Olfactory dysfunction in systemic sclerosis: a cross-sectional study and scoping review

Objective Olfactory dysfunction has been reported in autoimmune diseases, but its relationship with disease-specific features remains incompletely defined. We aimed to determine its prevalence in systemic sclerosis (SSc), assess clinical correlations and contextualise findings through a scoping review across connective tissue diseases (CTDs). Methods We conducted a single-centre cross-sectional study (January–March 2020) including 56 patients fulfilling the 2013 American College of Rheumatology/European Alliance of Associations for Rheumatology criteria for SSc. Olfaction was assessed using the European Test of Olfactory Capabilities (ETOC). Sinonasal status was evaluated with the Lund-Kennedy (LK) score and Sino-Nasal Outcome Test-22. Disease severity and activity were assessed using modified Rodnan Skin Score, Medsger scale, revised European Scleroderma Trials and Research Group activity index and Scleroderma Health Assessment Questionnaire, and mood with Hospital Anxiety and Depression Scale. A scoping review of PubMed and Embase (through September 2025) identified studies on olfactory dysfunction in CTDs. Results Median ETOC score was 28 (25–30). Hyposmia was present in 41% and anosmia in 2%, both associated with older age and higher LK scores (p<0.05). Olfactory function negatively correlated with age (r=−0.37, p=0.005) and LK score (r=−0.39, p=0.003), but not with disease severity, duration, quality of life or mood. The review included 19 studies (primary Sjögren’s disease (pSD) n=12, systemic lupus erythematosus (SLE) n=5, SSc n=2). Hyposmia prevalence ranged from 15% to 59% and anosmia from 3% to 13%, with associations including age, disease activity, mucosal dryness (pSD), neuropsychiatric involvement (SLE) and depression or brain changes (SSc). Conclusion Olfactory dysfunction is common in SSc and CTDs and appears to be partly related to age and sinonasal inflammation rather than overall disease severity, highlighting an under-recognised clinical feature.