Study type: Epidemiological study (observational study)

Mobile phones and multiple sclerosis - a nationwide cohort study in denmark. epidem.

Published in: PLoS One 2012; 7 (4): e34453

Aim of study (acc. to author)

The risk of multiple sclerosis as well as prognosis and symptoms among all Danish residents who owned a mobile phone subscription before 1996 were investigated in a cohort study.

Further details

Private mobile phone subscription holders were identified from subscriber lists of two Danish operating companies. The incidence of multiple sclerosis was determined by linkage via the personal identification number with the Danish Multiple Sclerosis Registry.

Endpoint/type of risk estimation

Type of risk estimation: (incidence and mortality rate ratios)

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 non subscribers
Group 2 subscription holders
Group 3 years of subscription: < 1 year
Group 4 years of subscription: 1 - 3 years
Group 5 years of subscription: 4 - 6 years
Group 6 years of subscription: 7 - 9 years
Group 7 years of subscription: 10 - 12 years
Group 8 years of subscription: ≥ 13 years

Population

Study size

Type Value
Total 723,421
Eligible 420,086
Other:

4 million person-years

Statistical analysis method:

Conclusion (acc. to author)

In the Danish nationwide cohort study of mobile phone subscription holders, no overall increased risk of multiple sclerosis or of death was found among subscription holders. Among subgroups of women, some risk increases of multiple sclerosis, symptoms and death after long-term subscription were found, however, the numbers were small in these analyses and may have been chance findings.
The first symptoms of multiple sclerosis were different among mobile phone users compared to non-subscribers, with subscription holders having more frequent fatigue among women, increased optic neuritis among men, and diplopia in both sexes.
The authors concluded that they found little evidence for a pronounced association between mobile phone use and risk of multiple sclerosis or mortality among multiple sclerosis patients. Symptoms of multiple sclerosis differed between subscribers and nonsubscribers. This deserves further attention, although small numbers and lack of consistency between genders prevent causal interpretation.

Study funded by

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