Topic

Prospective cohort study on mobile phone users

Start

01.08.2004

End

31.05.2005

Project Management

University of Mainz / University of Bielefeld / DKFZ Heidelberg

Objective

There are few investigations available on the long-term health effects related to mobile phone use. An international prospective cohort study, the so-called COSMOS study (COHORT STUDY ON MOBILE PHONE USE AND HEALTH) has been initiated to investigate whether the frequent use of mobile phones is associated with an increased risk of various diseases (malignant tumours, heart diseases, neurodegenerative diseases, symptoms, etc.). It is planned to build up a cohort with a total of about 250.000 mobile phone users including about 50.000 persons from five countries (U.K., Sweden, Denmark, Finland, Germany). In order to test the feasibility of such a study in Germany in a first step a pilot study was conducted.

Results

• In principal the feasibility of conducting a cohort study in Germany was successfully demonstrated.
• The cohort of mobile phone users can successfully be established via subscriber lists of the four net providers (T-mobile, O2, E-Plus, Vodafone). It is possible to select participants by sex, age and exposure. The co-operation of net providers was high.
• Yearly extraction of the data on mobile phone use for a three month period from the data bases of the net providers is technically possible and can be provided if informed consent of the study participants is given.
• The legal data protection issues have been addressed on a state level as well as on a federal level. They have been incorporated in the study.
• Mortality data can be collected using death certificates. Morbidity data for cancer can be provided by cancer registries. Clinic discharge registers are not always complete and are usually not population-based. Therefore, for data collection on all diseases beside cancer as well as on adverse health effects a questionnaire is necessary.
• The international prospective cohort study will be able to detect small increases of risks even in rare diseases.
• A pilot study including 5,000 people was performed. Experiences have been made to conduct this study with inclusion of the net providers as well as without them. Both approaches are possible. In total the response rate was extremely low (about 5 % via net providers or 12% via population). In two of the other countries pilot studies had shown much higher response rates up to 43%. Next to the strong data protection laws in Germany one of the main reasons for the low response rate was the low willingness of the selected citizens to participate.

A short version of the final report in English is available as PDF-file (80 kB)

Conclusions

In principal the feasibility of conducting a cohort study in Germany was successfully demonstrated. However, there was one major limitation concerning the response rate. This was mainly due to the very restrictive requirements of the German data protection law for telecommunications. In order to build up a cohort of 50.000 people the time, effort and costs would be tremendous, since nearly one million people had to be contacted. This is not possible. Surely, there may exist some strategies to further increase the response rate (media campaigns, etc.), yet it is speculative whether it is possible to increase the response rate at least by a factor of four. This could be tested only in a second large pilot study. Due to financial reasons and the time limit of the German telecommunication research program this cannot be done within this research program. Therefore the BfS had to decide not to fund the cohort study in Germany at the moment.