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Research Article
18 July 2025

Mapping Dermatology Life Quality Index with EQ-5D health utility index score in Chinese patients with moderate to severe psoriasis

Authors: Lu Jian, Xingzhi Wang, Kun Hu, Yongfang Duan, Mi Zhang, Wei Li, Pei Wang, Liang Tan, Wendong Chen https://orcid.org/0000-0002-9517-4745, Tingyin Chen [email protected], Juan Li [email protected], and Yehong Kuang [email protected]Author Info & Affiliations
Volume 14, Number 9
https://doi.org/10.57264/cer-2025-0039
PDFFormats

Abstract

Aim: To establish correlation between Dermatology Life Quality Index (DLQI) and EuroQol 5-Dimension questionnaire (EQ-5D) utility score in Chinese moderate-to severe psoriasis patients and develop mapping models for health utility prediction. Materials & methods: A total of 287 patients with moderate to severe psoriasis and at least one clinical visit with assessments for both DLQI and EQ-5D in a Chinese tertiary hospital were included. These patients were randomly split into a training set (n = 231) and a testing set (n = 56). Correlation analyses were performed to assess the relationship between DLQI (total score and item score) and EQ-5D utility index score. Twelve predictive models were developed using three statistical model approaches (ordinary least squares model, Tobit model and generalized linear model), incorporating various combinations of DLQI scores and patient characteristics (age, sex, education and comorbidities). Models were evaluated using root mean square error and mean absolute error (MAE). Results: A strong and significant correlation was found between DLQI total score and EQ-5D utility index score (r = -0.645, p < 0.001). The best-performing model, (ordinary least squares model using DLQI total score, had the lowest root mean square error (0.122) and MAE (0.076). Validation of this model in the testing set yielded a predicted utility score with an MAE of 0.072, and an MAE-to-utility ratio of 0.084, below the validation threshold of 0.1. Conclusion: DLQI scores can reliably predict health utility values, offering a useful tool for clinical decision-making and health economic evaluations. The model shows strong predictive accuracy and has potential applications in the management of msPsO in China.

Plain language summary: Understanding the relationship between skin-specific & general health measures in Chinese patients with moderate to severe psoriasis (msPsO)

What is this article about?

This study focuses on exploring the relationship between a skin-specific quality-of-life measure, called the Dermatology Life Quality Index (DLQI), and health utility, which indicates overall well-being and often measured by the EQ-5D-5L questionnaire, in Chinese patients with msPsO. By using this relationship, future studies can directly convert DLQI score to health utilities that are commonly needed to assess the cost–effectiveness of psoriasis treatments.

What were the results?

A strong link between DLQI scores and health utility was confirmed in Chinese patients with msPsO. Among the tested prediction models, ordinary least squares model had the best performance by only using DLQI total score to predict health utility.

What do the results mean?

Since DLQI has been routinely used to assess psoriasis in clinical practices, the developed prediction model from this study will allow future research to easily estimate health utility and fill the current evidence gap for health utility in Chinese patients with msPsO.

Shareable abstract

This study maps the Dermatology Life Quality Index (DLQI) to EQ-5D utility index scores in Chinese patients with moderate to severe psoriasis. A strong negative correlation (r = -0.645, p < 0.001) was found between DLQI total score and EQ utility index score. The best-performing model, an ordinary least squares model only using DLQI total score as the predictor, had the highest predictive accuracy (root mean square error: 0.122, mean absolute error: 0.076) among the tested models. The validation analysis confirmed that this developed predictive model offers a reliable tool to bridge the gap between dermatology-specific and generic quality-of-life measures.

Supplementary Material

File (supplementary materials.docx)

References

Papers of special note have been highlighted as: • of interest; •• of considerable interest
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