Patient selection and index date assignment for Study 2. (A) Flow chart of selection of patients with type 2 diabetes who did not have affective disorder (AD) for assessment of AD incidence. Subjects aged 50 years or over with a diagnosis of type 2 diabetes recorded more than once within 1 year or who had used any oral anti-hyperglycemic agent (OAA) for at least 3 months during the period 1996 to 2007, regardless of insulin usage. (B) Patients with no OAA exposure were eligible to serve in the matching process for the various OAA groups. Subjects with diabetes on sulfonylureas (SU) and/or metformin (Met) and their matched non-OAA treated counterparts had the same treatment initiation dates (that is, index dates) for follow-up of AD.
Wahlqvist et al. BMC Medicine 2012 10:150 doi:10.1186/1741-7015-10-150