We also investigated the association between noncontinuous use and relapse or recurrence within 1 year of starting treatment and the factors associated with noncontinuous antidepressant use. Material and Methods Study design, source of data, and patient population This retrospective cohort study was conducted in the Prince of Wales Hospital (PWH) in Shatin, Hong Kong. The study was approved by the Joint Chinese University

of Hong Kong and New Territories East Cluster Inhibitors,research,lifescience,medical (CUHK-NTEC) Clinical Research Ethics Committee (CREC) in July 2008. Eligible patients were identified through data retrieval using the Clinical Data Analysis and Reporting System (CDARS). This centralized-computerized database stores longitudinal clinical information including patient demographics, prescription, and dispensing records, and diagnosis patients

received from all public hospitals in Hong Kong. Patients were included if Inhibitors,research,lifescience,medical (1) he or she was aged >18 years, (2) was attending Psychiatric Specialist Outpatient Clinic (SOPD) of PWH during the period between 1st January 2006 to 31st December 2007, (3) had an antidepressant dispensed during the study period, and Inhibitors,research,lifescience,medical (4) were diagnosed with major depressive disorders according to the International Classification of Disease-10 classification of mental and behavioral disorders. Subjects were excluded if they had (1) concurrent diagnosis Inhibitors,research,lifescience,medical of bipolar disorder, obsessive-compulsive disorder, psychosis, schizophrenia, substance abuse, post-traumatic stress disorder, acute stress disorder, and panic

disorders, or (2) a diagnosis of dementia or mental retardation, or (3) a prescription of antidepressants 6 months prior to the study period, or (4) documented concurrent psychiatric-related follow-ups in other health care settings (where they may also had been prescribed antidepressants), or 5) history of drug overdose or suicide. If there were more than one period of antidepressant use during the study period, Inhibitors,research,lifescience,medical only the first episode was counted. Electronic patient records were then reviewed to confirm the eligibility. Further information regarding the antidepressant use and relapse and recurrence after treatment initiation was supplemented by reviewing the written medical records. Data collection A standard form was designed for collecting ADAMTS5 patient-, illness- and treatment-related parameters. These included demographics such as age, gender, type of accommodation (as an indirect indictor for socioeconomic status) and marital status. Details of treatment regimen including drug name, dosage, frequency, duration, and prescription refill pattern were documented. Other treatment-related factors such as the frequency of follow-up were also recorded.