Trends in incidence of first diabetic foot ulcer and mortality in patients with T1 AND T2 DM

Date of ISAC Approval: 
Lay Summary: 
Diabetes Mellitus (DM) is a chronic disease, characterized by an impaired glucose metabolism and is often accompanied by severe complications. These complications can lead to peripheral neuropathy, which alongside peripheral arterial disease can lead to diabetic foot ulcers. Such ulcers often precede amputations and are associated with high morbidity and even mortality. Much is already known about the risk factors for developing diabetic foot ulcers, but even in high-risk populations, the overall prevalence and incidence is reported to be quite limited. In this study, we want to investigate the trend in development of diabetic foot ulcers over time. Furthermore, we will describe these trends for several subgroups including people with type I and type II diabetes.
Technical Summary: 
In CPRD, all patients with a diagnosis of diabetes will be included in the initial study cohort. Our primary outcome will be trends in incidence of first Diabetic Foot Ulcer (DFU). Patients will be followed from the index date up to the date of death, end of data collection, end of study period, or the date of a DFU, whichever comes first. DFUs will be identified by use of read codes. The incidence rates in each calendar year will be calculated as the sum of the DFUs in that year divided by the total time at risk in that given calendar year. This will be expressed as the number of events per 1000 person-years. We will break down these rates by gender, age categories, and type of diabetes (T1DM or T2DM). Furthermore, the following patient characteristics at the time of the first DFU will be determined, age, time since index date as a proxy for diabetes duration and history of Charcot Neuroarthropathy (CN). For patients with a diagnosis of a DFU we will also calculate the 1- and 5-year mortality rates. All analyses will be stratified by sex, age categories and type of diabetes (T1DM and T2DM).
Health Outcomes to be Measured: 
1) Trends in incidence of first DFU and hospitalization for first DFU 2) The following patient characteristics for all patients with a first DFU: age, duration of diabetes, history of CN at the date of the first DFU 3) 1- and 5-year mortality rates in patients with a first DFU.

Frank de Vries - Chief Investigator - Utrecht University
Frank de Vries - Corresponding Applicant - Utrecht University
Johan Roikjer - Collaborator - Aalborg University Hospital
Johanna Annemariek Driessen - Collaborator - Utrecht University
Joop van den Bergh - Collaborator - Maastricht University
Dr Morten Jensen - Collaborator - Aalborg University Hospital
Nicolaas Schaper - Collaborator - Maastricht University
Professor Niels Ejskjaer - Collaborator - Aalborg University Hospital
Dr Olaf Klungel - Collaborator - Utrecht University
Peter Vestergaard - Collaborator - Aalborg University Hospital