The olfactory function is impaired in patients with idiopathic inflammatory myopathies

The aim of our study was to analyze olfactory function in patients with idiopathic inflammatory myopathies (IIM). We performed a case-control study on 60 IIM patients (48 females and 12 males) and 60 healthy controls (HC) recruited by the best friend method, matched for age, sex and lifestyle. Olfactory function was analyzed by "Sniffin' sticks test" and expressed through a score (TDI), indicating normosmia (TDI > 30), hyposmia (TDI 15-30) and anosmia (TDI < 15). Mood was investigated by Beck depression inventory (BDI) test. Statistic was performed using SPSS package. Mean ± SD TDI was significantly reduced in patients versus HC (26.8 ± 5.2 vs. 31.4 ± 3.5, p < 0.001). Anosmia was detected in two patients (3.3 %) and no HC, hyposmia in 41 patients and 14 HC (68.3 vs. 23.3 %, p < 0.0001) and normosmia in 17 patients and 48 HC (28.3 vs. 76.6 %, p < 0.0001). In the multivariate analysis carried out in the pool population of patients and HC, low TDI score was associated with age ≥50 years (p < 0.0001), disease status (p < 0.0001) and high BDI (p = 0.007). When adjusting for BDI, disease status was still associated with low TDI (p = 0.037). In IIM, TDI was lower in subjects aged ≥50 years (p = 0.008) and in patients who were taking corticosteroids (p < 0.0001). In the multivariate analysis carried out in IIM patients, low TDI was associated with age ≥50 years (p = 0.001) and prednisone intake (p < 0.0001). The olfactory function is impaired in IIM patients. An underlying immune-mediated mechanism is conceivable, yet a possible interference due to age, steroid intake and depression should be considered.