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Index reliable, valid in assessing postinflammatory hyperpigmentation from acne

A postacne hyperpigmentation index displayed good reliability and validity in scoring patients with skin of color and postinflammatory hyperpigmentation as a result of acne vulgaris, according to recent study results.

Researchers developed a postacne hyperpigmentation index (PAHPI) as an outcome measure for postinflammatory hyperpigmentation (PIH) after acne for patients with skin of color. Twenty-one patients with mild to severe PIH (aged 18 to 40 years; 85.7% women), including 16 African-Americans, one Hispanic and four Asians with Fitzpatrick skin type III-VI were recruited for the study. Patients completed a demographic questionnaire and the Skindex-29 quality of life questionnaire.

Six raters, who underwent training, scored each patient twice. Their scores included reliability ratings within and between raters. Validity was evaluated by comparing scores, and severity ranking was determined by an independent dermatologist.

A narrowband reflectance spectrophotometer was used to compare pigment intensity scores with each patient’s melanin index. PAHPI scores were compared with the Skindex-29 score.

Using weighted Cohen’s Kappa statistics, the average interrater reliability for number, size and intensity of PIH on 2 days displayed moderate agreement for intensity (0.43) and fair agreement for number and lesion size (0.27). When compared with clinical severity and melanin indices, total PAHPI scores were valid.

“Good correlation was achieved between the total PAHPI score and emotion subscale of the Skindex-29,” the researchers reported.

“The PAHPI is the first validated outcome measure for PIH …and should be useful in studies aimed at determining efficacy of treatments for PIH,” the researchers concluded. “It shows good reliability between and within raters and good validity when compared with global severity ranking, a melanin index, and quality-of-life index. A training program is important before using this scoring system.

“Future studies should be conducted to assess the sensitivity of the PAHPI to change over time with treatment of PIH.”

Disclosure: Amit G. Pandya, MD, and Maria Ivonne Arellano-Mendoza, MD, are members of the Pigmentary Disorders Academy and received honoraria as consultants from Galderma International.