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Performance of a Molecular Classifier for Indeterminate Thyroid Nodules at a Large Community Hospital
Author(s) -
Avadhani Vaidehi,
Musleh Sarah,
Gupta Ashita,
Wang Beverly,
Marti Jennifer
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.926.16
Subject(s) - medicine , thyroid nodules , indeterminate , malignancy , thyroid , nodule (geology) , cytopathology , retrospective cohort study , radiology , surgical pathology , population , pathology , cytology , mathematics , pure mathematics , paleontology , environmental health , biology
The Afirma Gene Expression Classifier (GEC) is used to assess the risk of malignancy of indeterminate thyroid nodules (ITNs). In the largest study to date, it was reported to have a NPV of 94‐95% and a PPV of 37‐38%. Data from other institutions is limited, and its clinical utility may vary by institution. Our objective was to analyze the performance of the GEC classifier at a community hospital with high volume thyroid cytopathology. We examined the performance of the GEC at a comprehensive health system. Retrospective analysis of 64 ITNs was performed. We have previously calculated the prevalence of malignancy in ITNs as 10‐19% at our institution. Surgical pathology was correlated with GEC findings for each matched nodule. The mean age of our patients was 57 y, and 75% were female. Median nodule size was 2.4 cm. The GEC benign call rate was 50%. Of GEC‐benign nodules,16% underwent surgery; all were benign on surgical pathology. At the time of analysis, 50% of GEC‐suspicious nodules had undergone surgery. One of 16 (6%) was found to be malignant (Hurthle cell carcinoma). Therefore, the PPV of a GEC‐suspicious result was 6.3% (95%CI 0.2‐30.2). The estimated NPV was 95‐98.The performance characteristics (benign call rate, PPV and NPV) of a diagnostic test with given sensitivity and specificity are dependent on the prevalence of disease in the population. We observed a much lower PPV at our institution, compared to the experience at other institutions. Depending on practice setting, the implications of a benign or suspicious GEC result may differ. Knowledge of the prevalence of malignancy in ITNs at a particular institution is critical to the reliable clinical interpretation of GEC results.