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Table 2 TB transmission control measures and tuberculin skin test (TST) conversion: study details (n = 10)

From: Effectiveness of control measures to prevent occupational tuberculosis infection in health care workers: a systematic review

First author, year.
Country, period of study.
Sample size. Type of health care worker; Location
(B = before, A = After intervention)a
Transmission control measures
(Guidelines referenced as basis for intervention)
Cycles of observation
(B = before, A = After intervention)a
PPD, dose. (1- step test unless otherwise indicated)
Definition of conversion (induration diameter)
(TU = tuberculin units)
High-income settings (all USA)
Blumberg 1995. [27]
USA, 1992–1994.
3579 (B) and 2975–5153 (A1-A4).
HCWs; hospital, Atlanta
Administrative: Expanded and stricter respiratory isolation regimen. TB transmission control nurse. Expanded staff TB education.
Environmental: Rooms with negative pressure for respiratory isolation.
Personal: Submicron respirators for HCWs in isolation rooms.
(CDC 1990, 1994)
5 cycles:
B: 6 months
A1: 6 months
A2: 6 months
A3: 6 months
A4: 6 months
Aplisol or Tubersol, 5 TU.
Conversion: >  10 mm following prior negative test.
Jarvis, 1995. [28]
USA, 1989–1992.
152 (B) and 173 (A). HCWs; 2 hospitals, Miami, New York.
22 (B) and 33 (A).
HCWs; third hospital, New York.
Administrative: Education of staff for earlier recognition, diagnosis and rapid isolation of TB patients. Restriction of patient movement. Expanded TB drug regimen.
Environmental: Increase in number of AFB isolation rooms. Negative pressure in these rooms. Negative pressure ventilated booths for aerosol generating procedures.
Personal: Respirators and submicron surgical masks.
(CDC 1994)
B: Up to 24 months
A: Not given
PPD not specified.
Conversion: > 10 mm (baseline unknown) or > 10 mm increase in induration (baseline known).
Maloney, 1995. [29]
USA, 1990–1992.
90 (B) and 78 (A). Staff on wards with TB patients; hospital, New York.
254 (B) and 228 (A).
Staff on all other wards.
Administrative: Improved test based AFB isolation on admission. Expanded treatment regimen. More efficient and quicker laboratory diagnosis. Drug sensitivity probe added.
Environmental: AFB rooms with negative pressure. Portable chambers for cough inducing procedures.
Personal: Change from non-moulded to moulded surgical masks.
(CDC 1990).
B: 18 months
A: 14 months
PPD not specified.
Conversion: > 10 mm with negative prior test.
Wenger, 1995. [30]
USA, 1990–1992.
25 (B) and 27 (A). HCWs in HIV ward; hospital, Miami. Administrative: Stricter respiratory isolation regimen. Sputum induction only in isolation rooms. Additional laboratory staff with faster results turnaround.
Environmental: Automatic door closers in isolation rooms. Negative pressure isolation rooms and HIV ward. Aerosolised pentamidine in TB isolation rooms.
Personal: Surgical submicron masks worn in isolation rooms. Dust-mist particulate respirators (late intervention).
(CDC 1990)
3 cycles:
B: 5 months
A1: 9 months
A2: 16 months
PPD not specified. 5 TU.
Conversion: > 10 mm and at least 6 mm increase over previous induration.
Bangsberg, 1997. [31] USA, 1992–1994. 126 (B1-B2) and 124–138 (A1-A3). Medical house staff; hospital, New York. Administrative: Isolation of high risk patients. Specialised TB service for patients with HIV or known HIV risk factors and suspicion of pneumonia.
Environmental: Negative pressure rooms. UVGI in emergency and patient care areas.
Personal: Instruction and fit-testing on respirators to be worn by staff in care of isolated patients.
(CDC 1993)
5 cycles:
B1:11–35 months
B2: 6 months
A1: 6 months
A2: 6 months
A3: 6 months
Aplisol or Tubersol, 5 TU.
