The impact of comorbidity on clinical characteristics in adult IgA vasculitis

Aim: Adult immunoglobulin A (IgA) vasculitis is a rare small-vessel vasculitis with heterogeneous systemic involvement and variable clinical trajectories. However, the influence of comorbidities on disease phenotype and early clinical presentation in adults remains unclear. This study aimed to determine how comorbidity burden relates to baseline clinical manifestations in adult IgA vasculitis.

Materials and Methods: In this retrospective, single-center study, we analyzed 57 adults diagnosed with IgA vasculitis between January 2017 and August 2025. Comorbidity burden was assessed using the Charlson Comorbidity Index (CCI), age-adjusted Charlson Comorbidity Index (ACCI), and Elixhauser Comorbidity Index (ECI). Patients were categorized by the presence or absence of comorbid conditions, and demographic, clinical, and laboratory characteristics were compared. Associations between organ involvement and comorbidity indices were also evaluated.

Results: Overall, 45.6% of patients had at least one comorbidity, most commonly hypertension and diabetes mellitus. Patients with comorbidities were significantly older (p<0.001) and more frequently female (50.0% vs. 22.6%; p=0.031). Gastrointestinal involvement (64.5% vs. 34.6%; p=0.025) and arthritis (61.3% vs. 23.1%; p=0.004) were more prevalent among patients without comorbidities, whereas the frequency of renal involvement did not differ significantly between groups (p=0.598). No significant correlations were observed between comorbidity indices and organ-specific involvement. In multivariable logistic regression, age was independently associated with the presence of comorbidity (OR=1.10, 95% CI:1.04–1.17; p=0.001), while arthritis demonstrated an inverse association (OR=0.15, 95% CI:0.03–0.80;p=0.024). 

Conclusion: In adult IgA vasculitis, comorbidity burden primarily reflects age-related risk rather than distinct organ involvement patterns. The higher frequencies of arthritis and gastrointestinal involvement among patients without comorbidities suggest that comorbidity status may subtly modify the clinical presentation. These findings indicate that comorbidity indices may offer complementary value in clinical evaluation by providing additional phenotypic and prognostic context.