title: Low-dose azathioprine is effective in maintaining remission in steroid-dependent ulcerative colitis: results from a territory-wide Chinese population-based IBD registry.
abstract: BACKGROUND
  Whether low-dose azathioprine (AZA) is effective in maintaining remission in patients with steroid-dependent ulcerative colitis (UC) remains unclear. We assessed the efficacy and safety of low-dose AZA in a Chinese population with UC.
  
  
  METHODS
  We identified steroid-dependent UC patients in clinical remission on AZA maintenance therapy from a territory-wide IBD Registry. Standard- and low-dose AZA were defined as at least 2 mg/kg/day and less than 2 mg/kg/day, respectively. Relapse rates were analyzed by Kaplan-Meier analysis and compared using log-rank test.
  
  
  RESULTS
  Among 1226 UC patients, 128 (53% male, median duration on AZA 44 months) were included. Median maintenance AZA dose was 1.3 mg/kg/day. 97.7% of the patients were on concomitant oral 5-aminosalicylic acid. Cumulative relapse-free rates in patients on standard-dose and low-dose AZA were 71.2%, 52.8% and 45.2%, and 71.8%, 55.3% and 46.2% at 12, 24 and 36 months, respectively (p = 0.871). Relapse rate within 12 months was higher in patients who withdrew compared with those who maintained on AZA (52.6% versus 29.4%; p = 0.045). Mean corpuscular volume increased after AZA therapy in both of the low-dose [median (interquartile range, IQR): 88.2 (81.4-92.2) versus 95.1 (90.1-100.9) fl, p < 0.001] and standard-dose subgroups [median (IQR) 86.8 (76.9-89.9) versus 94.7 (85.9-99.7) fl, p < 0.001]. Leukopenia occurred in 21.1% of the patients. Patients on standard dose had a higher risk for leukopenia than those on low-dose AZA [odds ratio (OR) 3.9, 95% CI 1.9-8.2, p < 0.001].
  
  
  CONCLUSIONS
  In the Chinese population, low-dose AZA is effective for maintaining remission in steroid-dependent UC patients. Standard-dose AZA was associated with more than threefold increased risk of leukopenia.
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China Department of Gastroenterology & Hepatology, Beijing Friendship Hospital, Capital Medical University, Beijing Digestive Disease Center, National Clinical Research Center for Digestive Diseases, China.
authors.forename: Hai Yun
authors.initials: HY
authors.lastname: Shi
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Francis K L
authors.initials: FK
authors.lastname: Chan
authors.affiliation: Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
authors.forename: Wai Keung
authors.initials: WK
authors.lastname: Leung
authors.affiliation: Department of Medicine and Geriatrics, Tuen Mun Hospital, Hong Kong, China.
authors.forename: Michael K K
authors.initials: MK
authors.lastname: Li
authors.affiliation: Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
authors.forename: Chi Man
authors.initials: CM
authors.lastname: Leung
authors.affiliation: Department of Medicine, Queen Elizabeth Hospital, Hong Kong, China.
authors.forename: Shun Fung
authors.initials: SF
authors.lastname: Sze
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Jessica Y L
authors.initials: JY
authors.lastname: Ching
authors.affiliation: Department of Medicine and Geriatrics, United Christian Hospital, Hong Kong, China.
authors.forename: Fu Hang
authors.initials: FH
authors.lastname: Lo
authors.affiliation: Department of Medicine, Tseung Kwan O Hospital, Hong Kong, China.
authors.forename: Steven W C
authors.initials: SW
authors.lastname: Tsang
authors.affiliation: Department of Medicine and Geriatrics, Caritas Medical Center, Hong Kong, China.
authors.forename: Edwin H S
authors.initials: EH
authors.lastname: Shan
authors.affiliation: Department of Medicine, North District Hospital, Hong Kong, China.
authors.forename: Lai Yee
authors.initials: LY
authors.lastname: Mak
authors.affiliation: Department of Medicine and Geriatrics, Kwong Wah Hospital, Hong Kong, China.
authors.forename: Belsy C Y
authors.initials: BC
authors.lastname: Lam
authors.affiliation: Department of Medicine, Alice Ho Miu Ling Nethersole Hospital, Hong Kong, China.
authors.forename: Aric J
authors.initials: AJ
authors.lastname: Hui
authors.affiliation: Department of Medicine, Yan Chai Hospital, Hong Kong, China.
authors.forename: Wai Hung
authors.initials: WH
authors.lastname: Chow
authors.affiliation: Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong, China.
authors.forename: Marc T L
authors.initials: MT
authors.lastname: Wong
authors.affiliation: Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong, China.
authors.forename: Ivan F N
authors.initials: IF
authors.lastname: Hung
authors.affiliation: Department of Medicine, Queen Elizabeth Hospital, Hong Kong, China.
authors.forename: Yee Tak
authors.initials: YT
authors.lastname: Hui
authors.affiliation: Department of Medicine and Geriatrics, Caritas Medical Center, Hong Kong, China.
authors.forename: Yiu Kay
authors.initials: YK
authors.lastname: Chan
authors.affiliation: Department of Medicine, North District Hospital, Hong Kong, China.
authors.forename: Kam Hon
authors.initials: KH
authors.lastname: Chan
authors.affiliation: Department of Medicine and Geriatrics, Kwong Wah Hospital, Hong Kong, China.
authors.forename: Ching Kong
authors.initials: CK
authors.lastname: Loo
authors.affiliation: Department of Medicine and Geriatrics, Princess Margaret Hospital, Hong Kong, China.
authors.forename: Carmen K M
authors.initials: CK
authors.lastname: Ng
authors.affiliation: Department of Medicine, Pamela Youde Nethersole Eastern Hospital, Hong Kong, China.
authors.forename: Wai Cheung
authors.initials: WC
authors.lastname: Lao
authors.affiliation: Department of Gastroenterology, Chelsea and Westminster Hospital, London, UK.
authors.forename: Marcus
authors.initials: M
authors.lastname: Harbord
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Justin C Y
authors.initials: JC
authors.lastname: Wu
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Joseph J Y
authors.initials: JJ
authors.lastname: Sung
authors.affiliation: Department of Medicine and Therapeutics, Institute of Digestive Disease, State Key Laboratory of Digestive Disease, LKS Institute of Health Science, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Siew C
authors.initials: SC
authors.lastname: Ng
keywords: azathioprine; low dose; steroid-dependent ulcerative colitis