Clinical characteristics of peripheral blood eosinophilia in nontuberculous mycobacterial disease: a multicenter comparative retrospective study.

BACKGROUND AND OBJECTIVES: Peripheral blood eosinophilia occurs in some patients with nontuberculous mycobacterial (NTM) disease, but its clinical significance remains unclear. METHODS: The clinical data of 199 HIV-negative patients with NTM disease from four hospitals were retrospectively analyzed. Clinical characteristics and treatment outcomes were compared between patients with and without eosinophilia. Multivariable logistic regression and sensitivity analyses were used to evaluate the independent association between peripheral blood eosinophilia and disseminated NTM disease. RESULTS: Of the 199 included patients, 60 had eosinophilia and 139 did not. Compared with the non-eosinophilia group, the eosinophilia group had a significantly higher proportion of disseminated disease (70.0% vs. 19.4%) and more frequently presented with systemic symptoms. Concurrent fungal infections and anti-interferon-γ autoantibody (AIGA) syndrome were more common in this group. Chest CT showed higher detection rates of solitary nodules/masses, fibrotic changes, pleural effusion, and hilar lymphadenopathy in the eosinophilia group. Baseline systemic inflammatory markers and immunoglobulin levels were also significantly elevated. After anti-infective treatment, peripheral blood eosinophil counts gradually decreased and normalized within 3 months, accompanied by the resolution of clinical symptoms and a decline in inflammatory markers. Multivariable logistic regression analysis revealed that peripheral blood eosinophilia was significantly and independently associated with disseminated NTM disease. CONCLUSION: NTM patients with elevated peripheral blood eosinophils are more prone to disseminated infection with augmented systemic inflammatory and immune responses, and frequently complicated with AIGA syndrome and fungal infections. Peripheral blood eosinophilia is significantly and independently associated with disseminated NTM disease in HIV-negative patients. Elevated eosinophil levels decrease after anti-NTM treatment, accompanied by marked improvements in clinical symptoms and inflammatory markers, suggesting a potential correlation between eosinophil levels and treatment response.