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

## TL;DR

The study examines how nocardiosis spreads in different patient groups and finds that dissemination increases mortality risk in some but not all groups.

## Contribution

The study identifies distinct risk groups for dissemination and mortality in nocardiosis patients, emphasizing subgroup-specific outcomes.

## Key findings

- Dissemination is more common in immunocompromised and immunocompetent patients without chronic lung disease.
- Dissemination is significantly associated with 1-year mortality in immunocompetent patients with chronic lung disease.
- Lymphopenia and infection with Nocardia farcinica are independently linked to dissemination.

## Abstract

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.

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.

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 Nocardia farcinica were also independently associated with dissemination. Dissemination was not associated with mortality overall (hazard ratio [HR] 1.58, P = .222), though interaction analysis revealed that dissemination was significantly associated with 1-year mortality only in immunocompetent patients with chronic lung disease (HR 9.43, 95% CI 1.73–51.52).

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.

Nocardiosis affects immunocompromised hosts, individuals with chronic pulmonary disease, and apparently immunocompetent patients. Risk of dissemination and its impact on mortality varies between risk groups categories. Our findings highlight the need for tailored prognostic assessment and management by subgroup.