|
Performance characteristics of PCR at different parasite densities relative to expert laboratory microscopy for active surveillance for Plasmodium falciparum and Plasmodium vivax.a |
||||||
| Trophozoites/μl (total positive) |
Sensitivity (95% CI) |
Specificity (95% CI) |
Positive Predictive Value (95% CI) |
Negative Predictive Value (95% CI) |
Accuracy |
J Index |
|
|
||||||
| P. falciparum |
||||||
| >5000/μl (14) |
100.0% (73.2–100.0) |
97.7% (97.4–98.0) |
6.7% (3.9–11.3) |
100.0% (99.9–100.0) |
98% |
0.98 |
| >1000/μl (36) |
97.2% (83.8–99.9) |
98.0% (97.7–98.3) |
16.8% (12.1–22.8) |
100.0% (99.9–100.0) |
98% |
0.95 |
| >500/μl (47) |
95.7% (84.3–99.3) |
98.1% (97.8–98.4) |
21.6% (16.4–28.0) |
100.0% (99.9–100.0) |
98% |
0.94 |
| >100/μl (151) |
58.3% (50.0–66.2) |
98.6% (98.3–98.8) |
42.3% (35.6–49.3) |
99.2% (99.0–99.4) |
98% |
0.57 |
| >1/μl (267) |
41.6% (35.7–47.8) |
98.8% (98.6–99.0) |
53.6% (46.6–60.5) |
98.1% (97.8–98.4) |
97% |
0.40 |
| P. vivax |
||||||
| >5000/μl (4) |
100.0% (39.6–100.0) |
95.5% (95.0–95.9) |
1.0% (0.3–2.8) |
100.0% (99.9–100.0) |
95% |
0.95 |
| >1000/μl (15) |
100.0% (74.7–100.0) |
95.6% (95.2–96.0) |
3.8% (2.2–6.1) |
100.0% (99.9–100.0) |
96% |
0.96 |
| >500/μl (20) |
100.0% (80.0–100.0) |
95.7% (95.2–96.1) |
5.1% (3.2–7.9) |
100.0% (99.9–100.0) |
96% |
0.96 |
| >100/μl (96) |
71.9% (61.6–80.3) |
96.2% (95.8–96.6) |
17.6% (14.1–21.9) |
99.7% (99.5–99.8) |
96% |
0.68 |
| >1/μl (387) |
35.9% (31.2–40.9) |
96.9% (96.5–97.3) |
35.8% (31.1–40.8) |
97.0% (96.5–97.3) |
94% |
0.33 |
|
a For this analysis we assume that microscopy is the gold standard (i.e., always correct). | ||||||
Coleman et al. Malaria Journal 2006 5:121 doi:10.1186/1475-2875-5-121 |
||||||