Reliability of a standardized tool for evaluating severity of cellulite in the female posterior thigh

Abstract

Numerous products and minimally-invasive procedures are available to reduce cellulite. However, there are a limited number of tools to evaluate the effects of these interventions and some are relatively complex to implement.

Objective: This study evaluated the reliability of a standardized grading system for scoring the overall severity of cellulite on the posterior thigh. The study evaluated inter-rater and intra-rater (test/re-test) reliability of the method and engaged in an iterative process to develop a reliable method to evaluate changes in the appearance of cellulite.

Methods: There were two stages in the validation process. The first stage was an open process without evaluator training. The second stage was a more controlled process with training given and moderator involvement to review grade selections. In the first stage, inter-rater reliability was examined across five evaluators who were asked to evaluate 24 photographs (right thighs) based on a cellulite graded severity chart. During the second stage, the same photographs were examined by paired evaluators who had received additional training. Scores were independently moderated by a third person. The inter-rater reliability and intra-rater reliability over a 4-week interval were evaluated using intraclass correlation coefficients (ICCs).

Results: Twenty-four female participants (18-51 years, mean 31.68 ± 9.03 years) with a mean BMI of 29.04 ± 6.52 participated in the trial. Five female evaluators completed the initial evaluations. In stage 1, the inter-rater reliability (ICC_2,5 ) was 0.838 (95%CI:0.700-0.922) and test/retest ICC_3,1 values ranged from 0.360-0.990. In stage 2, the inter-rater reliability for 2 evaluators improved to 0.978 (95%CI:0.948-0.991), and the test/retest reliability of the moderated scoring method improved to 0.993 (95%CI:0.983-0.997).

Conclusion: The iterative process developed a simple and reliable method of rating cellulite severity, with excellent inter-and intra-rater reliability, based on evaluating images of cellulite against a standard set of graded severity images. A reliable method of assessing cellulite severity is essential for undertaking future clinical trials to evaluate cellulite treatments.

Keywords: aesthetic medicine; cellulite; skin penetration; skin structure.