Clinical Evaluation and Validation of Laboratory Methods for the Diagnosis of Bordetella pertussis Infection: Culture, Polymerase Chain Reaction (PCR), and Anti-Pertussis Toxin IgG Serology (IgG-PT) Open Access

Lee, Adria (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/d504rk94w?locale=en
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Abstract

Introduction. The appropriate use of clinically accurate diagnostic tests is essential for the detection of pertussis, a relatively poorly controlled vaccine-preventable disease. The purpose of this study was to estimate the sensitivities and specificities of different methods of diagnosing pertussis including culture, polymerase chain reaction (PCR), serology, and the use of a clinical case definition. An additional study objective was to describe the utility of pertussis serological testing in routine clinical practice.

Methods. Clinical specimens were collected from patients with cough illness between 2007 and 2011 at seven sites across the US. Sensitivities and specificities of each diagnostic test were estimated using three alternative "gold standards"--pertussis culture, composite reference standard (CRS), and latent class analysis (LCA) results. The effect of delayed blood specimen collection on serological testing accuracy was also assessed.

Results. In the total sample with non-missing data on all diagnostic tests, PCR was the most sensitive (> 90%) diagnostic test; it was also 100% specific. The LCA and CRS approaches generated similar estimates of the sensitivity and specificity for each test. When the analysis was restricted to a sub-group of participants with optimally-timed specimen collection, LCA provided lower estimates of the sensitivity of each test, compared to using culture as the gold standard or CRS analysis. Of the participants with both acute and convalescent serology results, 94% had concordant results at both time points. However, only 12% of participants with positive acute serology and 20% of participants with positive convalescent serology were classified as pertussis cases by LCA.

Conclusions. Convalescent pertussis serology is useful as an additional confirmatory diagnostic test in the clinical setting. Additionally, estimates of sensitivity and specificity and the accuracy of the diagnostic result are affected by the timing of specimen collection.

Table of Contents

I. Introduction........................................................................................................ 1

II. Methods.............................................................................................................. 4

a. Study Enrollment.......................................................................................... 4

b. Specimen Collection..................................................................................... 4

c. Laboratory Testing........................................................................................ 5

d. Data Analysis............................................................................................... 6

III. Results................................................................................................................ 8

a. Description of the Study Population............................................................. 8

b. Clinical Symptoms........................................................................................ 8

c. Laboratory Diagnostic Test Results............................................................... 8

d. Latent Class Model Results........................................................................... 9

e. Sensitivity and Specificity Estimates........................................................... 10

IV. Discussion........................................................................................................ 12

V. References........................................................................................................ 14

VI. Tables and Figures............................................................................................ 16

a. Box 1.......................................................................................................... 16

b. Figure 1...................................................................................................... 16

c. Figure 2...................................................................................................... 17

d. Table 1....................................................................................................... 18

e. Table 2....................................................................................................... 19

f. Table 3....................................................................................................... 19

g. Table 4....................................................................................................... 20

h. Table 5....................................................................................................... 20

i. Table 6....................................................................................................... 21

VII. Appendices....................................................................................................... 22

a. Appendix 1................................................................................................. 22

b. Appendix 2................................................................................................. 25

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