Table 2

Odds ratios and 95% confidence intervals for risk of glioma in relation to mobile phone exposure*. Figures are numbers (percentages) of participants

Factor and level of exposureCases (n=966)Controls (n=1716)Odds ratio (95% CI)
Frequency of use:
Never/non-regular456 (47.2)818 (47.7)1.00
Regular508 (52.6)898 (52.3)0.94 (0.78 to 1.13)
Not known2 (0.2)0
Years since first use:
Never/non-regular456 (47.2)818 (47.7)1.00
1.5-4271 (28.1)515 (30.0)0.90 (0.73 to 1.11)
5-9170 (17.6)270 (15.7)1.04 (0.80 to 1.34)
≥1066 (6.8)112 (6.5)0.90 (0.63 to 1.28)
Not known3 (0.3)1 (0.1)
Lifetime years of use:
Never/non-regular456 (47.2)818 (47.7)1.00
0.5-4342 (35.4)623 (36.3)0.93 (0.76 to 1.14)
5-9115 (11.9)206 (12.0)0.88 (0.66 to 1.17)
≥1048 (5.0)67 (3.9)1.14 (0.74 to 1.73)
Not known5 (0.5)2 (0.1)
Cumulative hours of use§:
Never/non-regular456 (47.2)818 (47.7)1.00
≤99225 (23.3)444 (25.9)0.94 (0.76 to 1.17)
99-≤544128 (13.3)218 (12.7)0.87 (0.65 to 1.15)
>544135 (14.0)217 (12.6)0.94 (0.71 to 1.23)
Not known22 (2.3)19 (1.1)
Cumulative number of calls§:
Never/non-regular456 (47.2)818 (47.7)1.00
≤2071237 (24.7)444 (25.9)0.99 (0.80 to 1.23)
2071-≤6909102 (10.6)217 (12.6)0.70 (0.52 to 0.93)
>6909146 (15.1)218 (12.7)0.97 (0.74 to 1.28)
Not known25 (2.6)19 (1.1)
Cumulative hours of use ≥10 years ago:
Never/non-regular456 (47.2)818 (47.7)1.00
<10 years429 (44.4)772 (45.0)0.93 (0.77 to 1.13)
≥10 years, ≤113 hours23 (2.4)56 (3.3)0.61 (0.36 to 1.04)
≥10 years, >113 hours39 (4.0)54 (3.2)1.11 (0.70 to 1.75)
Not known19 (2.0)16 (1.0)
Proportion urban/rural at first use:
Never/non-regular456 (47.2)818 (47.7)1.00
Mainly urban241 (24.9)471 (27.4)0.83 (0.66 to 1.03)
Mainly rural49 (5.1)84 (4.9)0.98 (0.66 to 1.46)
Both215 (22.3)343 (20.0)1.05 (0.83 to 1.31)
Not known5 (0.5)0
According to tumour grade**
Frequency of use in those with high grade tumours:
Never/non-regular331 (50.9)818 (47.7)1.00
Regular317 (48.8)898 (52.3)0.95 (0.77 to 1.17)
Not known2 (0.3)0
Frequency of use in those with low grade tumours:
Never/non-regular122 (39.9)818 (47.7)1.00
Regular184 (60.1)898 (52.3)0.85 (0.63 to 1.13)
Not known00
According to side of phone use††
Frequency of ipsilateral use*:
Never/non-regular550 (66.3)1230 (71.7)1.00
Regular278 (33.5)486 (28.3)1.24 (1.02 to 1.52)
Not known2 (0.2)0
Frequency of contralateral use*:
Never/non-regular629 (75.8)1225 (71.4)1.00
Regular199 (24.0)491 (28.6)0.75 (0.61 to 0.93)
Not known2 (0.2)0
  • * Reference category is never or non-regular use of any type of mobile phone and, in ipsilateral analysis, phone use only on opposite side of tumour, and in contralateral analysis, phone use only on same side as tumour.

  • † Odds ratios adjusted for age at reference date (in 5 year age groups), sex, region, Townsend deprivation category, and interview reference date category.

  • ‡ Lower limit 1.5 years ago because regular phone use defined as phone use of at least six months' duration at least one year before reference date.

  • § For cumulative number and duration of calls category cut-off points were median and 75th centile of use for controls who were regular phone users.

  • ¶ Use over 10 years before reference date for controls and diagnosis date for cases.

  • ** 10 tumours (1.7%) were of undetermined grade.

  • †† In 449 (46.5%) cases tumour was classified as being on right side of head and in 387 (40.1%) on center side, 49 cases (5.1%) were excluded from this analysis because tumour was central, 81 cases (8.4%) because side of tumour was unknown, six others where side of phone use was unknown were also excluded.