Creating a database and pooled analysis


Mirta Milic


Stefano Bonassi

MC Members:

Carla Costa, Diana Anderson, Elke Richling, Gudrun Koppen, Katarina Volkovova, Pavel Rossner, Peter Eckl, Peter Moller, Roger Godschalk, Solange Costa, Stefano Bonassi, Vanessa Valdiglesias

Non MC Members:

Cristiana Costa Pereira, Malzorgata Dobrzynska, Monica Neri

The group is responsible in creating the templates for collecting data from the 51 laboratories worldwide who agreed to participate and to create combined database. Every lab will receive invitation letter, template for the method details, and template for the study details and excel worksheet template for comet assay data. The data will be entered into a unified database compatible with the statistics software to be used for the analysis.This working group is also responsible for pooled analysis of comet assay data in order to obtain definitive information on the reasons for inter-individual variation in levels of DNA damage. The collected data in the unified database will be subjected to a pooled analysis using STATA statistical software, to assess the influence of variations in practical procedures on the level of damage detected, and to determine the relationships between DNA damage and age, sex, lifestyle, nutrition, smoking etc.


  1. Participants contacted and spreadsheets sent (month 6)
  2. Data received and unified database created (month 12)
  3. Database checked for compatibility with statistics software (Month 13)
  4. Completion of statistical analysis of pooled data (Month 24)


  1. Database for use in pooled analysis (month 12)
  2. Publication reporting on technical factors influencing comet assay results (Month 30),
  3. Publication reporting on influence of age, sex, lifestyle, nutrition, smoking etc. on DNA damage levels.(Month 36)

Second Year of the Project

Goal: Completion of database and pooled analysis of data; relates to Objectives 1, 2, 3


M1.3. Database checked for compatibility with statistics software (Month 13) 

M1.4. Completion of statistical analysis of pooled data (Month 24)


D1.2. Training course: Statistical approaches to molecular epidemiology (year 2)

D1.3 The group has been responsible for collecting data from the 51 laboratories worldwide who agreed to participate and to create a combined database. This database is now complete, with almost 20 000 individual datasets from different studies. It records information about the studies, the type of the cells tested, practical details concerning performance of the comet assay, measurements of basal DNA strand breaks, and, in many cases, also measurements of base oxidation, antioxidant status, and DNA repair capacity. The pooled analysis now in progress will obtain definitive information on the causes (both technical and biological) of variations in levels of DNA damage and repair between laboratories and within populations.


Creating a database. A questionnaire has already been circulated by the ComNet project to researchers identified as performing biomonitoring with the comet assay, to collect information on:

1) Extent of experience of researcher with the assay,

2) Type of human samples studied,

3) Versions of comet assay used,

4) Kind of human biomonitoring study,

5) Kind of data collected on subjects (anthropometric, health-related, dietary, genetic),

6) Which comet assay parameters are collected? hCOMET will have access to this information and will take on the role of collecting the data. The questionnaire is still 'open', but some provisional statistics are given below.

Research activity:

Applying comet assay to PBMN cells - 72%

Using standard comet assay (for DNA strand breaks) - 89%

Using comet assay + FPG (for oxidised bases) - 64%

Measuring H2O2 resistance (antioxidant status) - 30%

Measuring DNA repair - 49%

Studying occupational exposure - 49%

Studying environmental exposure - 43%

Studying nutrition - 32%

Judging by the responses to the questionnaire, the Action aims at collecting anonymised data from human biomonitoring studies carried out in over 50 laboratories, representing more than 19,000 subjects, from many countries, mainly in Europe. These studies include prospective/ cohort, cross-sectional and intervention studies, case-control studies of various diseases, investigations of occupational and environmental exposure to xenobiotics, nutritional studies, examinations of age-related effects, sex differences, etc. Such a database can only be set up with close collaboration of individual, nationally funded researchers within a pan-European network.

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