Conversion: ≥6 mm increase to a value of at least 10 mm.
Louther, 1997. [32]
USA, 1991–1994.
898 (B) and 971 (A).
HCWs; hospital, New York.
Administrative: Early respiratory isolation of suspected TB cases.b
Environmental: Negative pressure rooms. UVGI.
Personal: Face shield masks. Particulate and dust-mist-fume respirators.
(CDC 1994)
Bc: 24 months
A: 24 months
Aplisol, 5 TU 1991–1992; Tubersol, 5 TU 1993–1994. (2-step tested employees excluded; tests by outside physicians allowed.)
Conversion: > 10 mm increase over baseline within 2 years.
bInterventions assumed to be same as described in Fella et al.[20] (See Table 1).
c“Before” period simultaneous with introduction of intervention.
Behrman, 1998. [33] USA, 1993–1996. Intervention:
50 (B) and 64 (A). Emergency Department employees; hospital, Philadelphia. Controls:
2514 (B) and 3000 (A). Other hospital employees.
Administrative: None.
Environmental: Respiratory isolation rooms meeting CDC standards. Improved ventilation with at least 25% fresh air in the Emergency Department. 100% non-recirculated air in Trauma area. Laminar flow away from registrars with droplet shields.
Personal: None.
(CDC 1990)
B: 12 months
A: 12 months
PPD not specified. 5 TU.
Conversion: > 10 mm following prior negative test (<  5 mm).
Blumberg, 1998. [34] USA, 1992–1997. 2144 (B) and 2123 (A). Rotating house staff (residents and fellows); hospital, Atlanta. Administrative: Expanded and stricter respiratory isolation regimen. TB transmission control nurse. Expanded staff. TB education.
Environmental: Rooms with negative pressure for respiratory isolation.
Personal: Submicron respirators for HCWs in isolation rooms.
(CDC 1994)
B: 6 months
A: 54 months
Aplisol or Tubersol, 5 TU.
Conversion: > 10 mm following prior negative test.
Lower and middle-income settings
Yanai, 2003. [35] Thailand, 1995–1999. 369 (B) and 164 (A1).
HCWs; hospital, Chaing Rai.
Administrative: Training of HCWs on TB transmission prevention. Faster case detection, TB diagnosis, treatment initiation and isolation. Infectious patients trained in cough and mask practice. One-stop outpatient TB service with faster throughput and referral out.
Environmental: TB isolation rooms with negative pressure attached to wards. Increased natural ventilation in high risk wards. Safety cabinets, air exhaust and ultraviolet air disinfection in laboratory.
Personal: N95 respirators for HCWs. Air purified respirators with high efficiency particulate filters for laboratory staff.
(CDC 1994)
3 cycles:
B: 24 months (1995 to 1997)
A1: 12 months
A2: 12 months
Tubersol, 5 TU. 2-step test.
Conversion: > 10 mm increase over negative prior test (<  10 mm).
da Costa, 2009. [15]
Brazil, 1998–2003.
406 (B) and 193 (A).
HCWs; hospital, Rio De Janeiro.
Administrative: Increased respiratory isolation, rapid diagnosis.
Environmental: None.
Personal: Worker education in use of respirators.
(Guidelines not specified)
B: 23 months
A: 16 months
PPD not specified. 2-step where possible.
Conversion: > 10 mm increase over previous TST in 2-step; or > 15 mm increase in 1-step.
  1. PPD purified protein derivative, AFB acid fast bacillus, CDC Centers for Disease Control and Prevention, UVGI ultraviolet germicidal irradiation, HCWs health care workers
  2. aB1, B2, A1, A2, etc. if more than two cycles
  3. bInterventions that are assumed to be same as described in Fella et al. 20 (See Table 1).
  4. cThe "before" period is simultaneous with the introduction of intervention