Validation of a photonumeric wrinkle assessment scale for assessing nasolabial fold wrinkles

Reliable clinical assessment tools are needed to evaluate the effects of injectable devices and fillers. This study was designed to validate a new photonumeric wrinkle assessment scale using standardized photographic methodology to obtain reference photographs.

Multiple photographs (test set) from approximately 78 volunteer subjects with varying degrees of severity of the left/right nasolabial fold wrinkles were examined. Photographs of 18 subjects representing the full spectrum of nasolabial fold wrinkle severity were selected from the test set by a study team of three independent physicians and were classified using a six-point scale (0 = no wrinkles; 5 = very deep wrinkle, redundant fold). One representative photograph was identified by study team consensus for each of the six scale points. Photographs were randomly arranged in booklets for a second, independent, group of five physician raters to grade both left/right nasolabial fold wrinkles twice over a 2-week interval. The scale was considered valid if interevaluator reliability, as measured by intraclass correlation coefficient, was greater than or equal to 80 percent.

Intrarater reliability was significant (p < 0.001) for all five physicians and overall, with Pearson correlation coefficients greater than 92 percent in all cases. The overall weighted kappa coefficient for intrarater reliability for all five raters was 0.598 (range, 0.433 to 0.684). The overall interrater reliability kappa value was 0.525, and a high degree of interrater reliability was observed at week 1 and week 2 time points (intraclass correlation coefficient = 0.890 and 0.880, p < 0.001 for both), validating the new wrinkle assessment scale.

This study validates the new wrinkle assessment scale, which provides a reliable clinical tool for use in nasolabial fold wrinkle evaluation.