Table 6.
GRADE summary of findings on diagnostic tools for screening strongyloidiasis, January 1993–February 2017.
| Index Test—at 10% Prevalence * | Sensitivity (95% CI) |
Specificity (95% CI) |
Post-Test Probability of a Positive Result (95% CI) |
Post-Test Probability of a Negative Result (95% CI) |
Number of Studies/ Participants |
Certainty of Evidence (GRADE) | Reference Standard |
|---|---|---|---|---|---|---|---|
| Baermann method [51] | 0.72 (0.67–0.76) a | 1.00 (1.00–1.00) a | 100% (100–100) | 3% (4–3) | 9/2459 | Moderate b,c | Combination of diagnostic tests |
| Agar plate—10% prevalence [51] | 0.89 (0.86–0.92) a | 1.00 (1.00–1.00) a | 100% (100–100) | 1% (2–1) | 10/3563 | Moderate b,c | Combination of diagnostic tests |
| NIE LIPS [62] d | 0.85 (0.79–0.92) | 0.95 (0.93–0.98) | 65% (56–84) | 2% (2–1) | 1/399 | Low e,f,g | Stool microscopy or culture |
| IVD ELISA—commercial test [62] | 0.92 (0.87–0.97) | 0.97 (0.96–0.99) | 77% (71–92) | 1% (1–0) | 1/399 | Low e,f,h | Stool microscopy |
| IFAT [62] | 0.94 (0.90–0.98) | 0.87 (0.83–0.91) | 45% (37–55) | 1% (1–0) | 1/399 | Low e,f,h | Stool microscopy and culture |
| Bordier-ELISA—commercial kit [62] | 0.91 (0.86–0.96) | 0.94 (0.91–0.96) | 63% (52–77) | 1% (2–0) | 1/193 | Low e,f,h | Kato–Katz, Flotac, and Baermann method |
| SS-NIE-1 ELISA [63] | 0.95 (0.92–0.97) | 0.93 (0.90–0.96) | 60% (71–73%) | 1% (1–0) | 1/583 | Low f,g,i | Stool microscopy and culture |
Notes: Population: patients with strongyloidiasis or sera infected with St. stercoralis; Settings: low-/high-endemic areas; Target condition: strongyloidiasis (test prevalence 10%). Cost effectiveness: serological testing may be cost-effective relative to stool and eosinophil testing for both strongyloidiasis and schistosomiasis, because of superior test performance characteristics. Tests: ELISA: enzyme-linked immunosorbent assay; GRADE: Grading of Recommendations, Assessment, Development and Evaluation; IFAT: indirect fluorescent antibody technique; IVD: Invitro diagnostic test; LIPS: luciferase immunoprecipitation system; NIE: a 31-kDa recombinant antigen from St. stercoralis. * Post-test probability of test was calculated at 10% prevalence for all the tests.
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a Sensitivity and specificity values obtained from a multiple-field study.
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b Evidence was downgraded because of serious inconsistencies and heterogeneity.
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c Heterogeneity between studies; use of intermediate or surrogate outcomes rather than health outcomes.
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d Test result with a primary standard.
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e Absence of a reliable gold standard for diagnosis of S. stercoralis infection. The review did not describe the specific gold standard used in the included studies for each test.
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f Single study design.
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g Samples were classified according to a composite reference standard, a procedure suggested for evaluation of diagnostic tests when there is no gold standard.
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h Use of intermediate or surrogate outcomes rather than health outcomes.
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i The inter-assay coefficient of variation was determined to be 22% for the low-positive control serum and 10% for the medium-positive control serum.