Table 2.
Outcome effect sizes for studies included in primary meta-analysis
| Reference | Odds ratio (95% CI) | Adjustments | |
|---|---|---|---|
| Basal cell carcinoma | Squamous cell carcinoma | ||
| Studies comparing ever exposure with indoor tanning to never exposure | |||
| Asgari et al14 | — | 1.41 (0.90 to 2.22) | None (crude) |
| Aubry and McGibbon15 | — | 13.42 (1.38 to 130.48) | Age, sex, eye and hair colour, skin type*, ethnicity, sun exposure† |
| Bajdik et al16 | 1.2 (0.7 to 2.2) | 1.4 (0.7 to2.7) | Age, (sex‡), hair colour, skin type*, ethnicity, sun exposure† |
| Corona et al19 | 0.6 (0.3 to 1.2) | — | Age, sex, skin type*, sun exposure†, family history of skin cancer |
| Ferrucci et al20 | 1.69 (1.15 to 2.48) | — | Age, sex, body site, skin type*, sun sensitivity§, family history of skin cancer, melanocortin 1 receptor gene non-synonymous variants |
| Gon and Minelli21 | 0.31 (0.07 to 1.35) | — | Age, sex, eye colour, hair colour, skin type*, family history of skin cancer, presence of actinic keratosis |
| Han et al22 | 1.32 (0.87 to 2.03) | 1.44 (0.93 to 2.24) | Age, (sex‡), sun exposure†, sun sensitivity§, history of severe sunburns¶, geography**, family history of skin cancer |
| Karagas et al25 | 1.5 (1.1 to 2.1) | 2.5 (1.7 to 3.8) | Age, sex, sun sensitivity§†† |
| Rosso et al27 | 1.24 (0.53 to 2.88) | — | Age, sex |
| Zhang et al29 | 1.29 (1.22 to 1.35)‡‡ | 1.50 (1.20 to 1.78)‡‡ | Age, (sex‡), hair colour, sun exposure†, sun sensitivity§, history of severe sunburns¶, geography**, number of moles on legs, family history of melanoma |
| Studies measuring higher dose exposure: “regular” exposure17 or >5 exposures per year28 | |||
| Bakos et al17 | 25.0 (2.26 to 277.36) | — | Sunscreen use, parents’ sunscreen use, smoking |
| Walther et al28 | 0.7 (0.3 to 1.5) | — | None (crude) |
*Skin type: complexion (Aubry and McGibbon), skin colour (Bajdik et al, Ferrucci et al), pigmentary traits (Corona et al).
†Sun exposure: non-occupational sun exposure (Aubry and McGibbon), lifetime occupational sun exposure (Bajdik et al), number of weeks spent at beach before age 20 and outdoor work (Corona et al), cumulative sun exposure while wearing bathing suit (Han et al), outdoor sun exposure (Zhang et al).
‡Study not adjusted for sex because only included one sex.
§Skin sensitivity to sun: skin response to first exposure of season to 1 hour of summer sun and to prolonged exposure to sun (Ferrucci et al), constitutional susceptibility score (Han et al), sun sensitivity (Karagas et al), childhood tendency to sunburn (Zhang et al).
¶History of severe sunburns: lifetime sunburns which blistered (Han et al), number of severe sunburns between 15 and 20 (Zhang et al).
**Geography: geographic region at baseline (Han et al), ultraviolet index in area of residence at birth and 15 and 30 years of age (Zhang et al).
††Adjusted for age and sex in basal cell carcinoma analysis because adjustment for sun sensitivity did not change results.
‡Hazard ratio (95% CI), obtained directly from authors.