Table 3.

Evaluation of C. trachomatis and N. gonorrhoeae detection with the LCx and COBAS Amplicor systems using infected patient status as the reference standarda

Organism and systemSexSampleSensitivityb% (95% CI)Specificityb% (95% CI)PPVb% (95% CI)NPVb% (95% CI)
C. trachomatis
 LCx systemWomenSwab58/6392.1 (81.7–97.0)437/44099.3 (97.8–99.8)58/6195.1 (85.4–98.7)437/44598.2 (97.2–99.6)
Urine56/6388.9 (77.8–95.0)436/44099.1 (97.5–99.7)56/6093.3 (83.3–97.8)436/44398.4 (96.6–99.3)
MenSwab45/5090.0 (77.4–96.3)446/44899.6 (98.2–99.9)45/4795.7 (84.3–99.3)446/45198.9 (97.3–99.6)
Urine47/5094.0 (82.5–98.4)441/44898.4 (96.7–99.3)47/5487.0 (74.5–94.2)441/44499.3 (97.9–99.8)
 COBAS AMPLICOR systemWomenSwab61/6396.8 (88.0–99.4)436/44099.1 (97.5–99.7)61/6593.8 (84.2–98.0)436/43899.5 (98.2–99.9)
Urine52/6382.5 (70.5–90.6)439/44099.8 (98.5–100.0)52/5398.1 (88.6–99.9)439/45097.6 (95.5–98.7)
MenSwab49/5098.0 (88.8–99.9)444/44899.1 (97.6–99.7)49/5392.5 (80.9–97.6)444/44599.8 (98.6–100.0)
Urine46/5092.0 (79.9–97.4)448/448100 (98.9–100.0)46/46100.0 (90.4–100.0)448/45299.1 (97.6–99.7)
N. gonorrhoeae
 LCx systemWomenSwab6/6100.0 (51.7–100.0)497/497100.0 (99.0–100.0)6/6100.0 (51.7–100.0)497/497100.0 (99.0–100.0)
Urine6/6100.0 (51.7–100.0)497/497100.0 (99.0–100.0)6/6100.0 (51.7–100.0)497/497100.0 (99.0–100.0)
MenSwab21/21100.0 (80.8–100.0)477/477100.0 (99.0–100.0)21/21100.0 (80.8–100.0)477/477100.0 (99.0–100.0)
Urine20/2195.2 (74.1–99.8)477/477100.0 (99.0–100.0)20/20100.0 (80.8–100.0)477/47899.8 (98.7–100.0)
 COBAS AMPLICOR systemWomenSwab6/6100.0 (51.7–100.0)484/49797.4 (95.5–98.5)6/1931.6c (13.6–56.5)484/484100.0 (99.0–100.0)
Urine4/666.7c (24.1–94.0)490/49798.6 (97.0–99.4)4/1136.4c (12.4–68.4)490/49299.6 (98.4–99.9)
MenSwab21/21100.0 (80.8–100.0)473/47799.2 (97.7–99.7)21/2584.0 (63.1–94.7)473/473100.0 (99.0–100.0)
Urine20/2195.2 (74.1–99.8)474/47799.4 (98.0–99.8)20/2387.0 (65.3–96.6)474/47599.8 (98.6–100.0)
  • a Abbreviations: CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value.

  • b Data represent number of specimens positive or negative for the indicator/total number of specimens positive or negative according to infected patient status.

  • c P < 0.05 .