Epidemiology of Extrapulmonary Tuberculosis in Brunei Darussalam

Objectives We reported the prevalence and associated factors of extrapulmonary tuberculosis (EPTB) in Brunei Darussalam, an intermediate tuberculosis (TB)-burden country with stagnating annual TB rates. Methods A retrospective cohort study was conducted where sociodemographic, clinical and treatment outcome data for all active and notifiable TB cases in Brunei were collected between January 2001 and December 2018. Annual proportions of EPTB (overall and specific type) were calculated. Multiple logistic regression was done to investigate factors associated with developing EPTB, when compared to pulmonary TB (PTB). Chi-square trend test was used to determine any trends during the 18-year study period. Results We identified 3,916 TB cases, among which 743 (19.0%) were EPTB cases. Lymphatic (44.8%) and pleural (19.4%) EPTB were most common. The main modes of diagnosis were tissue biopsy (73.6%) and radiologic assessment (18.3%). Treatment success and mortality rate were 79.7% and 7.0%, respectively. Associations with specific EPTB types varies with age-group and gender. Younger age-group (adjusted Odds Ratio [aOR] ≥1.94) and females (aOR: 2.45 [95%CI: 1.94, 3.11]) had higher adjusted odds of developing lymphatic EPTB, but had lower adjusted odds of developing pleural EPTB [younger age-group (aOR ≤0.54) and female (aOR: 0.41 [95%CI: 0.17, 0.90])]. When compared to foreign residents, locals had higher adjusted odds of developing skeletal (aOR: 4.44 [95% CI: 2.04, 11.69]), gastrointestinal (aOR: 3.91 [95% CI: 1.84, 9.66]) and other types of EPTB (aOR: 3.42 [95% CI: 1.53, 9.14]). No significant trend differences were observed for overall and specific EPTB types. Conclusion Despite being generally non-infectious and less recognised than PTB, understanding EPTB epidemiology is important as it also contributes to the overall TB burden in a country. Future studies could be done to analyse the association between EPTB and presence of co-morbidities. Strengths and limitations of this study ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study is funded by Universiti Brunei Darussalam University Research Grant (Ref: UBD/RSCH/URC/RG(b)/2019/011). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethical approval was given by the Medical and Health Research and Ethics Committee, Ministry of Health, Brunei Darussalam (Ref: MHREC/UBD/2019/2). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors