Risk Factors and Outcomes of Disseminated Nocardiosis Across Host Risk Groups.

Background: Nocardiosis primarily affects immunocompromised hosts and those with chronic pulmonary disease but can also occur in immunocompetent patients. Predictors of dissemination and its role in long-term mortality remain unclear. Methods: We conducted a retrospective cohort study of adults with nocardiosis diagnosed from January 1, 2010 to December 31, 2023. Patients were categorized into 3 groups: immunocompromised, immunocompetent with chronic lung disease, and immunocompetent without chronic lung disease. We evaluated risk factors associated with dissemination at the time of diagnosis and predictors of 1-year mortality. Multivariable logistic regression identified risk factors for dissemination. Cox regression assessed predictors of 1-year mortality. Results: Among 232 patients, 44 (19.0%) had disseminated infection and 36 (15.5%) died within 1-year. Dissemination was more common among patients who were immunocompromised (odds ratio ([OR] 6.26, 95% confidence interval [CI] 2.26-20.53) or immunocompetent without chronic lung disease (OR 5.09, 95% CI 1.75-17.15). Lymphopenia and infection with Conclusions: Immunocompromised patients and those without chronic lung disease are at increased risk for disseminated nocardiosis. While dissemination alone is not predictive of 1-year mortality overall, it is directly associated with mortality among immunocompetent patients with chronic lung disease. These findings highlight the need for tailored prognostic assessment and management in this subgroup.