The epidemiology and association rules of concurrent pulmonary tuberculosis and extrapulmonary tuberculosis (PTB-EPTB) in China: a large-scale multi- center observational study

Background Tuberculosis (TB) is a multi-systemic disease with a protean presentation and remains a major global health problem. Concurrent pulmonary tuberculosis (PTB) and extrapulmonary tuberculosis (EPTB) are common in clinical practice. However, the information about concurrent PTB-EPTB is scarce. This study aimed to study the epidemiology of concurrent PTB-EPTB by summarizing the diagnostic types of TB and determine the association rules by a large-scale multi-center observational study in China.Methods The study was performed at 21 hospitals from 15 provinces in China. All the consecutive inpatient with confirmed TB diagnosis during the years from Jan 2011 to Dec 2017 was included in the study. The association rules of concurrent PTB-EPTB were analyzed by Apriori algorithm. Results Of 438,979 TB inpatients evaluated, the most common were PTB (82.05%), followed by tuberculous pleurisy (23.62%), etc. Concurrent PTB-EPTB occurred in 129,422 cases (29.48%). Concurrent PTB and tuberculous pleurisy was the most common concurrent PTB-EPTB types. In the fully adjusted multivariable logistic models, the odds ratio of concurrent PTB-EPTB was different by gender and age group. In PTB with concurrent EPTB, the strongest association rule was PTB with concurrent bronchial tuberculosis (lift=1.09). In EPTB with concurrent PTB, the strongest association rule was pharyngeal /laryngeal tuberculosis with concurrent PTB (lift=1.11). The confidence and lift of concurrent PTB-EPTB varied with gender and age. Conclusions There were many types of concurrent PTB-EPTB. The confidence and lift of concurrent PTB-EPTB varied with gender and age. The clinicians should be alert to the presence of concurrent PTB-EPTB and take effective treatment regimen.