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Table 1 Results from routine testing of patients with risk factors for M. tuberculosis infection using a PPD-based whole blood interferon-γ release assay (IGRA), stratified by testing site. San Francisco, November 2003 – February 2005

From: Feasibility, acceptability, and cost of tuberculosis testing by whole-blood interferon-gamma assay

  Homeless Clinics (n = 2) TB Clinic Immigrant & Refugee (n = 2) Methadone Clinic Total
IGRA Result n (%) n (%) n (%) n (%) N (%)
Positive 411 (16) 213 (33) 164 (34) 31 (17) 819 (21)
Negative 2148 (82) 419 (64) 303 (63) 140 (76) 3010 (77)
Indeterminate 41 (2) 21 (3) 14 (3) 13 (7) 89 (2)
Total tested 2600 642 481 184 3918