Extrapulmonary tuberculosis in Cologne 2012-2022: a retrospective analysis validating national patterns

Introduction: Tuberculosis (TB) remains a widespread and life-threatening global infectious disease. Extrapulmonary tuberculosis poses unique challenges in both diagnosis and treatment. This study's goal was to investigate cases of extrapulmonary TB, with a particular focus on epidemiology, diagnostic methods, and treatment practices, within a major German city over a ten-year period. The study aimed to ascertain the incidence rate and identify patient groups at higher risk, comparing them to cases of pulmonary TB.

Methods: We performed a retrospective analysis of case data reported to the public health department of the city of Cologne for both extrapulmonary and pulmonary TB cases during the period from 2012 to 2022. For extrapulmonary TB cases, in addition to analyzing the reported data, we conducted a review of patient files to gather information about prior medical conditions, diagnostic procedures, and treatments.

Results: We analyzed a total of 1003 reported TB cases from 2012 to 2022. Among these, 32% (254/803) were identified as extrapulmonary TB. Lymph nodes were most frequently affected followed by pleural manifestation. Mycobacterium tuberculosis was the predominant pathogen type, accounting for 223 (88%) cases. The majority of the detected species were pan-susceptible (166/254, 65%), with 189 cases having susceptibility data available.

The average length of hospital stay for patients with extrapulmonary TB was 14.5 days, and the mean total therapy duration was 257 days. Approximately 40% (99/252) of patients with extrapulmonary TB had some form of immunosuppression.

There was a significant difference in gender distribution, with pulmonary TB being more common in male patients and extrapulmonary TB occurring more frequently in women.

The majority of infected individuals originated from Europe (622/1003, 62%) or countries with a low TB incidence (<10/100,000) (397/1003, 40%). Pulmonary TB was more prevalent in individuals from these regions (302/647, 45%). In contrast, extrapulmonary TB was significantly more common in people from high-incidence countries (>100/100,000) (133/315, 42%, p<0.0001). Approximately 16% of all TB cases were asylum seekers.

The overall mean TB incidence rate was 8.1/100,000, with the highest rates observed in 2016 and 2017 (10.4 and 9.5, respectively). Pulmonary TB incidence decreased, but extrapulmonary TB remained relatively stable. Particularly among asylum seekers, there was an increasing trend in extrapulmonary TB incidence over the years.

Conclusion: Extrapulmonary TB exhibits distinct epidemiological patterns compared to pulmonary TB. Migration appears to be a significant factor in this regard. Therefore, in regions with a high incidence of TB, especially when pulmonary TB has been ruled out, healthcare providers should maintain a high index of suspicion for TB when treating patients with relevant symptoms. In a broader context, our study aligns with the nationwide trend related to TB.

Publication History

Article published online:
10 April 2024