General descriptive information from the two samples of clinical trials registered in 2008/2009 and in 2012.

1 The number of registries that provide data to the ICTRP has increased from nine to fifteen in between 2008/2009 and 2012. Registry acronyms stand for: ClinicalTrials.gov (CT.gov), Japan Primary Registries Network (JPRN), Iranian Registry of Clinical Trials (IRCT), Australian New Zealand Clinical Trials Registry (ANZCTR), EU Clinical Trials Register (EU-CTR), International Standard Randomized Controlled Trial Number Register (ISRCTN), Chinese Clinical Trial Register (ChiCTR), Clinical Trials Registry - India (CTRI), German Clinical Trials Register (DRKS), The Netherlands National Trial Register (NTR), Clinical Research Information Service (CRiS) Republic of Korea, Pan African Clinical Trial Registry (PACTR), Cuban Public Registry of Clinical Trials (RPCEC), Sri Lanka Clinical Trials Registry (SLCTR) and Brazilian Clinical Trials Registry (ReBec).2 Other sponsors consisted of persons that were registered as primary sponsor, non-governmental organizations, collaborative research institutions and clinical research organizations.3 Overlap was possible, total in this category was greater than 731 in 2008/2009 and greater than 386 in 2012.4 Genetic interventions consisted of gene transfer therapy and somatic cell transplants.5 The presence of study phase in records was analysed separately for trials in drugs, biologicals or vaccines. 2008/2009: Of 439 trials researching these types of interventions, study phase was reported in 370 records (84.3%). 2012: Of 221 trials researching these types of interventions, study phase was reported in 172 records (77.8%).