Table 1:

Features of the databases included in the study

Database	Country	Type of database and setting	Study period	Diagnosis coding	Prescription coding	Source population
AARHUS	Denmark	NHS-linked regional database (northern and central regions); community, and in- and outpatient hospital settings	2000–2010	ICD-10	ATC	1 559 718
ERD	Italy	NHS-linked regional database (Emiglia-Romagna region); community setting	2005–2010	ICD-9-CM	ATC	6 079 798
HSD-CSD-LPD	Italy	Nationwide general practice database; community setting	2000–2010	ICD-9-CM and free text	ATC	1 240 561
GePaRD	Germany	Nationwide general practice database; community and hospital settings	2005–2009	ICD-10-GM	ATC	7 285 935
IPCI	Netherlands	Nationwide general practice database; community setting	1998–2010	ICPC and free text	ATC	1 016 632
PHARMO	Netherlands	Nationwide record linkage system; community setting	1999–2009	ICD-9-CM	ATC	4 625 868
THIN	United Kingdom	Nationwide general practice database; community setting	1997–2010	Read codes and free text	BNF/multilex	6 951 894

Note: AARHUS = Aarhus University Hospital Database; ATC = Anatomic Therapeutic Chemical drug classification; BNF = British National Formulary codes; ERD = Emilia-Romagna Database; GePaRD = German Pharmacoepidemiological Research Database; HSD-CSD-LPD = Health Search Database Cegedim Strategic Data Longitudinal Patient Database; ICD-9-CM = International Classification of Diseases, ninth edition, clinical modification; ICD-10 = International Classification of Diseases, 10th edition; ICD-10-GM = International Classification of Diseases, 10th edition, German modification; ICPC = International Classification of Primary Care; IPCI = Integrated Primary Care Information Database; NHS = National Health Service; THIN = The Health Improvement Network.