| Database | Source of Original Data | Search Terms in Web of Science | Years Searched | Filtering Method |
|---|---|---|---|---|
| CPRD | Web of Science | Clinical Practice Research Database, CPRD and GPRD | 1993–2013 | Posters and reports were excluded |
| QResearch | Web of Science | QResearch | 2004–2013 | Posters and reports were excluded |
| THIN | UCL | Publication authors and year used as search criteria to verify | 2004–2013 | Posters and reports were excluded |
| HES | Web of Science | HES Secondary Care Database | 1996–2014 | Posters and reports were excluded |