“…Registries, such as the ARAD and the BSRBR have taken steps to recruit control samples of patients whereas other registries have initiated data-linkage efforts with other existing sources, such as the Haemostasis Registry's link with ASCTS. Health insurance databases offer another useful resource for reliably capturing large numbers of patients, monitoring the course of disease, assessing drug utilization, and following patient groups over long time horizons [11]. Because of a lack of clinical detail in these databases, linkage to clinical registries is becoming increasingly useful, facilitating a linked-data source which minimizes selection bias, allows identification of a control group, and contains detailed clinical data for sufficient risk adjustment.…”