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

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.

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.

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).

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).

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.