This study summarises the use of Cutaneous Lupus Disease Area and Severity Index (CLASI) as an outcome measure in clinical studies since its inception. We systematically searched MEDLINE, PubMed, EMBASE and Cochrane databases for papers including the term 'Cutaneous Lupus Disease Area and Severity Index' and its abbreviations up to August 2017, identifying 205 abstracts. Following shortlisting, two independent physicians critically reviewed 71 papers for data extraction. We found that a limited number of high-quality studies utilise CLASI scoring as an outcome measure. We concluded that further validation is necessary to identify the effectiveness of the CLASI score in the assessment of cutaneous lupus erythematosus (CLE) subtypes. The use of standardised core patient- and physician-reported outcome measures may reduce heterogeneity and allow comparisons between patients enrolled in clinical trials. This would improve the relevance within clinical practice where the use of CLASI is currently limited.