The PHARMO Diabetes Cohort

In the Netherlands, the GP is the gatekeeper controlling access to specialized medical care. Mandatory health insurance ensures that every resident is registered with a GP, thus providing an excellent basis for research in an open population. Most residents are also registered with a pharmacy, allowing follow-up of patients stretching out to over 10 years.

The PHARMO Diabetes Cohort includes over 300.000 diabetes patients identified through ICPC coding, antihyperglycaemic drug prescriptions or diabetes integrated care program assessments in the GP Database, or through antihyperglycaemic drug dispensings in the Out-patient Pharmacy Database. In general, diabetes care can be divided into type 2 diabetes, for which the GP is primarily responsible, and type 1 and other rare types of diabetes (gestational diabetes, MODY, LADA), for which patients are primarily monitored by an internist or endocrinologist.

Since 2005, a type 2 diabetes integrated care program was set up involving multiple disciplines, such as GPs, dieticians, podologists and ophthalmologists into the monitoring and care for diabetes type 2 patients. During quarterly and yearly check-ups disease indicators such as HbA1c, hypoglycaemic events, renal function, diabetic foot and retinopathy, and cardiovascular risk factors such as blood pressure, weight, lipids, and smoking habits are monitored. Dieticians provide life style advice. Micro- and macrovascular complications are structurally assessed during check-ups, and all specialists update the GP on any findings regarding patients that are in their care. Health insurance companies use process and disease indicators to financially incentivise the GPs to actively follow-up on patients and accurately document the provided care, which has resulted in an increasingly complete registration of diabetes type 2 patients.

Linkage between the Out-patient Pharmacy Database and the Clinical Laboratory database, which contains blood and urine tests ordered by both GPs and specialists, allows glycaemic, lipid and renal assessment of all diabetes patients. Linkage to the Hospitalisation Database allows assessment of major cardiovascular events. Linkage to the National Cancer Registry on a study basis will allow assessment of cancer outcomes as well.

Overall, the PHARMO Diabetes cohort allows us to perform a variety of (pharmaco-)epidemiological studies regarding diabetes, such as patient-level antihyperglycaemic treatment patterns, evolution of HbA1c over time, cardiovascular complications associated with treatment, etcetera. Yearly updates of this cohort, with increasing quality and longer period of registration, ensure that we will continue to expand our possibilities to help answer your questions.