Making the grade: Lip-volume scale shows reliability

July 1, 2008

The first validated scale for grading lip volume has proven its accuracy and robustness in a variety of tests, according to one of the scale's developers.

Key Points

International report - A new scale for grading lip volume has demonstrated accuracy, reliability and sensitivity in a recent study, making it the first validated scale for lip volume, according to one of the study's authors.

"Validated scales for grading wrinkling and aging already exist, but none for lip volume," says Ana Rossi, M.D., global medical director, Johnson & Johnson, Paris, who supports R&D activities for ColBar LifeScience Ltd.

Reasons why no one created such a scale previously probably have to do with the complexity of the task, she says.

Five-step study

The first step was to identify how many grades of lip volumes the different graders could recognize.

To facilitate this, high-resolution images from the faces of 118 subjects were used. For each subject, the database included both front and side images.

From expert rankings of these images, a nine-grade lip-volume grading scale was developed, both for superior and inferior lips, which comprised the second step - construction of the scale.

The third step was testing of the scale for intragrader reliability, or how well two measurements of the same lip image performed by the same observer agree.

Three expert graders undertook the task of grading a set of 20 lips images (which were randomly shown) three times, with an interval of at least two weeks between each grading.

The lip-volume scale proved itself to be reproducible and reliable, Dr. Rossi tells Dermatology Times.

For superior and inferior lips, 98 percent and 91 percent of graders' evaluations were in statistical agreement, respectively, with a difference of less than 0.5 points. Intragrader agreement was statistically significant in all cases (p<0.001).

As a fourth step, the grading scale was then tested for intergrader reliability, or how well two measurements of the same lip image agree when recorded by different observers. This scale was addressed by a multinational panel of expert graders (dermatologists). Each grader graded the 20 images using the scale and answered a questionnaire regarding the scale's content, convenience and acceptability.

All graders found the scale acceptable for characterizing lip volume and convenient to use, Dr. Rossi says.

The fifth step was to assess the validity of the scale, or its ability to measure what it purports to measure. Investigators compared results from clinical in vivo evaluation of lips using the printed scale versus grades assigned to photos of the same subjects by the same graders.

Additionally, researchers collected three-dimensional, profilometric images of subjects' lips and used these images to calculate the volume of subjects' superior and inferior lips.

Results

"We were pleased to learn that the correlation of our scale with the objective 3-D measurement of lip volume and the clinical evaluation were excellent," Dr. Rossi says.

Furthermore, she says the level of correlation between the nine-grade scale and a simplified five-grade scale that developers devised was surprising.

In other words, Dr. Rossi says, "If we remove four photos (representing half-point grades, namely 1.5, 2.5, 3.5 and 4.5) from the nine-photo grade scale, physicians will have the middle-grade picture in mind and will grade the same way as they do with the nine-photo scale."

Accordingly, investigators concluded that physicians could use the scale reliably to estimate lip volume in various patients and settings, such as evaluating results and longevity of lip augmentation procedures.

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