Scalpdex: a quality-of-life instrument for scalp dermatitis

Abstract

Objective: To develop a scalp dermatitis-specific quality-of-life instrument.

Methods: Based on the results of directed focus sessions with 8 patients with scalp psoriasis or seborrheic dermatitis, we conceptualized 3 major constructs that explain the way scalp dermatoses affect patient quality of life: symptoms, functioning, and emotions. We constructed a 23-item instrument, Scalpdex, and tested its reliability, responsiveness, and validity.

Results: Fifty-two dermatology patients completed the study. We demonstrated construct validity by confirming that the factors derived by principal axes factor analyses with orthogonal rotation correlated to our hypothesized scales (r = 0.76-0.84) and that differences in symptom, functioning, and emotion scores differed among the varying levels of self-reported scalp severity more than would be expected by chance (P<.05 by analysis of variance). The instrument demonstrated reliability with internal consistency (Cronbach alpha, 0.62-0.80) and reproducibility (intraclass correlation coefficient, 0.90-0.97). The quality-of-life scores changed in the expected direction in our test for responsiveness (P<or=.05, by paired t test for functioning and emotion for those who improved). We ascertained the discriminant capability of Scalpdex compared with a dermatological generic quality-of-life tool, Skindex, by demonstrating superior responsiveness (P<or=.005 by paired t test in functioning and emotion) and improved overall sensitivity in individual items.

Conclusions: Scalpdex is, to our knowledge, the first quality-of-life instrument specifically for patients with scalp dermatitis that is reliable, valid, and responsive. Clinicians can use the instrument to determine which aspect of the disease most bothers the patient and to evaluate quality of life as one variable of responsiveness to the therapeutic intervention.