Table 3.
Sensitivity, specificity, PPV and NPV of PfHRP-2/pLDH RDT for detecting Plasmodium falciparum against nested PCR as a reference method
| PCR + ve | PCR + ve | PCR−ve | PCR−ve | Sensitivity | Specificity | PPV | NPV | % Agreement* | |
|---|---|---|---|---|---|---|---|---|---|
| RDT + ve | RDT−ve | RDT−ve | RDT + ve | % (95 % CI) | % (95 % CI) | % (95 % CI) | % (95 % CI) | (Kc) | |
| Overall | 119 | 5 | 47 | 37 | 96.0 (90.9–98.3) | 56.0 (44.7–66.8) | 76.3 (69.0–82.3) | 90.4 (78.8–96.8) | 79.8 (0.553) |
| Age (years) (n = 208) | |||||||||
| ≥10 | 100 | 5 | 41 | 32 | 95.2 (89.3–97.9) | 56.2 (44.1–67.8) | 75.8 (67.8–82.3) | 89.1 (76.4–96.4) | 79.2 (0.545) |
| <10 | 19 | 0 | 6 | 5 | 100 (82.4–100) | 54.6 (23.4–83.3) | 79.2 (57.9–92.9) | 100 (54.1–100) | 83.3 (0.603) |
| Fever 48 h prior to survey (n = 208) | |||||||||
| Yes | 42 | 0 | 2 | 2a | 100 (92.3–100) | 50.0 (6.8–93.2) | 95.5 (84.9–98.7) | 100 (15.8–100) | 95.3 (0.646) |
| No | 77 | 5 | 45 | 35 | 93.9 (86.3–98.0) | 56.3 (44.7–67.3) | 68.8 (59.3–77.2) | 90.0 (78.2–96.7) | 75.3 (0.504) |
| History of anti-malarial drug intake 1 week prior to the survey (n = 207) | |||||||||
| Yes | 52 | 2 | 9 | 21 | 96.3 (87.5–99.0) | 30 (14.7–49.4) | 71.2 (60.0–80.3) | 81.8 (48.2–97.7) | 72.6 (0.306) |
| No | 66 | 3 | 38 | 16 | 95.7 (88.0–98.5) | 70.4 (57.2–80.9) | 80.5 (70.6–87.6) | 92.7 (80.6–97.5) | 84.6 (0.678) |
CI confidence interval, PfHRP-2 P. falciparum histidine-rich protein-2, pLDH Plasmodium lactate dehydrogenase, RDT rapid diagnostic test, PCR polymerase chain reaction, PPV positive predictive value, NPV negative predictive value, Kc Cohen’s kappa coefficient; % agreement was calculated by summation of the number of positives and negatives by both RDT and PCR divided by the total number of cases
* The agreement between RDT and PCR was significant for all categories with p < 0.001
aParasite densities of these two cases were 80 parasites and 400 parasites/µL