Graphical representation of the three different treatment stages: Users of GTZ drugs and other antidiabetic drugs classified according to first- or second-line mono- or combination therapy at the index date.

<p>For instance, to be a glitazone user in category (2), first-line non-GTZ treatment for diabetes was discontinued after 1999 when a GTZ was prescribed as second-line monotherapy. A patient could be matched to a GTZ user in category (2) if they had received an antidiabetic drug other than a GTZ (for example: Metformin) but stopped using their first-line antidiabetic treatment after 1999 and began taking another drug (for example: Sulfonylurea) as monotherapy after at least 12 months of registered follow-up.</p

Pictorial representation of the self-controlled case series design, showing the observation period for a single individual.

<p>Pictorial representation of the self-controlled case series design, showing the observation period for a single individual.</p

IRR of PD adjusted for potential confounders.

<p>* Main analysis: IRR for the association between GTZ use and incident PD using conditional Poisson regression to control for gender, age, practice, and treatment stage</p><p>IRR of PD adjusted for potential confounders.</p

IRR of PD: GTZ-exposed group versus the other antidiabetic drug-exposed group.

<p>* Adjusted for matched variables (age, gender, practice, and treatment stage) by conditional Poisson regression analysis.</p><p>** The rate of PD for current users of GTZ was originally divided into exposed <6 months, 6–12 months, and 1–2 years, but these cells were combined to avoid small cells that could compromise anonymity. The crude rates in these three periods were all similar at between 4.36 and 4.94, so there was no suggestion of important variation in that time period.</p><p>IRR of PD: GTZ-exposed group versus the other antidiabetic drug-exposed group.</p

Identification of study participants.

<p>CCW, Chronic Conditions Data Warehouse; TIA, transient ischemic attack.</p