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.
|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|
4 million person-years
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.