Incidence, risk factors and clinical characteristics of extra‐pulmonary tuberculosis patients: a ten‐year study in the North of Iran

OBJECTIVE: To determine the incidence of extra-pulmonary tuberculosis (EPTB) and examine the risk factors and the clinical features of the disease over a ten-year period. METHODS: Retrospective study of records of patients who were followed and registered in the TB registry programme in the health district of Gorgan, Iran from January 1, 2008, through December 31, 2017. RESULTS: Among 2280 TB records, 609 (26.71%) were EPTB. They were mostly female patients (53.7%) and residents in rural areas (56.5%) with a mean age of 40.55 years [±16]. The average age of female patients (37.55 years [±16.99]) was lower than of male patients (44.07 years [±20.59]). The median of the incidence rate was 7.5 per 100 000 inhabitants for EPTB; biopsy and pathology were the best methods for the detection of EPTB. The most frequent forms of EPTB were lymphatic TB (193/609 = 31.7%) and pleural TB (158/609 = 25.9%). In most cases (245/609 = 40.2%), one to three months elapsed between occurrence of symptoms and final confirmation of EPTB. The outcome of EPTB was weaker than of pulmonary TB (PTB). CONCLUSION: Our most important finding was the increasing incidence of EPTB, which shows the importance of attention to this disease. Lymph node and pleural tissue were the most commonly infected tissues. Skeletal TB presents a challenge in the diagnosis and treatment of EPTB.