Is the DLQI appropriate for medical decision-making in psoriasis patients?

Abstract

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.

Proposal of a new scoring formula for the Dermatology Life Quality Index in psoriasis

“…The preponderance of evidence supports its validity, reliability and responsiveness in psoriasis . However, there exists a growing body of literature questioning key aspects of its validity including the lack of unidimensionality; differential item functioning; failure to capture the psychological burden of disease; scores being affected by transcultural variability; the lack of ability to assess individual HRQoL impact in terms of an individual's personal lifestyle, values and experiences (compared with the Patient‐Generated Index) and discrepancies identified between DLQI scores and health utility values …”

“…2,20 However, there exists a growing body of literature questioning key aspects of its validity including the lack of unidimensionality; 21 differential item functioning; [21][22][23][24] failure to capture the psychological burden of disease; 25 scores being affected by transcultural variability; [25][26][27] the lack of ability to assess individual HRQoL impact in terms of an individual's personal lifestyle, values and experiences (compared with the Patient-Generated Index) 28 and discrepancies identified between DLQI scores and health utility values. 29,30 As a part of this proposal, we evaluated the construct validity of DLQI-R. In terms of correlations with other core outcome measures, such as PASI, EQ-5D-3L and EQ-VAS, the DLQI-R performed better than the original DLQI.…”

A detailed analysis of ‘not relevant’ responses on the DLQI in psoriasis: potential biases in treatment decisions

“…that all items in the scale underlie the same construct) and detected that certain DLQI items are affected by external factors, such as age, gender and cultural background of patients . Another study found discrepancies between DLQI scores and time trade‐off utility values, suggesting that HRQoL in two patients with identical DLQI scores might be significantly different, while patients whose DLQI scores differ larger than the minimal clinically important difference may be equal . Considering the number of jurisdictions, in which the DLQI is used in national guidelines, including the European S3‐Guidelines on the systemic treatment of psoriasis vulgaris, the amount of patients affected worldwide may be very large.…”

“…16,20,34,[55][56][57][58][59] Another study found discrepancies between DLQI scores and time trade-off utility values, suggesting that HRQoL in two patients with identical DLQI scores might be significantly different, while patients whose DLQI scores differ larger than the minimal clinically important difference may be equal. 60,61 Considering the number of jurisdictions, in which the DLQI is used in national guidelines, including the European S3-Guidelines on the systemic treatment of psoriasis vulgaris, 7-11,62-66 the amount of patients affected worldwide may be very large. Our results, taken together with other findings in the literature, suggest that the applicability of the DLQI in the management of psoriasis patients may be called into question.…”

Measuring quality of life in dermatological care: experiences from Hungary

“…Nemzetközi kutatások korábban felvetették, hogy az életkor, a nem, a diagnózis és kulturális szempontok befolyásolhatják a kérdőíven adott válaszokat, megkérdőjelezték továbbá a kérdőív unidimenzionális voltát, és felhívták a figyelmet arra, hogy a DLQI kevéssé alkalmas a bőrgyógyászati betegségek mentális terhének kifejezésére (20). Hazai, normál populáción és psoriasisos betegek körében végzett kutatások egyaránt diszkrepanciát találtak a DLQI értékek és a hasznosság pontszámok között (21,22).…”