# Trends, challenges, and outcomes of extrapulmonary tuberculosis: a ten-year study in Cologne (2012–2022)

## TL;DR

This study examines extrapulmonary tuberculosis in Cologne over ten years, finding it remains stable and harder to treat than pulmonary TB, especially among migrants.

## Contribution

The study provides a detailed 10-year analysis of EPTB epidemiology, diagnostics, and treatment outcomes in a major German city.

## Key findings

- EPTB accounted for 33% of all TB cases, with lymph nodes as the most common site.
- EPTB was more prevalent among individuals from high TB incidence countries.
- Treatment success rates for EPTB were below the WHO target of 90%.

## Abstract

Extrapulmonary tuberculosis (EPTB) presents significant challenges in diagnosis and treatment and generally receives less attention than pulmonary tuberculosis (PTB).

We conducted a retrospective analysis of tuberculosis (TB) patients reported to the public health department of Cologne from 2012 to 2022 focussing on EPTB, its epidemiology, diagnostic methods, and treatment protocols, within a major German city. A subgroup analysis of EPTB patients (2012–2019, n = 254) examined diagnostic accuracy, treatment regimens, and adherence.

Of 1,003 notified TB diagnoses, 33% (329/1,003) were identified as EPTB, with lymph nodes being the most frequently affected site. Mycobacterium tuberculosis was the predominant pathogen. EPTB was significantly more prevalent among individuals from countries with high TB incidence rates (41%, p < 0.001) compared to those from regions with moderate or low incidence. Direct pathogen detection was most frequently achieved by tissue culture (163/199, 82%), followed by polymerase chain reaction (PCR; 161/205, 79%). The standard combination therapy was used in > 95% of patients, aligning to national guidelines.

In contrast to declining PTB incidence, EPTB remained stable. Overall documented treatment success rate (79%) fell short of the WHO target (≥90%), underscoring the need for improved case management and reporting strategies.

Enhanced awareness, specialised care, and targeted interventions for migrant populations are critical to achieving global TB control objectives.