title: Association of Malignancy Prevalence With Test Properties and Performance of the Gene Expression Classifier in Indeterminate Thyroid Nodules.
abstract: It is crucial for clinicians to know the malignancy prevalence within each indeterminate cytologic category to estimate the performance of the gene expression classifier (GEC).
  
  
  
  To examine the variability in the performance of the GEC.
  
  
  
  This retrospective cohort study of patients with Bethesda category III and IV thyroid nodules used single-institution data from January 1, 2013, through February 29, 2016. Expected negative predictive value (NPV) was calculated by adopting published sensitivity and specificity. Observed NPV was calculated based on the true-negative rate. Outcomes were compared with pooled data from 11 studies published January 1, 2010, to January 31, 2016.
  
  
  
  A total of 145 patients with 154 thyroid nodules were included in the study (mean [SD] age, 56.0 [16.2] years; 106 females [73.1%]). Malignancy prevalence was 45%. On the basis of this prevalence, the expected NPV is 85% and the observed NPV is 69%. If the prevalence is assumed to be 25%, the expected NPV would be 94%, whereas the observed NPV would be 85%. Pooled data analysis of 11 studies comprising 1303 participants revealed a malignancy prevalence of 31% (95% CI, 29%-34%) and a pooled NPV of 92% (95% CI, 87%-96%).
  
  
  
  In this study, variability in the performance of the GEC was not solely a function of malignancy prevalence and may have been attributable to intrinsic variability of the test sensitivity and specificity. The utility of the GEC in practice is elusive because of this variability. A better definition of the GEC's intrinsic properties is needed.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City.
authors.forename: Zaid
authors.initials: Z
authors.lastname: Al-Qurayshi
authors.affiliation: Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Deniwar
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Tina
authors.initials: T
authors.lastname: Thethi
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Tilak
authors.initials: T
authors.lastname: Mallik
authors.affiliation: Department of Biostatistics and Bioinformatics, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana.
authors.forename: Sudesh
authors.initials: S
authors.lastname: Srivastav
authors.affiliation: Division of Endocrine and Oncological Surgery, Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Fadi
authors.initials: F
authors.lastname: Murad
authors.affiliation: Division of Endocrine and Oncological Surgery, Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Parisha
authors.initials: P
authors.lastname: Bhatia
authors.affiliation: Department of Pathology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Moroz
authors.affiliation: Department of Pathology, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Sholl
authors.affiliation: Division of Endocrine and Oncological Surgery, Department of Surgery, Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Emad
authors.initials: E
authors.lastname: Kandil
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000453:epidemiology* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D015995:Prevalence; D012189:Retrospective Studies; D016606:Thyroid Nodule / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D013965:Thyroidectomy