Table 3.

Sensitivities, specificities, and positive and negative predictive values for Cobas Amplicor MTB and smear compared with culture results from one to three sputum specimens collected within a week from each patienta

No. of specimens (sample size)Cobas Amplicor MTBSmear
Sensitivity (%)Specificity (%)Positive predictive value (%)Negative predictive value (%)Sensitivity (%)Specificity (%)Positive predictive value (%)Negative predictive value (%)
One specimen (n = 151)82 (60–95)98 (89–100)95 (74–100)92 (81–97)59 (36–79)98 (89–100)93 (66–100)84 (71–92)
Two specimens (n = 99)82 (60–95)98 (89–100)95 (74–100)92 (81–97)59 (36–79)98 (89–100)93 (66–100)84 (71–92)
Three specimens (n = 69)91 (71–99)98 (89–100)95 (76–100)96 (86–99)64 (41–83)98 (89–100)93 (68–100)85 (73–93)
  • a The 95% confidence intervals are in parentheses.