International prevalence of indoor tanning: a systematic review and meta-analysis.
OBJECTIVE
Indoor tanning is a known carcinogen, but the scope of exposure to this hazard is not known.


OBJECTIVE
To summarize the international prevalence of exposure to indoor tanning.


METHODS
Studies were identified through systematic searches of PubMed (1966 to present), Scopus (1823 to present), and Web of Science (1898 to present) databases, last performed on March 16, 2013. We also hand searched reference lists to identify records missed by database searches and publicly available data not yet published in the scientific literature.


METHODS
Records reporting a prevalence of indoor tanning were eligible for inclusion. We excluded case-control studies, reports with insufficient study information, and reports of groups recruited using factors related to indoor tanning. Two independent investigators performed searches and study selection. Our search yielded 1976 unique records. After exclusions, 161 records were assessed for eligibility in full text, and 88 were included.


METHODS
Two independent investigators extracted data on characteristics of study participants, inclusion/exclusion criteria, data collection format, outcomes, and statistical methods. Random-effects meta-analyses were used to summarize the prevalence of indoor tanning in different age categories. We calculated the population proportional attributable risk of indoor tanning in the United States, Europe, and Australia for nonmelanoma skin cancer (NMSC) and melanoma.


METHODS
Ever and past-year exposure to indoor tanning.


RESULTS
The summary prevalence of ever exposure was 35.7% (95% CI, 27.5%-44.0%) for adults, 55.0% (33.0%-77.1%) for university students, and 19.3% (14.7%-24.0%) for adolescents. The summary prevalence of past-year exposure was 14.0% (95% CI, 11.5%-16.5%) for adults, 43.1% (21.7%-64.5%) for university students, and 18.3% (12.6%-24.0%) for adolescents. These results included data from 406 696 participants. The population proportional attributable risk were 3.0% to 21.8% for NMSC and 2.6% to 9.4% for melanoma, corresponding to more than 450 000 NMSC cases and more than 10 000 melanoma cases each year attributable to indoor tanning in the United States, Europe, and Australia.


CONCLUSIONS
Exposure to indoor tanning is common in Western countries, especially among young persons. Given the large number of skin cancer cases attributable to indoor tanning, these findings highlight a major public health issue.
Department of Dermatology, University of California, San Francisco2Stanford University School of Medicine, Stanford, California3Department of Public Health and Primary Care, University of Cambridge, Cambridge, England.
Mackenzie R
MR
Wehner
Department of Dermatology, University of California, San Francisco4Department of Dermatology, San Francisco Veterans Affairs Medical Center, San Francisco, California.
Mary-Margaret
MM
Chren
University of California, Berkeley.
Danielle
D
Nameth
Department of Internal Medicine, John Muir Medical Center, Walnut Creek, California.
Aditi
A
Choudhry
Department of Public Health and Primary Care, University of Cambridge, Cambridge, England.
Matthew
M
Gaskins
Stanford University School of Medicine, Stanford, California.
Kevin T
KT
Nead
Department of Epidemiology and Biostatistics, University of California, San Francisco.
W John
WJ
Boscardin
Department of Dermatology, University of California, San Francisco.
Eleni
E
Linos
D001315:Australia / Q000453:epidemiology; D001505:Beauty Culture; D002170:Canada / Q000453:epidemiology; D002280:Basal Cell Carcinoma / Q000453:epidemiology / Q000209:etiology; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000209:etiology; D003357:Cosmetic Techniques / Q000706:statistics & numerical data*; D005060:Europe / Q000453:epidemiology; D006801:Humans; D008545:Melanoma / Q000453:epidemiology / Q000209:etiology; D018570:Risk Assessment; D012878:Skin Neoplasms / Q000453:epidemiology* / Q000209:etiology; D055108:Sunbathing / Q000706:statistics & numerical data*; D055107:Suntan; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014481:United States / Q000453:epidemiology