Abstract
INTRODUCTION: Discoid lupus erythematosus (DLE) is a chronic inflammatory scarring alopecia that may be accompanied by a broad range of systemic and extracutaneous comorbidities. However, the prevalence and magnitude of these associations have not been comprehensively quantified. Our objective was to systematically evaluate the prevalence and associated risk of comorbidities in patients with discoid lupus erythematosus. METHODS: We conducted a systematic review and random-effects meta-analysis in accordance with PRISMA 2020 guidelines, prospectively registered in PROSPERO (CRD420250656067). MEDLINE and Embase were searched from inception to June 2025. Observational studies reporting comorbidities in patients with DLE were included. Pooled prevalence estimates and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random-effects models. Between-study heterogeneity was assessed using the I(2) statistic. Sensitivity analyses excluding small studies (n < 50) were performed for prevalence outcomes, whereas the robustness of association analyses was assessed qualitatively owing to the limited number of contributing studies. Methodological quality was evaluated using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. RESULTS: In total, 25 studies were included. Pooled prevalence estimates indicated a high frequency of systemic lupus erythematosus (SLE) (22.0%), hypertension (24.3%), depression (38.8%), and hypothyroidism (12.4%) among patients with DLE. Sensitivity analyses showed stable prevalence estimates for SLE and hypertension, with moderate variability for hypothyroidism and depression. Meta-analyses of case-control studies demonstrated significant associations between DLE and cardiovascular disease (OR 3.85, 95% CI 1.67-8.88), hypothyroidism (OR 2.55, 95% CI 1.79-3.61), hypertension (OR 2.22, 95% CI 1.91-2.58), depression (OR 2.21, 95% CI 1.71-2.85), and anxiety (OR 2.40, 95% CI 1.40-4.11). Associations with type 2 diabetes were more modest, while smoking was not significantly associated. Most association analyses were based on a limited number of studies. CONCLUSIONS: Patients with discoid lupus erythematosus exhibit a substantial burden of systemic, cardiometabolic, endocrine, and psychiatric comorbidities. While prevalence estimates were generally consistent, associations should be interpreted cautiously owing to limited available evidence. These findings highlight the importance of comprehensive clinical assessment and multidisciplinary management of patients with DLE. TRIAL REGISTRATION: The study protocol was prospectively registered in PROSPERO (CRD420250656067).