Fool's Gold: Why Imperfect Reference Tests Are Undermining the Evaluation of Novel Diagnostics: A Reevaluation of 5 Diagnostic Tests for Leptospirosis

Limmathurotsakul, Direk; Turner, Elizabeth L.; Wuthiekanun, Vanaporn; Thaipadungpanit, Janjira; Suputtamongkol, Yupin; Chierakul, Wirongrong; Smythe, Lee D.; Day, Nicholas P. J.; Cooper, Ben; Peacock, Sharon J.

doi:10.1093/cid/cis403

Cited by 177 publications

(192 citation statements)

References 29 publications

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“…There is a possibility of some false positives in the in-house test, which we are unable to comment on due to the lack of a gold standard for proper evaluation of specificity. 10 Further, we did not have paired samples for some patients to exclude potential false positives in some of these ELISA-positive patients. Previous studies have consistently shown ELISA to be more sensitive than MAT in the acute phase.…”

Section: Discussionmentioning

confidence: 99%

“…9 A large prospective study from Thailand convincingly showed that the MAT is not a perfect test. 10 Other work has shown that the use of a quantitative polymerase chain reaction (qPCR) increases the diagnostic sensitivity even in comparison to the MAT using paired serum sample. 11 This shows that a combination of MAT plus molecular testing ought to be considered as a gold standard.…”

Section: Introductionmentioning

confidence: 99%

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Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

Agampodi

Dahanayaka

Nöckler

et al. 2016

The American Society of Tropical Medicine and Hygiene

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Abstract. A gap in the leptospirosis field remains the lack of well-characterized sample collections that allow for comparison of new methods to standard ones. In the context of a flood-related outbreak of leptospirosis evaluated in Anuradhapura, Sri Lanka, a specimen bank was obtained with detailed metadata accompanied by gold standard diagnostic test results. Blood samples collected on admission and 14 days later from suspected cases of leptospirosis were tested using microscopic agglutination test (MAT) (17 serovars), an in-house enzyme-linked immunosorbent assay (ELISA) using a locally obtained strain of Leptospira kirschneri as sonicated antigen, a commercially available ELISA based on sonicated Leptospira biflexa, and a quantitative polymerase chain reaction (qPCR) assay targeting the pathogenic Leptospira-specific 16S rRNA gene. Of 62 patients presenting within the first 2 days of illness, 31 had confirmed leptospirosis based either on paired-sample MAT or qPCR. During the acute phase, qPCR was most sensitive, detecting 74% of definitively diagnosed cases; immunoglobulin G (IgG) ELISA (in-house), IgG ELISA (commercial), and MAT had sensitivities of 35.5%, 12.0%, and 22.6%, respectively, in detecting definitively diagnosed cases using acute phase serum. Of 40 patients with paired sera, 10 were qPCR positive. Of these, five samples were negative by paired-sample MAT. Of the 11 MAT-positive samples, only five were detected using qPCR confirming that both tests are needed for maximal sensitivity. Regional leptospiral serovar-specific IgG ELISA was superior to MAT. Knowing the regionally dominant serovars improves serological sensitivity in the analysis of acute specimens by ELISA, but qPCR was most sensitive in this patient population.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

Agampodi

Dahanayaka

Nöckler

et al. 2016

The American Society of Tropical Medicine and Hygiene

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“…The failure of MAT to identify all clinically proven cases of leptospiral uveitis, as seen in this study and in an earlier study (Priya et al, 2003), both showing a low specificity of 58 %, indicates strongly that MAT cannot be used as the gold standard for diagnosis of leptospiral uveitis, as is currently being done (15) for systemic leptospirosis. There are also reports of the low sensitivity of MAT in diagnosing the latter, even at the optimal stage of systemic leptospiral infection (Limmathurotsakul et al, 2012;Goris et al, 2012). Agglutination of live organisms in MAT is due predominantly to the presence of antibodies against the highly antigenic lipopolysaccharide determinants that are specific to each serovar.…”

