TABLE 2

Summary of risk factors associated with the prevalence of latent tuberculosis (TB) infection measured by the tuberculin skin test (TST) or interferon-γ release assay (IGRA)

Factors	Occupational			Factors	Non-occupational
Factors	Studies assessed n	Studies showing statistically significant (p<0.05) association n [refs]	Studies showing no statistically significant association n [refs]	Factors	Studies assessed n	Studies showing statistically significant (p<0.05) association n [refs]	Studies showing no statistically significant association n [refs]
Healthcare workers (measured by TST)^#
Years of work	16	8 [13, 21, 37, 46, 47, 58, 62, 97]	8 [8, 24, 48, 55, 64, 65, 81, 85]	Male sex	20	4 [21, 47, 54, 74]	16 [8, 13, 24, 25, 36, 37, 46, 48, 52, 62, 64, 65, 81, 85, 92, 97]
Work location	9	4 [46, 64, 81, 97]	5 [13, 21, 37, 74, 85]	Age	18	4 [37, 47, 74, 94]	14 [8, 24, 36, 47, 48, 52, 54, 62, 64, 65, 81, 85, 92, 97]
Job category	13	2 [64, 65]	11 [8, 13, 21, 24, 37, 46, 55, 62, 74, 85, 92]	BCG scar/vaccination	13	4 [37, 46, 48, 54]	9 [8, 24, 25, 47, 52, 62, 81, 85, 97]
Contact with a TB patient	7	2 [21, 25]	5 [8, 24, 55, 62, 65]	Education level	8	2 [65, 81]	6 [8, 46–48, 62, 97]
Type of facility	4	1 [97]	3 [13, 21, 47]	Household contact with TB	5	2 [47, 81]	3 [24, 37, 92]
Ever had co-workers with TB	2	1 [47]	1 [24]	Smoking status	9	2 [36, 48]	7 [24, 37, 46, 47, 65, 85, 97]
Cared for a TB patient in last year	1	1 [47]		Chronic disease	2	2 [64, 65]
Last professional contact with pulmonary TB patients	1	1 [58]		Immunosuppression	2	1 [24]	1 [81]
Had TB infection control or TB training	3	1 [47]	2 [81, 97]	Diabetes mellitus	1	1 [64]
Aware of TB infection control guidelines	1	1 [47]
Healthcare students (measured by TST)^¶
Time (years) spent in healthcare work after entry	2	1 [28]	1 [34]	Male sex	6	2 [54, 59]	4 [28, 30, 53, 92]
Contact with a TB patient	3	1 [59]	2 [28, 53]	BCG scar/vaccination	4	2 [53, 54]	2 [28, 34]
				Age	7	1 [34]	6 [28, 30, 53, 54, 59, 92]
				TB knowledge	2	1 [92]	1 [59]
				Course type	1	1 [59]
Healthcare workers (measured by IGRA)⁺
Years of work	16	8 [10, 22, 37, 47, 48, 62, 68, 96]	8 [8, 38, 52, 55, 56, 70, 76, 93]	Age	15	5 [47, 62, 68, 76, 93]	10 [10, 37, 38, 48, 52, 55, 56, 90, 92, 96]
Job category	13	5 [10, 68, 76, 93, 96]	8 [8, 37, 52, 55, 56, 62, 90, 92]	Male sex	14	4 [37, 48, 52, 76]	10 [10, 38, 47, 55, 56, 62, 68, 90, 92, 96]
Contact with a TB patient	4	2 [55, 68]	2 [8, 62]	Household contact with TB	5	3 [10, 76, 96]	2 [37, 92]
Type of facility	3	2 [22, 56]	1 [47]	BCG scar/vaccination	9	2 [37, 47]	7 [10, 48, 52, 55, 62, 68, 93]
Work location	5	1 [38]	4 [37, 76, 90, 96]	Education level	7	2 [48, 56]	5 [47, 62, 68, 76, 96]
Ever had co-workers with TB	1	1 [47]		Body mass index	4	2 [56, 90]	2 [68, 76]
Average daily time in patient last year	1	1 [47]		Granulysin concentration	1	1 [90]
				Diabetes mellitus	1	1 [10]
Healthcare workers (measured by IGRA)^§
				Age	2	1 [34]	1 [92]
				Khat consumption^ƒ	1	1 [34]

BCG: bacille Calmette–Guérin. Factors assessed in studies that were not found to be significantly significant: ^#: HIV status [13, 21, 92], alcohol consumption [36, 37, 97], income [46, 48, 97], TB knowledge score [92]; ^¶: smoking status [30, 59], alcohol consumption [30, 59], body mass index [30, 34], HIV status [59], education [28], income [28], religion [28], household contact with TB [92]; ⁺: cared for a TB patient in last year [47], had TB infection control training [47], mask use [56], smoking status [10, 37, 47, 48], income [48, 76], comorbidity [37, 76], alcohol consumption [37], hepatitis C virus [10], TB knowledge score [92]; ^§: number of days spent working on medical wards [99], religion [34], BCG scar/vaccination [34], body mass index [34], male sex [92], HIV [92], household contact with TB [92], TB knowledge score [92]; ^ƒ: khat (Catha edulis is plant grown commonly in the horn of Africa; the leaves of khat are chewed by people for its stimulant action).