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Table 4 Sensitivity, specificity, PPV and NPV of LM for detecting Plasmodium falciparum against nested PCR as a reference method

From: Field evaluation of a PfHRP-2/pLDH rapid diagnostic test and light microscopy for diagnosis and screening of falciparum malaria during the peak seasonal transmission in an endemic area in Yemen

 

PCR + ve

PCR + ve

PCR−ve

PCR−ve

Sensitivity

Specificity

PPV

NPV

% Agreement*

LM + ve

LM−ve

LM−ve

LM + ve

% (95 % CI)

% (95 % CI)

% (95 % CI)

% (95 % CI)

(Kc)

Overall

47

78

82

2a

37.6 (29.6–46.3)

97.6 (91.7–99.7)

95.9 (86.3–98.9)

51.3 (43.2–59.2)

61.7 (0.307)

Age (years) (n = 209)

≥10

41

65

71

2

38.7 (30.0–48.2)

97.3 (90.5–99.7)

95.3 (84.5–98.7)

52.2 (43.5–60.8)

62.6 (0.329)

<10

6

13

11

0

31.6 (12.6–56.6)

100 (71.5–100)

100 (54.1–100)

45.8 (25.6–67.2)

56.7 (0.253)

Fever 48 h prior to study (n = 209)

Yes

40

3

2

2

93.0 (81.4–97.6)

50.0 (6.8–93.2)

95.2 (84.2–98.7)

40.0 (5.3–85.3)

89.4 (0.386)

No

7

75

80

0

8.5 (3.5–16.8)

100 (95.5–100)

100 (59.0–100)

51.6 (43.5–59.7)

53.7 (0.084)

History of anti-malarial drug intake 1 week prior to the survey (n = 208)

Yes

19

37

30

0

33.9 (22.9–47.0

100 (88.4–100)

100 (83.2–100)

44.8 (33.5–56.6)

57.0 (0.264)

No

28

40

52

2

41.2 (30.3–53.0)

96.3 (87.5–99)

93.3 (78.7–98.2)

56.5 (46.3–66.2)

75.6 (0.349)

  1. CI confidence interval, PCR polymerase chain reaction, LM light microscopy, 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 LM and PCR divided by the total number of cases
  2. * The agreement between LM and PCR was significant in all categories with p < 0.05
  3. aParasite densities of these two cases were 80 parasites and 400 parasites/µL