Table 1

Characteristics of the tuberculosis (TB) contacts by interferon-gamma release assay (IGRA) result

CharacteristicsNegativePositiveP value
(n=1059, 57%)(n=813, 43%)
Female—no. (%)606 (57)509 (63)0.002
Age—median (IQR)30 (15–44)36 (18–50)0.004
Race/ethnicity—no. (%)*0.003
 Black/Pardo813 (77)671 (83)
 Others245 (23)142 (17)
Income—no. (%)†0.954
 More than a minimum wage409 (40)276 (35)
 Equal or less than a minimum wage388 (38)357 (45)
 Without income225 (22)155 (20)
BCG scar—no. (%)950 (90)721 (89)0.498
HIV infection—no. (%)32 (3)14 (2)0.097
Antiretroviral therapy—no. (%)26 (8)10 (7)0.465
Education—no. (%)‡0.137
 Literate943 (89)743 (91)
 Illiterate114 (11)70 (9)
Smoking—no. (%)§253 (24)246 (30)0.002
Secondary smoking—no. (%)¶319 (30)281 (35)0.04
Alcohol consumption—no. (%)**565 (53)442 (54)0.674
Alcohol consumption (years)—median (IQR)10 (3–18)14 (5–25)0.002
CAGE score of 2 and above—no. (%)††110 (30)67 (24)0.075
Illicit drug use—no. (%)102 (10)84 (10)0.640
Comorbidities—no. (%)‡‡242 (23)199 (245)0.411
 Diabetes58 (6)34 (4)0.235
 Hypertension120 (11)111 (14)0.137
  • Data represent no. (%). or median with IQR.

  • 29 (1.5%) individuals had an indeterminate result in the first or second IGRA.

  • *Race ethnicity was self-reported. Others ethnicities: white, Asian and Indian.

  • †Income: monthly money received in the household, categorised in wage on this study. One Brazilian minimum wage was US$266/month (The World Bank), the average value in the period (2015–2019).

  • ‡Education: categorised in: literate: defined as patients who reported ability to read and write. Illiterate: defined as patients who reported unable to read or write.

  • §Smoking: defined as patients who reported currently smoking or before being diagnosed with tuberculosis.

  • ¶Secondary smoking: patients who reported being exposed to cigarette smoke from other smokers (passive smoker).

  • **Alcohol consumption: defined as patients who reported consuming currently alcohol or before being diagnosed with tuberculosis.

  • ††Alcohol abuse was defined as a CAGE score ≥2 points as described in Methods. Continuous variables were compared using the Mann-Whitney U test and categorical variables were using the Fisher’s exact test (2×2) or Pearson’s χ2 test. Missing information was identified in three variables: race (1 (0.05%)), income (62 (3.3%)) and education (2 (0.1%)). These three variables were imputed based on baseline variables and outcome.

  • ‡‡Comorbidities: at least one comorbidity (diabetes, hypertension, cancer, chronic obstructive pulmonary/emphysema, kidney disease, heart disease, liver disease and depression).