Proposal of a new scoring formula for the DLQI in psoriasis F. Rencz1,2, L. Gulácsi1, M. Péntek1, A.K. Poór3, M. Sárdy3, P. Holló3, A. Szegedi4,5, É. Remenyik4, V. Brodszky1 1 – Department of Health Economics, Corvinus University of Budapest, Budapest, Hungary 2 – Hungarian Academy of Sciences, Premium Postdoctoral Research Programme, Budapest, Hungary 3 – Department of Dermatology, Venereology and Dermatooncology, Faculty of Medicine, Semmelweis University, Budapest, Hungary 4 – Departments of Dermatology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary 5 – Department of Dermatological Allergology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary British Journal of Dermatology. DOI: 10.111/bjd.16927

Lead author: Dr Fanni Rencz Department of Health Economics, Corvinus University of Budapest, Budapest, Hungary Hungarian Academy of Sciences, Premium Postdoctoral Research Programme, Budapest, Hungary

Introduction - What’s already known? ‘Not relevant’ responses (NRRs) on the Dermatology Life Quality Index (DLQI) may occur in up to 40% of psoriasis patients. NRRs are scored as the item had no impact on patients’ life at all, it is more difficult for these patients to fulfil the DLQI>10 required by guidelines to become candidates for systemic treatment including biologics.

Objective We propose a new scoring for the DLQI that corrects for the bias in the NRR option and test its construct validity in a sample of psoriasis patients.

Methods: study population Data of patients with psoriasis from two earlier cross-sectional surveys in Hungary have been reanalysed. Psoriasis patients not treated with biological drugs were included in this analysis. General health-related quality of life was measured by the EQ-5D- 3L and EQ visual analogue scale (EQ VAS). Dermatologists provided data on the clinical characteristics of patients and graded disease severity by Psoriasis Area and Severity Index (PASI).

Methods: Dermatology Life Quality Index (DLQI) DLQI is the most commonly used health-related quality of life measure in psoriasis patients. It consists of 10 questions that can be categorised into the following six subscales: symptoms and feeling, daily activities, leisure, work and school, personal relationships and treatment. The 10 items of the questionnaire are rated on a four-point scale (‘not at all’ or ‘not relevant’=0, ‘a little’=1, ‘a lot’=2 and ‘very much’=3), yielding a total score of 0-30, where a higher score represents a greater impairment in life quality.

Methods: New scoring of the DLQI (DLQI-R) DLQI-R =DLQI× 10 10−NRR , where NRR= ’ not relevant’ response Number of NRRs DLQI-R score 1 DLQI × 10/9 = DLQI × 1.11 2 DLQI × 10/8 = DLQI × 1.25 3 DLQI × 10/7 = DLQI × 1.43 4 DLQI × 10/6 = DLQI × 1.67 5 DLQI × 10/5 = DLQI × 2 6 DLQI × 10/4 = DLQI × 2.5 7 DLQI × 10/3 = DLQI × 3.33 8 DLQI × 10/2 = DLQI × 5 For example, patients with a DLQI total score of nine ticked two NRRs; thus, their DLQI-R score would be 9×[10/(10-2)]=11.3.

Results N=242 patients, 60% males, mean age 49.8 (SD 15.4) years, mean PASI score 12.3 (SD 9.9) The DLQI-R scoring allowed eight more patients (3.3% of the total sample and 7.7% of the subsample of patients with NRRs) to achieve the ‘PASI>10 and DLQI>10’ threshold Variables n (%) DLQI DLQI-R Mean (SD) DLQI (0-30) PASI>10 and DLQI>10 (n, %) Mean (SD) DLQI-R PASI>10 and DLQI-R>10 (n, %) Total sample 242 9.99 (7.52) 77 (31.8%) 10.98 (8.02) 85 (35.1%) Patients with NRRs 104 9.49 (5.83) 36 (34.6%) 11.79 (7.16) 44 (42.3%)

Results: Proportions of DLQI and DLQI-R scores according to Hongbo’s banding system

Results: Correlation analysis In terms of correlations with other core outcome measures, such as PASI, EQ-5D-3L and EQ VAS, the DLQI-R performed better compared to the original DLQI. Outcome measures Total sample (n=242) Patients with NRRs (n=104) DLQI DLQI-R DLQI (0-30) - 0.982 0.970 PASI (0-72) 0.571 0.585 0.468 0.480 EQ-5D-3L index (-0.594-1) -0.542 -0.580 -0.523 -0.555 EQ VAS (0-100) -0.345 -0.371 -0.308 -0.363 p<0.01 for all correlation coefficients

Discussion: Psychometric testing The DLQI-R demonstrated a better convergent validity compared to the original DLQI. Aside from the rare times when total DLQI score decreases along with an increase in the number of NRRs, responsiveness properties of the DLQI-R are expected to improve, compared with the DLQI. In future studies, psychometric properties of the DLQI-R are suggested to be confirmed using previously collected longitudinal data, preferably from a randomized controlled trial.

Discussion: Guidelines and regulatory implications The literature suggests that more strict PASI and DLQI criteria in national guidelines may be responsible for the limited access to biologics. As the DLQI-R scoring is specifically proposed to be used in treatment decisions, professional societies and authors of guidelines at European as well as national level might consider allowing or disallowing the DLQI-R formula under their own authority. A maximum of three NRRs is suggested to be allowed, until further psychometric evidence is available.

Discussion: Extrapolation of the DLQI-R scoring formula to other conditions Given the DLQI is not a psoriasis-specific but a skin-specific quality of life measure, the DLQI-R scoring approach theoretically may be used in any dermatological diagnosis. Demonstrating the validity of DLQI-R is necessary in these conditions too. The DLQI-R may be extrapolated to other conditions in which treatment guidelines specify DLQI thresholds similarly to psoriasis. For example, oral alitretinoin is recommended for adult patients with severe chronic hand eczema having a DLQI score of ≥15 in the UK.

Conclusions- What does this study add? This study proposes a new scoring for the DLQI that corrects for the bias in the ‘not relevant’ response option and demonstrates its construct validity in a sample of psoriasis patients. The new scoring can help to improve patients’ access to biologics.

Research team Corvinus University of Budapest, Department of Health Economics Semmelweis University, Department of Dermatology, Venereology and Dermatooncology Dr Fanni Rencz Dr Adrienn K. Poór Dr Valentin Brodszky Dr Péter Holló Prof László Gulácsi Prof Miklós Sárdy Prof Márta Péntek University of Debrecen, Departments of Dermatology Prof Éva Remenyik Prof Andrea Szegedi

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