Interventional clinical trials registered per million population per country worldwide

TL;DR

This paper analyzes global clinical trial registration rates per million people, showing that smaller Western countries lead in trial registrations.

Contribution

The study provides a comprehensive analysis of interventional clinical trial registrations per million population across countries from 1999 to 2022.

Findings

Denmark, Estonia, and Belgium top clinical trial registrations per million population (2009–2022).

Global trial registration increased significantly after international registration requirements became more widespread.

Smaller Western countries lead in trial registration rates compared to larger nations.

Abstract

Sweden and Denmark are amongst the countries which led the world in clinical trial publications per million population. We need, however, to also assess clinical research activities through trial registration rather than publication alone. Enforceable policies for trial registration before launch facilitated global and national clinical research assessments. The World Health Organisation (WHO) hosts the International Clinical Trials Registry Platform (ICTRP) for interventional clinical trials, with data from the year 1999 and onwards.

To identify the number of interventional clinical trials registered per million population per country worldwide during the 2009- to 2022-year period, and to examine whether registration activity increased in those years when international registration requirements became more widely adopted as compared to the 1999- to 2022-year period.

We used the WHO ICTRP to extract the yearly numbers of registered interventional clinical trials. We entered the data in Microsoft Excel. We analysed the two periods of years: from 2009 to 2022 with more complete registration of trials and from the whole period 1999 to 2022 with a slow catch-up. To obtain the trial registration activity by country, we divided the total number of interventional clinical trials registered by the country’s population in millions. Information on population numbers originated from the World Bank, the Central Intelligence Agency World Factbook, and The National Institute of Statistics and Economic Studies (of France) as of 2022. We collected data as of 03-01-2024.

In February 2022, there were 943,113 interventional clinical trials registered by country on the ICTRP. After excluding 32,309 trials with unknown country of origin, we analysed 910,804 trials registered in 229 countries and territories. For countries or territories with populations over 1 million, the top five in interventional clinical trial registrations per million population during the 2009- to 2022-year period were Denmark, Estonia, Belgium, The Netherlands, and New Zealand. For the 1999- to 2022-year period, these were Denmark, Estonia, Belgium, The Netherlands, and Latvia. The top five countries or territories, irrespective of population, for both periods were Pitcairn, The Vatican, Tokelau, Niue, and Denmark.

Since 1999, there has been worldwide growth in interventional clinical trial registrations, especially amongst top-contributing countries. The global average stands at approximately 97 registered trials per million people from 2009 to 2022, highlighting the need for continued efforts to improve trial registration and production. Smaller Western countries lead in interventional clinical trials per million population.

The online version contains supplementary material available at 10.1186/s13063-025-09185-y.

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