Dermatology Life Quality Index in Patients with Atopic Dermatitis: Are "Not Relevant" Responses Relevant?

Introduction: According to the DLQI user manual, the patients' answers "not relevant" (NR) and "not at all" (affected in this aspect of life by the skin problem) are treated equally and interpreted as no impairment in health-related quality of life (HRQoL). The aim of this study was to gain more insights about "NR" responders with atopic dermatitis (AD). Methods: A total of 3,353 patients with AD, recruited from dermatological offices and a patient organisation, were surveyed in three cross-sectional studies. Disease severity (SCORAD) and subjective health status (EQ VAS) were compared for each DLQI item between patients who answered "NR" and all others according to their response category. Different DLQI scoring versions were analysed. Results: Those who stated "NR" in terms of HRQoL limitations in the DLQI domains sports, work/study, and sexual relationships were comparable in AD severity and health status to those who felt that their HRQoL was "a little affected." Some alternative DLQI scoring versions correlated slightly higher with the SCORAD and EQ VAS than the original DLQI. Conclusion: Patients with AD who rate certain life domains as "NR" in the DLQI are most similar in their disease burden to patients who feel a little affected in these areas of life. This suggests that some HRQoL limitations are underestimated by the traditional DLQI scoring. However, different scoring solutions did not lead to substantially higher correlations with other disease burden criteria compared to the original. Therefore, the gain in validity by alternative versions is small.