The high rate of psoriasis patients with NRRs, especially among women, less educated and elderly patients, indicates a content validity problem of the measure. A reconsideration of the use of the DLQI for medical and financial decision-making in psoriasis patients is suggested.

The DLQI-R seems to be a valid scoring system for avoiding the bias in the NRR option and can help to improve patients' access to biologics.

The EQ-5D-5L seems to improve measurement properties by reducing ceiling effects, strengthening correlations with PASI and improving informativity. Follow-up studies are needed to test responsiveness and reliability in psoriasis.

Background The Dermatology Life Quality Index (DLQI) rates 'not relevant' responses (NRRs) as the item on the questionnaire having no impact on the patients' lives at all. The DLQI-Relevant (DLQI-R) is a recently developed scoring that adjusts the total score of the questionnaire for the number of NRRs indicated by a patient. Objectives To compare the discriminatory power of the original and DLQI-R scoring approaches in terms of absolute and relative informativity. Methods Cross-sectional data from 637 patients with morphea, pemphigus and psoriasis were used for the analyses. To assess absolute and relative informativity, Shannon's index and Shannon's evenness index were calculated for the 10 items on the questionnaire and for DLQI and DLQI-R total scores. Results Mean DLQI and DLQI-R scores of patients were 6Á13 vs. 6Á91. In the subset of patients with NRRs (n = 261, 41%), absolute informativity was higher with the DLQI-R scoring for all eight items with NRR options in all three conditions. The DLQI-R exhibited a better relative informativity in 8, 8 and 6 items in pemphigus, morphea and psoriasis, respectively. The DLQI-R led to an improvement in average item-level informativity in all DLQI score bands up to 20 points. Regarding total scores, the DLQI-R produced both a higher absolute and relative informativity in all three conditions. Conclusions In patients with morphea, pemphigus and psoriasis, DLQI-R scoring improves the discriminatory power of the questionnaire by benefiting from the additional information in NRRs. DLQI-R scoring may be useful both in clinical practice and research. A scoring chart has been developed to aid physicians with scoring.What's already known about this topic?• The original scoring of the Dermatology Life Quality Index (DLQI) rates 'not relevant' responses as the item of the questionnaire having no impact on the patients' lives at all.• DLQI-Relevant (DLQI-R) is a new scoring developed in 2018 that adjusts the total score of the questionnaire for the number of 'not relevant' responses indicated by patients.• The discriminatory power of the DLQI-R compared with the DLQI has not yet been investigated.

Dermatology Life Quality Index (DLQI) is the most commonly applied measure of health-related quality of life (HRQoL) in psoriasis patients. It is among defining criteria of moderate-to-severe psoriasis and present in treatment guidelines. Our objective was to estimate preference-based HRQoL values (i.e., utilities) for hypothetical health states described by the 10 items of the DLQI in psoriasis patients. Moreover, we compare results to findings of a similar study previously conducted among the general public. A cross-sectional survey was carried out among 238 psoriasis patients. Seven hypothetical DLQI-defined health states with total scores of 6, 11, and 16 (3-3 and 1 states, respectively) were evaluated by time trade-off method. The difference in DLQI scores between hypothetical health states was set at 5 points, as it exceeds the minimal clinically important difference (MCID). Utility scores were found to be homogenous across the seven hypothetical health states (range of means for the 6-point states 0.85-0.91, range of means for the 11-point states 0.83-0.85, and mean of 0.84 for the 16-point state). Overall, mean utilities assessed by psoriasis patients were higher for all seven states compared with the general public (mean difference 0.16-0.28; p < 0.001). In 11 out of the 15 comparisons between health states with DLQI scores differing larger than the MCID, there was no statistically significant difference in utility. Thus, in clinical settings, patients with DLQI scores differing more than the MCID may have identical HRQoL. Improving the definition of moderate-to-severe disease and reconsideration of the DLQI in clinical assessment of psoriasis patients are suggested.