Table 3.
Odds ratios and 95% confidence intervals for risk of glioma in relation to use of analogue phones
| Factor and level of exposure | Cases | Controls | Odds ratio (95% CI) |
|---|---|---|---|
| Frequency of use*: | |||
| Never/non-regular | 456 (47.2) | 818 (47.7) | 1.0 |
| Digital only | 378 (39.1) | 685 (39.9) | 0.96 (0.79 to 1.16) |
| Regular analogue | 128 (13.3) | 212 (12.4) | 0.87 (0.66 to 1.15) |
| Not known | 4 (0.4) | 1 (0.1) | — |
| Years since first use: | |||
| Never/non-regular | 456 (47.2) | 818 (47.7) | 1.0 |
| Digital only | 378 (39.1) | 685 (39.9) | 0.96 (0.79 to 1.16) |
| 1.5-4† | 15 (1.6) | 33 (1.9) | 0.59 (0.30 to 1.15) |
| 5-9 | 56 (5.8) | 84 (4.9) | 0.98 (0.66 to 1.45) |
| ≥10 | 56 (5.8) | 95 (5.5) | 0.87 (0.59 to 1.27) |
| Not known | 5 (0.5) | 1 (0.1) | — |
| Lifetime years of use: | |||
| Never/non-regular | 456 (47.2) | 818 (47.7) | 1.0 |
| Digital only | 378 (39.1) | 685 (39.9) | 0.96 (0.79 to 1.16) |
| 0.5-4 | 90 (9.3) | 159 (9.3) | 0.82 (0.60 to 1.11) |
| 5-9 | 27 (2.8) | 42 (2.4) | 0.97 (0.57 to 1.66) |
| ≥10 | 10 (1.0) | 11 (0.6) | 1.20 (0.48 to 3.04) |
| Not known | 5 (0.5) | 1 (0.1) | — |
| Cumulative hours of use ≥10 years ago‡: | |||
| Never/non-regular | 456 (47.2) | 818 (47.7) | 1.0 |
| Digital only | 378 (39.1) | 685 (39.9) | 0.95 (0.79 to 1.16) |
| <10 years | 69 (7.1) | 115 (6.7) | 0.86 (0.61 to 1.22) |
| ≥10 years, ≤126 hours | 23 (2.4) | 47 (2.7) | 0.70 (0.41 to 1.21) |
| ≥10 years, >126 hours | 31 (3.2) | 47 (2.7) | 0.98 (0.59 to 1.62) |
| Not known | 9 (0.9) | 4 (0.2) | — |
*
Of 4055 phones reported by participants, 586 (14.5%) were analogue, 3183 (78.5%) were digital, and 286 (7.1%) could not be classified.
†
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.
‡
Use ≥10 years before reference date for controls and diagnosis date for cases.