This research aimed to explore the frequency of atypical or non-classical complications in adult-onset Still’s disease (AOSD), excluding macrophage activation syndrome (MAS), and to identify the factors associated with their occurrence. A multicenter cross-sectional analysis was carried out on AOSD patients listed in the Spanish registry focused on Still’s disease.
In total, 107 individuals (67% female) participated in the study, and 64 of them (59.8%) presented with non-classical complications. These complications consisted of macrophage activation syndrome in 9.5%, unusual skin lesions in 38.8%, heart-related problems in 22.7% (including pericarditis, myocarditis, pulmonary arterial hypertension, and noninfectious endocarditis), pleuritis in 28.9%, short-term lung shadows in 4%, notable headaches in 14.1%, lower belly discomfort accompanied by peritonitis signs in 8.4%, and secondary amyloidosis in 0.9%. Multivariate logistic regression revealed that lymphadenopathy (OR 2.85, 95% CI 1.03–7.91, P = 0.044) and the systemic score (SSC) index (OR 1.86, 95% CI 1.29–2.69, P = 0.001) were independent predictors of the emergence of non-classical manifestations. On the other hand, the presence of classic exanthema correlated with a decreased likelihood of such complications (OR 0.32, 95% CI 0.11–0.95, P = 0.041). Apart from the standard symptoms and MAS, a large share of AOSD patients experience rare complications, several of which carry a risk of becoming life-threatening. Clinicians should account for these issues when assessing and monitoring patients. Prompt detection and appropriate treatment play a key role in substantially lowering illness burden and death rates.
