The Dermatology Life Quality Index as the primary outcome in randomized clinical trials: a systematic review

Abstract

Background Primary endpoint measures in clinical trials are typically measures of disease severity, with patient reported outcome measures (PROMs) relegated as secondary endpoints. However validation of some PROMs may be more rigorous than that of disease severity measures, arguing for a primary role for PROMs. Objectives This study reports on 24 peer reviewed journal articles that used the Dermatology Life Quality Index (DLQI) as primary outcome, derived from a systematic review of randomised controlled trials (RCTs) utlising DLQI covering all diseases and interventions. Materials and Method The study protocol was prospectively published on the PROSPERO database, and the study followed PRISMA guidelines. Searches were made with Medline, Cochrane library, EMBASE, Web of Science, SCOPUS, CINAHL(EBSCO) and PsycINFO databases and records combined into an Endnote database. Records were filtered for duplicates and selected by study inclusion/exclusion criteria. Full text articles were sourced and data was extracted by two reviewers into a bespoke REDCap database, with a third reviewer adjudicating differences. The Jadad scoring method was used to determine risk of bias. Results Of the 3,220 publications retrieved from online searching, 457 articles met eligibility criteria and included 198,587 patients. DLQI scores were primary outcomes in 24 (5.3%) of these studies comprising 15 different diseases and 3,436 patients. Most study interventions (17/24 studies, 68%) were systemic drugs with biologics (liraglutide, alefacept, secukinumab, ustekinumab, adalimumab) accounting for five out of 25 pharmacological interventions (20%). Topical treaments comprised 32% (8 studies) whereas non-pharmacological interventions (8) were 24% of the total interventions (33). Three studies used non-traditional medicines. Eight studies were multicentred (33.3%), with trials conducted in at least 14 different countries, and four (16.7%) were conducted in multiple countries. The Jadad risk of bias scale showed that bias was uncertain or low, as 87.5% of studies had Jadad scores of ≥3. Conclusions This study provides evidence for use of the DLQI as primary outcome in clinical trials to inform researchers’ and clinicians’ decisions for its further use.