A systematic review of 457 randomised controlled trials using the Dermatology Life Quality Index: experience in 68 diseases and 42 countries

Abstract Background Over 29 years of clinical application, the Dermatology Life Quality Index (DLQI) has remained the most used PRO in dermatology due to its robustness, simplicity and ease of use. Objectives This systematic review aimed to generate further evidence of its utility in randomised controlled trials and is the first to cover all diseases and interventions. Methods The methodology followed PRISMA guidelines and included seven bibliographic databases, searching articles published from January 1 1994 until November 16, 2021. Articles were reviewed independently by two assessors, and an adjudicator resolved any opinion differences. Results Of 3220 screened publications, 457 articles meeting eligibility criteria for inclusion, describing research on 198,587 patients, were analysed. DLQI scores were primary endpoints in 24 (5.3%) of studies. Most studies were of psoriasis (53.2%), although 68 different diseases were studied. Most study drugs were systemic (84.3%), with biologics 55.9% of all pharmacological interventions. Topical treatments comprised 17.1% of total pharmacological interventions. Non-pharmacological interventions were 13.8% of the total interventions, mainly laser therapy and UV treatment. 63.6% of studies were multicentre, with trials conducted in at least 42 different countries, and 41.7% were conducted in multiple countries. Minimal importance difference (MID) was reported in analysis of 15.1% of studies, but only 1.3% considered full score meaning banding of DLQI. 61 (13.4%) of studies investigated statistical correlation of DLQI with clinical severity assessment or other PRO/QoL tools. 62% to 86% of studies had within group scores differences greater than the MID in “active treatment arms”. The JADAD risk of bias scale showed that bias was generally low, as 91.4% of studies had JADAD scores of ≥3; only 0.44% of studies showed high risk from randomisation, 13.8% high risk from blinding and 10.4% high risk from unknown outcome of all participants in the studies. 18.3% of studies declared that they followed an intention-to treat (ITT) protocol, and imputation for missing DLQI data was used in 34.1% of studies. Conclusions This systematic review provides a wealth of evidence for use of the DLQI in clinical trials to inform researchers’ and clinicians’ decision for its further use. Recommendations are also made for improving the reporting of data from future RCT trials using DLQI.