The epidemiology of concurrent extrapulmonary tuberculosis in inpatients with extrapulmonary tuberculosis lesions in China: a large-scale observational multi-center investigation

AIMS

A high proportion of all tuberculosis (TB) cases present with extrapulmonary tuberculosis (EPTB), including concurrent EPTB involving more than one extrapulmonary lesion site within the body. However, previous reports only characterised lesions of single-site EPTB cases. This study aimed to investigate epidemiological characteristics and association rules of concurrent EPTB cases in China.

METHODS

An observational multi-centre study was carried out in China from Jan 2011 to Dec 2017 that included a total of 208,214 patients with EPTB lesions. Multivariable logistic regression analysis was used to identify associations between gender and age with concurrent EPTB. Association rules were analysed for significance using the Apriori algorithm.

RESULTS

The most prevalent form of EPTB lesion was tuberculous pleurisy (49.8%), followed by bronchial tuberculosis (14.8%) and tuberculous meningitis (7.6%). The most predominant concurrent EPTB case type was tuberculous pleurisy concurrent with tuberculous peritonitis (1.80%). Altogether 22 association rules were identified that included 20 strong association rules, among which highest confidence rates were found for tuberculous myelitis concurrent with tuberculous meningitis and sacral TB concurrent with lumbar vertebral TB. Moreover, association rules of EPTB concurrent with other EPTB types were found to vary with gender and age. The confidence rate of tuberculous myelitis concurrent with tuberculous meningitis was higher in females (83.67%) than males and highest in patients of ages 25-34 years (87.50%).

CONCLUSIONS

Many types of concurrent EPTB were found. Thus, greater awareness of concurrent EPTB disease characteristics is needed to ensure timely clinical diagnosis and treatment of this disease.

Factors associated with differential T cell responses to antigens ESAT-6 and CFP-10 in pulmonary tuberculosis patients

The T-SPOT.TB assay detects cellular immune responses to 2 core Mycobacterium tuberculosis antigens, early secreted antigenic target of 6-kDa protein (ESAT-6) and culture filtrate protein-10 (CFP-10). T-SPOT.TB has been recently used for auxiliary diagnosis of active pulmonary tuberculosis (PTB). However, testing can produce inconsistent results due to differential PTB patient immune responses to these antigens, prompting us to identify factors underlying inconsistent results.Data were retrospectively analyzed from 1225 confirmed PTB patients who underwent T-SPOT.TB testing at 5 specialized tuberculosis hospitals in China between December 2012 and November 2015. Numbers of spot-forming cells (SFCs) reflecting T cell responses to ESAT-6 and CFP-10 antigens were recorded then analyzed via multivariable logistic regression to reveal factors underlying discordant T cell responses to these antigens.The agreement rate of 84.98% (82.85%-86.94%) between PTB patient ESAT-6 and CFP-10 responses demonstrated high concordance. Additionally, positivity rates were higher for ESAT-6 than for CFP-10 (84.8% vs 80.7%, P < .001), with ESAT-6 and CFP-10 microwell SFC numbers for each single positive group not differing significantly (P > .99), while spot numbers of the single positive group were lower than numbers for the double positive group (P < .001). Elderly patients (aged ≥66 years) and patients receiving retreatment were most likely to have discordance results.ESAT-6 promoted significantly more positive T-SPOT.TB results than did CFP-10 in PTB patients. Advanced age and retreatment status were correlated with discordant ESAT-6 and CFP-10 results. Assessment of factors underlying discordance may lead to improved PTB diagnosis using T-SPOT.TB.

The epidemiology of extrapulmonary tuberculosis in China: A large-scale multi-center observational study

Tuberculosis (TB) remains a serious global public health problem in the present. TB also affects other sites (extrapulmonary tuberculosis, EPTB), and accounts for a significant proportion of tuberculosis cases worldwide. In order to comprehensively understand epidemiology of EBTB in China, and improve early diagnosis and treatment, we conducted a large-scale multi-center observational study to assess the demographic data and the prevalence of common EPTB inpatients, and further evaluate the prevalence of EPTB concurrent with Pulmonary tuberculosis (PTB) and the associations between multiple EPTB types and gender-age group in China. All consecutive age≥15yr inpatients with a confirmed diagnosis of EPTB during the period from January 2011 to December 2017 were included in the study. The descriptive statistical analysis included median and quartile measurements for continuous variables, and frequencies and proportions with 95% confidence intervals (CIs) for categorical variables. Multinomial logistic regression analysis was used to compare the association of multiple EPTB types between age group and gender. The results showed that the proportion of 15–24 years and 25–34 years in EPTB inpatients were the most and the ratio of male: female was 1.51. Approximately 70% of EPTB inpatients were concurrent with PTB or other types of EPTB. The most common of EPTB was tuberculous pleurisy (50.15%), followed by bronchial tuberculosis (14.96%), tuberculous lymphadenitis of the neck (7.24%), tuberculous meningitis (7.23%), etc. It was found that many EPTB inpatients concurrent with PTB. The highest prevalence of EPTB concurrent with PTB was pharyngeal/laryngeal tuberculosis (91.31%), followed by bronchial tuberculosis (89.52%), tuberculosis of hilar lymph nodes (79.52%), tuberculosis of mediastinal lymph nodes (79.13%), intestinal tuberculosis (72.04%), tuberculous pleurisy (65.31%) and tuberculous meningitis (62.64%), etc. The results from EPTB concurrent with PTB suggested that females EPTB inpatients were less likely to be at higher risk of concurrent PTB (aOR = 0.819, 95%CI:0.803–0.835) after adjusted by age. As age increasing, the trend risk of concurrent PTB decreased (aOR = 0.994, 95%CI: 0.989–0.999) after adjusted by gender. Our study demonstrated that the common EPTB were tuberculous pleurisy, bronchial tuberculosis, tuberculous lymphadenitis of the neck, tuberculous meningitis, etc. A majority of patients with pharyngeal/laryngeal tuberculosis, bronchial tuberculosis, tuberculosis of hilar/mediastinal lymph nodes, intestinal tuberculosis, tuberculous pleurisy, tuberculous meningitis, etc. were concurrent with PTB. Female EPTB inpatients were less likely to be at higher risk of concurrent PTB, and as age increasing, the trend risk of concurrent PTB decreased. The clinicians should be alert to the presence of concurrent tuberculosis in EPTB, and all suspected cases of EPTB should be assessed for concomitant PTB to determine whether the case is infectious and to help for early diagnosis and treatment.