Table 3. Summary of findings table for the review of PCR techniques for the diagnosis of Strongyloides stercoralis infection.
| Interpretative criteria to define: Index vs. Reference Test |
Effect (95% CI) |
Number of studies |
Mean Prevalence (95% CI) |
What do these results mean? |
|---|---|---|---|---|
|
All PCRa vs. Serology or parasitological methodsb |
Sensitivity: 61.8% (42.0–78.4) Specificity: 95.3% (92.0–97.2) |
17 | 21.1% (13.8 to 28.4) |
Assuming (based on the mean prevalence) 21 out of 100 patients with SSI, eight would be missed by a single PCR test (38% of 21). Of the 79 patients without SSI, four (5%) would have a false positive result of the PCR test. |
|
Al PCR vs. parasitological methods only |
Sensitivity: 71.8% (52.2–85.5) Specificity: 93.5% (90.3–95.6) |
14 | 18.5% (13.4 to 23.6) |
Assuming 18 out of 100 patients with SSI, five would be missed by a single PCR test. Of the 82 patients without SSI, five would have a false positive result of the PCR test. |
|
Real-time PCR vs. Serology or parasitological methods |
Sensitivity: 56.5% (39.2–72.4) Specificity: 95.4% (91.7–97.5) |
14 | 20.5% (11.6 to 29.4) |
Assuming 20 out of 100 patients with SSI, nine would be missed by a single PCR test. Of the other 80, four will have a false positive result of the PCR test. |
|
Real-time PCR vs. parasitological methods only |
Sensitivity: 64.4% (46.2–77.7) Specificity: 93.9% (90.3–96.3) |
12 | 20.3% (9.9 to 30.8) |
Assuming 20 out of 100 patients with SSI, seven would be missed by a single PCR test. Of the other 80, five would have a false positive result of the PCR test. |
PCR, polymerase chain reaction; SSI, S. stercoralis infection. Estimates for sensitivity and specificity are here reported in %.
a Studies included conventional PCR, nested PCR, real-time PCR
b Either Baermann method, agar plate culture, Harada-Mori culture, or a combination of fecal methods