Elderly patients with tuberculosis in a low-incidence country - Clinical characteristics, inflammation and outcome

Susceptibility to respiratory infections increases with age. Diagnosing and treating tuberculosis in the elderly comes with the challenges of fewer specific symptoms and possibly more side effects of treatment. Much is unknown when it comes to tuberculosis in the elderly, especially in relation to inflammation, which may impact mortality. We, therefore, investigated a clinical cohort of elderly tuberculosis patients.

Patients aged ≥65 years, admitted to our tuberculosis reference center between 2005 and 2021, were retrospectively included in our cohort. Sociodemographic data, clinical characteristics, laboratory results, including inflammatory markers at baseline (monocyte, neutrophil, lymphocyte count, and CRP levels), and treatment outcomes were collected. They were compared to the National Dutch TB Registry and analyzed using descriptive statistics. Survival analysis was performed using univariate Cox regression analysis and a log-rank test. Results were visualized in Kaplan-Meier curves.

104 elderly tuberculosis patients, mostly European, with a mean age of 75 years, were included. None were HIV-infected. Miliary tuberculosis cases were overrepresented (14 %) compared to the National Dutch TB Registry (5 % in elderly, 2 % adults). Fever occurred in 77 % (57/74), and the duration of fever decreased with age. Innate immune markers, including monocyte/lymphocyte-ratio, moderately correlated with CRP. Overall mortality was 15 %, and highest (33 %) in patients with CRP levels >100 mg/mL.

In elderly tuberculosis patients in a low-incidence setting, mortality rates are higher in comparison to younger patients. The overrepresentation of miliary tuberculosis may suggest waning immunity, with a subset of patients exhibiting strong inflammation associated with increased mortality.