Table 1.

Systematic studies of the links between TB and concurrent diseases.

TB comorbidity	Number of studies included	Number of countries included	Year	Result	Reference
COPD *	19	27	1955-2011	A positive association between a past history of TB and the presence of chronic airflow obstruction.	Allwood et al., 2013
Lung cancer	42	9	1966-2009	A significant association between TB with adenocarcinoma.	Liang et al., 2009
Sarcoidosis	13	7	1990-2015	The existence of an association between M. tuberculosis and sarcoidosis.	Fang et al., 2016
SLE *	6	4	2008	TB incidence was higher in the SLE group compared to the control.	Prabu and Agrawal, 2010
DM *	13	8	1965-2007	DM was associated with higher TB risk in spite of study design and population	Jeon and Murray, 2008
Obesity	6	4	2008	A log-linear inverse relationship between TB incidence and body mass index.	Lönnroth et al., 2010
Hypovitaminosis D	7	8	1980-2006	Low serum vitamin D levels were associated with higher risk of active TB	Nnoaham and Clarke, 2008

^*COPD, chronic obstructive pulmonary disease; SLE, systemic lupus erythematosus; DM, diabetes mellitus.