To develop a reproducible photonumeric scale to assess photoprotected skin aging and to determine whether health and lifestyle factors, such as smoking, affect skin aging in photoprotected sites.Design
Using standard photographs of participants' upper inner arms, we created a 9-point photonumeric scale. Three blinded reviewers used the scale to grade the photographs. Participants answered multiple lifestyle questions.Setting
Academic outpatient dermatology clinic.Participants
Eighty-two healthy men and women aged 22 to 91 years.Interventions
A professional medical photographer took standardized photographs of each participant's upper inner arm. Participants answered standardized health and lifestyle questions.Main Outcome Measures
(1) Interobserver agreement and reproducibility using the photonumeric scale and (2) health and lifestyle factors most predictive of the degree of aging in photoprotected skin.Results
There was good blinded interobserver agreement as measured by the maximum range of disagreement scores for each participant (mean, 0.91; 95% confidence interval, 0.76–1.06). Results were reproducible. We developed a multiple regression model showing that the best model for predicting the degree of aging in photoprotected skin includes 2 variables: age and packs of cigarettes smoked per day.Conclusions
This photonumeric scale demonstrates good interobserver agreement and good reproducibility. Using this scale, the degree of aging in photoprotected skin was significantly correlated with patient age and a history of cigarette smoking. Additional studies are needed to continue garnering information regarding independent risk factors for aging of photoprotected skin.