Section: Discussionmentioning

confidence: 99%

Serological diagnosis of leptospiral uveitis by HbpA IgG ELISA

Sivakolundu

Sivakumar²,

Chidambaranathan³

et al. 2012

Journal of Medical Microbiology

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Leptospirosis is a zoonotic disease that is highly prevalent in tropical countries; uveitis is one of the manifestations of leptospirosis. The leptospiral aetiology of uveitis is difficult to predict because of overlapping clinical symptoms with uveitis due to other causes. The objective of this study was to evaluate the leptospiral haemin-binding protein HbpA as a diagnostic antigen for the serodiagnosis of leptospiral uveitis. Serum samples from patients, clinically diagnosed with leptospiral uveitis, were tested by ELISA for anti-HbpA antibodies and compared against the 'gold standard' microscopic agglutination test (MAT). Non-leptospiral uveitis and normal healthy individuals were used as controls. A total of 60 serum samples from patients suffering from leptospiral uveitis were studied, obtained from Aravind Eye Hospital, Madurai. Anti-HbpA IgG antibodies were detected in 92 % of patients clinically diagnosed with leptospiral uveitis, indicating that it is more sensitive than MAT, which had a seropositivity of only 50 %, and better than the commercially available Pan Bio IgM ELISA (81 %). The mean anti-HbpA antibody titre was significantly higher in leptospiral uveitis patients compared with controls (P,0.05). The antigen showed negligible cross-reactivity with non-leptospiral uveitis samples and cataract controls. We conclude that HbpA IgG ELISA identified cases of uveitis with leptospirosis aetiology and proved to be useful in differentiating them from other forms of uveitis.

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“…In this study the MAT test was assumed to be perfect, as this test is usually regarded to be the gold standard test. However, other studies found that the sensitivity of the MAT test is far below 100% [22][23][24][25]. Cumberland et al [22] found the sensitivity to be 30% for first acute-phase specimens, 63% for second acute-phase specimens, and 76% for convalescent specimens.…”

Section: Examplementioning

confidence: 99%

“…At the same time specificity was 99%, 98%, and 97%, respectively. Limmathurotsakul et al [25] estimated the sensitivity of MAT by a Bayesian analysis and found it to be 49·8%. These findings indicate the need for an adjustment of the PR estimates.…”

Section: Examplementioning

confidence: 99%

Exact inference for the risk ratio with an imperfect diagnostic test

Reiczigel

Singer²,

Láng

2016

Epidemiol. Infect.

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SUMMARYThe risk ratio quantifies the risk of disease in a study population relative to a reference population. Standard methods of estimation and testing assume a perfect diagnostic test having sensitivity and specificity of 100%. However, this assumption typically does not hold, and this may invalidate naive estimation and testing for the risk ratio. We propose procedures that control for sensitivity and specificity of the diagnostic test, given the risks are measured by proportions, as it is in crosssectional studies or studies with fixed follow-up times. These procedures provide an exact unconditional test and confidence interval for the true risk ratio. The methods also cover the case when sensitivity and specificity differ in the two groups (differential misclassification). The resulting test and confidence interval may be useful in epidemiological studies as well as in clinical and vaccine trials. We illustrate the method with real-life examples which demonstrate that ignoring sensitivity and specificity of the diagnostic test may lead to considerable bias in the estimated risk ratio.

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Fool's Gold: Why Imperfect Reference Tests Are Undermining the Evaluation of Novel Diagnostics: A Reevaluation of 5 Diagnostic Tests for Leptospirosis

Abstract: We hypothesized that the gold standard for diagnosing leptospirosis is imperfect. We used Bayesian latent class models and random-effects meta-analysis to test this hypothesis and to determine the true accuracy of a range of alternative tests for leptospirosis diagnosis.

Cited by 177 publications

References 29 publications

Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

Redefining Gold Standard Testing for Diagnosing Leptospirosis: Further Evidence from a Well-Characterized, Flood-Related Outbreak in Sri Lanka

Serological diagnosis of leptospiral uveitis by HbpA IgG ELISA

Exact inference for the risk ratio with an imperfect diagnostic test

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