1. Systematic literature review and meta-analysis

Systematic literature reviews have been/will be conducted using the PUBMED, EMBASE and Cochrane Central Register of Controlled Trials databases. Meta-analyses have been/will be performed for data synthesis, heterogeneity assessment, sensitivity analysis and assessment of publication bias.  

2. Population-based electronic healthcare database studies

The population-based electronic healthcare database studies have been/will be conducted using a British and a Dutch data source. The first source is the UK Clinical Practice Research Datalink (CPRD), the world’s largest primary care database, which will be used to compare the outcomes resulting from the Dutch data with those from the British data, and increase the robustness of the studies. The CPRD contains data of over 11 million British patients between 1987 and 2013, representative of the UK population. The second source is the Utrecht Primary Care Research Network (UPCRN) database which presently contains data of approximately 2,400,000 patients from 140 general practitioners in the vicinity of Utrecht, the Netherlands.