What is it? Why is it important?

Central Data Monitoring (CDM) is a central review of the accumulating data in the study database.

The monitor remotely accesses and evaluates study data. This is only possible when data is captured electronically (e-CRF). A data scientist, a statistician, or medical reviewer can also perform CDM.


CDM that often includes statistical data analysis (called central statistical monitoring) can be used to identify:

  • Missing, implausible, or inconsistent data
  • Unexpected or false data (e.g. outliers)
  • Systematic errors in data collection
  • Trends and inconsistencies (e.g. an unexpected lack of variability)
  • Variability within and across sites (e.g. identification of sites with high error rates, relatively high or low number of (serious) adverse events, low participant recruitment)
  • Study protocol deviations (e.g. changes in participant visit schedules, specific tests, or medical examinations that were not – or only partly – performed)
  • Deviations from database completion requirements (e.g. entry must be done within 5 days after participant visit)


Sites with poor performance or problematic issues detected during centralised monitoring might best be solved by performing an on-site visit.


In a multicentre study, 4 of the 5 participating sites reported headaches in at least 30% of the participants. At one site with 50 participants, no headaches were reported. This raises concerns regarding site adherence to study safety reporting requirements. This issue, which was detected remotely, may trigger on-site visits to investigate the root cause and to impose corrective measures.

What do I need to do?

As a SP-INV, define CDM tasks such as:

  • Study data checks that can be performed in the study database, such as data completeness, plausibility, consistency checks, including checks for outliers such as unexpected data based on its normal distribution
  • Checks of important data (e.g. data related to the primary endpoint)
  • The statistical monitoring approach with support from a statistician. Especially in multicentre studies, inter-site comparisons can provide additional information



  • CDM can be more cost-effective, as it can be used to complement and thereby reduce the extent and/or frequency of on-site monitoring
  • Is particularly important in multicentre studies as it helps keeping oversight regarding the conduct and performance at study sites. The implementation of CDM is thus highly recommended in large multicentre studies
  • Strategy and checks should be specified in a CDM plan and documented in CDM reports


For more information refer to Data Handling in this Study Guide

Where can I get help?

Your local CTU can support you with experienced staff regarding this topic


ICH GCP E6(R2) – see in particular guidelines

  • 5.18 Monitoring activities
  • 6.10 Access to source data / documents

ISO 14155 Medical Device – see in particular section (access liable to costs)

  • 7.8 Document and data control
  • 9.2.4 Monitoring


  • CDM – Central Data Monitoring
  • CDMS – Clinical Data Management System
  • CTU – Clinical Trials Unit
  • DOB – Date of Birth
  • EC/RA – Ethics Committee / Regulatroy Authorities
  • eCRF – electronic Case Report Form
  • ICH GCP – International Council for Harmonisation Good Clinial Practice
  • IMP/MD – Investigational Medicinal Product / Medical Device
  • ISO – International Organisation for Standardisation
  • ICF – Informed Consent Form
Development ↦ Monitoring ↦ Montoring Strategy ↦ Central Data Monitoring

Provides some background knowledge and basic definitions

Basic Monitoring
Basic Drug or Device

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Drug or Device

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Drug or Device

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Ethics and Laws
Set-Up Quality and Risk
Set-Up Drug or Device

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Drug or Device

Starts with last study visit completed

Ends after study publication and archiving

Completion Statistics
Completion Drug or Device
Current Path (click to copy): Development ↦ Monitoring ↦ Montoring Strategy ↦ Central Data Monitoring

Please note: the Easy-GCS tool is currently under construction.