Dermatology Life Quality Index (DLQI) is the most common health-related quality of life measure in dermatology that is widely used in treatment guidelines for psoriasis. Eight out of the 10 questions of the DLQI offer a ‘not relevant’ response (NRR) option that is scored as the item had no impact on patients’ life at all. We aim to explore the occurrence of NRRs on the DLQI in psoriasis patients and to examine the effect of several socio-demographic and clinical factors on giving NRRs. Data were obtained from two cross-sectional surveys among 428 psoriasis patients in Hungary. Health-related quality of life was measured by employing DLQI and EQ-5D-3L, while disease severity was graded by Psoriasis Area and Severity Index (PASI). Mean age of the patients was 49 years, and 65% were males. Mean PASI, DLQI and EQ-5D-3L index scores were 8.4±9.5, 6.8±7.4 and 0.74±0.28, respectively. Overall, 38.8% of the patients had at least one NRR: 19.6% (one), 11.5% (two), 5.1% (three) and 2.6% (more than three). Most NRRs occurred in sport, sexual difficulties and working/studying items (28.4%, 16.4% and 14.0%, respectively). Patients with higher DLQI or PASI scores and lower EQ-5D-3L scores provided more NRRs (p<0.05). Women, older, less educated and those with no full-time job more frequently tended to tick a NRR (p<0.01). The high rate of psoriasis patients with NRRs and the inverse association between the DLQI and PASI scores and the number of NRRs indicate a content validity problem of the measure. As the DLQI is used in medical and financial guidelines for biological therapy, women, less educated and elderly patients might be at a disadvantage in receiving treatment.

Women, elderly and less educated psoriasis patients provide more 'not relevant' responses on the Dermatology Life Quality Index - is it a problem?