Epidemiologic determinants of skin photoaging: baseline data of the SU.VI.MAX. cohort

Although skin disorders associated with long-term sun exposure account for high morbidity, only few data on sun-related preclinical skin changes are available in the general population.

In the present study we determined reference values for markers of photoaging in French adults, and we evaluated the relationship between photoaging, phototype, and both behavioral and environmental factors.

The SU.VI.MAX trial is a multicenter, national intervention trial on 12,735 adults living in France. A transverse analysis was performed on the inclusion data of the sample of volunteers between 45 and 60 years of age who underwent skin evaluation in 1995: 3057 women and 3606 men. Skin was evaluated by means of the Larnier skin photoaging photographic scale and a sun reactive skin type classification derived from those proposed by Fitzpatrick in 1976 and Césarini in 1977.

The prevalence of skin photoaging, assessed as a dichotomous variable (from moderate/severe to very severe), was comparable in men and women in same age groups: in women, age group 45-49 years = 22%, 50-54 years = 36%, and 55-60 years = 42%; in men, age group 45-49 years = 17%, 50-54 years = 38%, and 55-60 years = 45%. After adjusting for body mass index, exposure to tobacco, and sunlight exposure, the only variables found to be related to skin photoaging in women were age (55-60 years age group: adjusted odds ratio [AOR] = 6.0, 95% confidence interval [CI] = 4.4-8.2), phototype IIIa, IIIb, and IV (AOR = 0.2, 95% CI = 0.1-0.4; AOR = 0.3, 95% CI = 0.2-0.6; and AOR = 0.4, 95% CI = 0.3-0.8; respectively), menopausal status (AOR = 1.4, 95% CI = 1.1-1.9), and geographic location (Southern France: AOR = 0. 7, 95% CI = 0.6-0.9), with a more pronounced effect in lighter phototypes I-II and a protective impact related to southern locations. No relationship was found between the use of oral contraceptives and skin photoaging. The age effect was also found in men (55-60 years age group: AOR = 10.4, 95% CI = 8.3-13.1) and geographic location (Southern France: AOR = 0.8, 95% CI = 0.6-0.9), with a most pronounced effect in darker phototypes (phototypes > IV: AOR = 2.8, 95% CI = 1.4-5.6).

Our results suggest that the prevalence of skin photoaging in the adult French population is determined by age, sex, geographic location, and phototype. The continuation of this longitudinal study will allow for the investigation of the relationship between skin photoaging and the risk of the development of skin diseases.