Number of clinical trials by year, country, WHO region and income group (1999-2017)

Published: January 2018

The number of trials listed in the WHO International Clinical Trials Registry Platform (ICTRP) is reported by year, country, WHO region and income group for the period 1999–2017. Note that the ICTRP comprises both interventional and observational trials. See more on scope of ICTRP below.

See also:
Number of clinical trial registrations by year, location, disease and phase of development
Percent of clinical trials with enrollment year preceding registration year

What you see | Scope and limitations |  Data sources |  Current version

 

What you see

The data visualization above shows the trend in the registration of trials on ICTRP from 1999 to 2017, grouped by WHO region (top chart), and income group (middle chart). The year corresponds to the date of enrollment of the first trial participant. (Multicountry trials conducted in the same region or income group are counted as one trial in the top and middle charts.)

The bottom chart shows the number of recruiting trials by country, colour coded by WHO region. (Here, a multicountry trial is counted once in each participating country.)

Points to note:
  • Over the analysis period there was a steady rise in the number of newly recruiting trials registered on ICTRP for most WHO regions. However, the number of such trials registered in WHO’s Europe, Americas and Western Pacific regions has increased at a much higher rate than in other regions. For example, in 2017 the number of trials registered in Western Pacific (11,644) was more than 22 times higher than that in Africa (513).
  • In the Western Pacific region, the increase comes primarily from increases in trial registration in Japan and China (which rank as first and second in the Western Pacific region for trial registries respectively). This may be explained by the following facts:
    -- In 2009, trial registration was added as a requirement of ethical guidelines for medical research in Japan.
    -- In China, an increasing number of Chinese journals, government funding agencies, universities, and hospitals require trials to be registered.
  • Exploring the trends by income group (middle chart), show that the rise in the number of newly recruiting trials registered on ICTRP was much higher in high income group countries than in other income groups. For example, in 2017 the number of trials registered in high income countries (23,500) was more than 98 times higher than low income countries (239).

To explore the data further:

  • Hover the cursor on a data element of interest (for example a point on the trend line or bar beside each country) to see more information in a popup window.
  • To filter results for a different range of years use the year slider (top left). To select a single year, move both sliders together to the desired year.
  • To filter results by region or income group, click a region (top chart) or income group (middle chart) from the key. The bottom chart will update the list of countries with the selected option.
  • To explore results for a specific country, select the bar beside the desired country name in the bottom chart. The top charts will display the trial registration trends for that country, colour coded by the corresponding region (top) or income group (middle).
  • Note that the number of trials in the bottom chart may be higher than the trials in the top or middle charts as one trial per region is counted once in the top and middle charts, and for every country participating in that trial in the bottom chart.
  • Hold the ctrl key to select more than one option, for example two regions or countries.
  • Undo a selection by clicking ‘undo’ or ‘reset’ near the bottom of the page or by clicking the same element again.

Limitations of the data and analysis

  • There are several gaps in the ICTRP data source which required data cleaning to uniformly classify data elements when possible. In some cases no information was available, e.g. on the country where the trial is conducted (0.1%).
  • The data presented in this visualization utilizes classifications that are not mutually exclusive. For example, a registered trial can recruit participants from multiple countries and regions. In this case, the trial will be counted once per region in the top chart but once per country in the bottom chart. The total number of trials across the two top charts and the bottom chart is therefore not equivalent.
  • The analysis will be updated at regular time points but time lags with the scheduled updates by the data sources are inevitable. Accuracy and completeness of the information is the responsibility of the data source, see  terms and conditions of use.