3 May 2023

The DISTAL study performed by the DKF research groups of Marios Psychogios  and Urs Fischer shows how database-supported monitoring can be used in practice.


New methods of quality control in clinical trials can help to work more efficiently, reduce costs and improve data quality.

The DISTAL study offers a suitable setting

DISTAL is an international multicenter study with more than 500 planned patients recruited and treated at more than 40 international study sites. Enrollment of participants takes place in an emergency setting, as the study is investigating the treatment of stroke by endovascular therapy compared to drug therapy alone. At five defined time points, study-specific data points are collected for each patient and administered in a central database managed at DKF.

Centralised Data Monitoring (CDM)

using the DISTAL study as an example

What it covers
- completeness and plausibility of data
- timing of data entry
- protocol violations

- timeliness of data entry
- passing on corrections
- conducting visits
- follow-ups for SAEs

- data completeness
- site performance

Central point of contact for sponsor, study center, data management and monitoring teams

Number of initiated study sites
42 (Switzerland, Germany, Spain, Belgium, Finland, Portugal, Israel), thereof actively recruiting 30; further study sites planned in Italy and UK

Number of participants
planned 526, currently enclosed 171

Time for data review
planned 30 minutes per patient

Data reviews
Number of data entries: 298
Number of findings: 445

DISTAL study
More information

Data verification is managed timely and centrally

This central database offers the possibility to check the collected data continuously and in a timely manner. This method is called Centralised Data Monitoring (CDM). Which data points are reviewed using CDM, when, and how frequently is determined by the sponsor prior to the start of the study. CDM is a risk-adapted version of monitoring. Thus, not all aspects of a clinical trial are checked. This approach assumes that the sponsor has basic trust in the participating study sites regarding their practices of conduct.

The focus of the data reviewed via CDM is primarily on those that are critical to patient safety and overall data quality. For example, in the DISTAL study, checks are made to ensure that safety reports are recorded and forwarded correctly, or that parameters defined as study endpoints are collected correctly and that all visits take place at the specified times. In addition to CDM, source documents in remote monitoring visits and documents verifying the existence of study participants, i.e., consent forms and identification logs, will continue to be verified on-site as needed. Although monitoring visits still take place, their number and extent is greatly reduced with CDM.

A. Brehm und L. Balmer



"With Centralised Data Monitoring we have an additional contact point for our study sites, which is mostly perceived as supportive and not so much as a control body. The regular exchange ensures good data quality and consistent protocol compliance."

Luzia Balmer, Project Manager DISTAL study

Positive feedback from all parties

The regular data checks performed by CDM allow a quick response in case inconsistencies such as incorrect, missing or implausible information are discovered. Consequently, staff at the study sites can avoid further errors or subsequent errors. This way, a consistently high quality of data is established and sites are well prepared for the regular monitoring visits, as well as for reporting at the end of the study or for inspections. CDM can also be used to identify early on whether individual sites are having problems with a particular aspect of data collection. Such difficulties, or difficulties that occur at all sites, can then be actively addressed by the sponsor.

CDM requires close collaboration and frequent communication between the study sites and the central data monitors. In the end, however, the approach proves efficient, also because of the team spirit that sustains such a project.

A. Brehm und L. Balmer



"In my experience, Centralised Data Monitoring clearly contributes to more efficient work flows. We are able to identify early on which study sites have problems and where we need to provide help."

Alex Brehm, PhD, Research Associate DISTAL study