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Smoking harms skin even at photoprotected sites; Degree of dermal aging significantly higher among smokers; Study limitations: Retrospective review, small sample size
"We set out not especially to examine the effects of smoking, but to produce a visual scale for evaluating sun-protected sites, because no such scale existed before," says Yolanda Rosi Helfrich, M.D., assistant professor of dermatology, University of Michigan, Ann Arbor, Mich.
With researchers increasingly analyzing what occurs in intrinsic skin aging, she says, "It's important when different centers are doing research of this sort that they have a scale that allows some uniformity."
Researchers enrolled 82 subjects ages 22 to 91, including a fairly balanced representation with respect to age and gender. Next, a professional photographer took a standardized digital photo of each participant's upper inner right arm, which is generally photoprotected and easy to photograph, Dr. Helfrich notes.
To create a photographic scale, researchers selected five participant photographs as standards to represent fine wrinkling grades of 0 (none), 2, 4, 6 and 8 (severe). Researchers selected only five standard photos because intermediate grades would have been very difficult to capture on film. They furthermore excluded the five standard photos from observer analysis.
To test inter-observer variability, researchers asked three blinded judges (two dermatology residents and one medical student) to individually grade the remaining 77 photographs using the nine-point photonumeric scale.
Researchers used a "maximum range of disagreement," Dr. Helfrich says. This required assessing the difference between the highest and lowest scores given by the graders and averaging these scores across all 77 participants, she tells Dermatology Times.
For the initial set of scores, the maximum range of disagreement among the three graders was less than one point on the photonumeric scale (95 percent confidence interval). When observers regraded the photos a year later, this figure was slightly more than one point, although this difference was not statistically significant, she says.
A survey of lifestyle factors such as smoking habits and number of children subjects had had supplemented the analysis.
When researchers stratified patient groups by age, they found that among subjects age 45 and older, the degree of photoprotected skin aging was significantly higher among smokers (Arch Dermatol. 2007;143:397-402).
For subjects ages 45 to 65, smokers' mean wrinkling grades were 1.2 points higher than those of nonsmokers, and for subjects older than 65, the difference was approximately two points.
"It's well-known that smoking is associated with multiple problems, and this study adds to that list," Dr. Helfrich says.
Dr. Helfrich says, "One always runs into potential difficulties with reporting" by patients.
Nor was the study randomized or prospective, "which is really the best way to examine the effect of smoking on the skin," she says.
For now, Dr. Helfrich says, "We didn't set out expecting any real changes in the skin of smokers," although findings here weren't completely unexpected. "Many studies show that smoking affects facial skin. We also know that the mediators of smoking seem to travel in the blood. So it makes sense that one would find increased aging in areas other than the face," she says.
Disclosure: Dr. Helfrich reports no financial interests relevant to this article.