Volume 21, Number 1—January 2015
Dispatch
Use of Treponema pallidum PCR in Testing of Ulcers for Diagnosis of Primary Syphilis1
Table 2
Summary of the various indices of performance of DFM compared with Tp-PCR or an enhanced definition for diagnosis of primary syphilis*
Reference testing, n = 170 | Sensitivity (95% CI) | Specificity (95% CI) | Likelihood ratios (95% CI) |
κ coefficient | Post-test probability (95% CI) |
||
---|---|---|---|---|---|---|---|
Positive | Negative | If Tp-PCR is positive (PPV) | If Tp-PCR is negative (1 − NPV) | ||||
Tp-PCR | 69.8% (53.9%–82.8%) | 98.4% (94.4%–99.6%) | 44.30 (11.05–177.68) | 0.31 (0.20–0.48) | 0.74 (0.62–0.87) | 93.8% (79.2%–99.2%) | 9.4% (5.6%–15.4%) |
Enhanced definition | 66.7% (51.6%–79.6%) | 100.0% (96.9%–100.0%) | 163.33 (10.2–2615.37) | 0.33 (0.22–0.50) | 0.74 (0.62–0.86) | 100.0% (89.3%–100.0%) | 11.6% (7.3%–18.0%) |
*Tp-PCR, Treponema pallidum PCR; DFM, darkfield microscopy; PPV, positive predictive value; NVP, negative predictive value.
1Preliminary results from this study were presented at the 53rd Interscience Conference on Antimicrobial Agents and Chemotherapy, September 10–13, 2013, Denver, Colorado, USA.