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Table 1 Characteristics of the study population

From: Predictors of persistently positive Mycobacterium-tuberculosis-specific interferon-gamma responses in the serial testing of health care workers

Variables n %
Subjects, total 182 100
TB screening risk classification   
   Low risk 17 9.3
   Medium risk 165 90.7
Reason for serial testing   
   (Bi-)Annual routine screening 48 26.4
   Follow-up after recent contact investigation 134 73.6
Sex   
   Male 59 29.1
   Female 123 70.9
Age categorized   
   18 to 39 years 104 57.1
   40 to 49 years 50 27.5
   ≥ 50 years 28 15.4
Foreign country of birth* 40 22.0
Birth in high-burden country# 8 4.4
BCG vaccination   
   Yes 95 52.2
   No 75 41.2
   Unknown 12 6.6
Health care professions   
   Nursing 56 30.8
   Physician 28 15.4
   Other 98 53.8
Affiliation with ID/TB Care 43 23.6
Family history of TB 14 7.7
Own history of TB 2 1.1
Prior TST 129 70.9
TST results   
   Positive prior TST result 54 41.9
   Recent TST > 5 mm induration 52 28.6
   Recent TST ≥ 10 mm induration 44 24.2
QFT-GIT results at baseline   
   Positive 18 9.9
   Negative 162 89.0
   Indeterminate 2 1.1
QFT-GIT results at follow-up   
   Positive 15 8.2
   Negative 164 90.1
   Indeterminate 3 1.7
  1. *Mostly Turkey (n = 17) and Poland (n = 9). #TB high-burden countries (according to WHO): Belarus (n = 2), Bosnia and Herzegovina (n = 1), Kazakhstan (n = 2), Morocco (n = 2), Philippines (n = 1). BCG = Bacillus Calmette-Guérin; ID = Infectious Diseases. QFT-GIT = QuantiFERON®-TB Gold In-Tube. TB = tuberculosis; TST = tuberculin skin test.