Study type: Epidemiological study (observational study)

Mobile Phone Use and Incidence of Glioma in the Nordic Countries 1979-2008: Consistency Check. epidem.

Published in: Epidemiology 2012; 23 (2): 301-307

Aim of study (acc. to author)

The time trends in the incidence of glioma in Denmark, Finland, Norway, and Sweden from 1979 to 2008 were investigated to update the results of the publication by Deltour et al. (2009). Furthermore, the observed incidence rates were compared to expected rates under various risk scenarios.

Further details

A simulation population was built up similar to the group with the highest mobile phone use (i.e. 40-59-year old men) based on the part of the Interphone study conducted in the Nordic countries. The proportion of persons who used mobile phones regularly (defined as using a mobile phone on average at least once a week over a period of at least 6 months) and the proportion of heavy users (defined as at least 1640 hours of lifetime cumulative call time) were estimated on the basis of the data of the Interphone study. Each of the 40 scenarios combined a value of relative risk (RR 0.8, 1.1, 1.2, 1.5, and 2.0) that multiplied the baseline incidence rate for all mobile phone users or for heavy users only, with different induction periods (1, 5, 10, and 15 years).

Endpoint/type of risk estimation

Type of risk estimation: (standardized incidence rate (SIR))

Exposure

Assessment

Population

Study size

Type Value
Total 35,250
Other:

population: 16 million adults aged 20 - 79 years

Statistical analysis method:

Conclusion (acc. to author)

Time trends in the incidence of glioma in the Nordic Countries did not strongly increase at any point during the period 1979 to 2008 in any country, among men, women, or any age-group. The annual percent change in incidence rates was 0.4 % (CI 0.1-0.6 %) among men and 0.3 % (CI 0.1-0.5 %) among women. Incidence rates for glioma have decreased in young men (20-39 years) since 1987, remained stable in middle-aged men (40-59 years) throughout the 30-year study period, and increased slightly in older men (60-79 years).
In simulations, following assumed relative risks for all mobile phone users combined with the induction time were incompatible with observed incidence time trends: relative risk of 2.0 for an induction time of up to 15 years; relative risk of 1.5 for up to 10 years; and relative risk of 1.2 for up to 5 years. For heavy users of mobile phones, relative risks of 2.0 for an induction time up to 5 years were also incompatible.
The authors concluded that no clear trend change in glioma incidence rates in the Nordic countries was observed. Several of the risk increases seen in previous case-control studies appear to be incompatible with the observed lack of incidence rate increase in middle-aged men. This suggests longer induction periods than currently investigated, lower risks than reported from some case-control studies, or the absence of any association.

Study funded by

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