation of present therapeutic management and the high expense of biologic agents leads to the treatment of CD become "refractoriness". The occurrence rate of steroids-dependence and resistance or intolerance to thiopurine therapy is quite high during the course of CD. Approximately 38% of cases required surgery within 10 years. Therefore, the management of such refractory CD remains a great therapeutic challenge for clinicians.

Thalidomide is an oral agent that has immunomodulatory, antiangiogenic and TNF(tumor necrosis factor)-a- suppressing effects. The potential role for thalidomide in the treatment of refractory paediatric and adult CD has been investigated in more and more small open-label studies and retrospective case series. Recently, a randomized controlled trial showed thalidomide improved clinical remission at 8 weeks of treatment and longer-term maintenance of remission in pediatric refractory CD. Gerich et al reported in a retrospective study that thalidomide improved long-term outcomes among 37 refractory CD adults followed up for a median of 58 months. However, the dose of thalidomide used in these studies ranged from 50mg/d to 150mg/d, and the occurrence rate of side effects reported variously but all quite high. The side effects related to the dose of thalidomide were the major concerns of using it in CD. Moreover, the effect of thalidomide on endoscopic response including mucosal healing which is a more objective and important outcome in CD was rarely reported. Therefore the aim of this study is to investigate the efficacy on clinical and endoscopic response and the adverse effects of using low-dose thalidomide in active adult CD patients.

Inclusion Criteria:

A CDAI score greater than 150 at baseline was required for inclusion .(1) steroid-dependent: unable to reduce steroids below the equivalent of prednisone 10 mg/day (or budesonide below 3 mg/day) within 3 months of starting steroids, or who have a relapse within 3 months of stopping steroids.(2) thiopurines-non-responsive: active disease or clinical relapse despite administration of azathioprine (1.5-2 mg per kg per day) or 6-mercaptopurine (0.75-1.5 mg per kg per day) for 4 months. (3) thiopurines- intolerant: intolerance to or adverse events of thiopurines.

The exclusion criteria were (1) isolated L4 CD; (2) disease including symptomatic stenosis of intestine or abdominal abscess requiring immediate surgery; (3) Current or past history of malignancy or organ transplantation; (4) Serious infections within 3 months; (5) Previous history of neuropathy or symptoms of neuropathy or abnormal electromyography prior to thalidomide; (6) infliximab treatment in the previous 8 weeks; (7) progressive or uncontrolled renal, hepatic, hematological, pulmonary and cardiac disease and（8）ongoing pregnancy.