Accuracy comparison between PAPNET diagnoses and conventional diagnoses in an Italian cervical cytology laboratory

In a population-based cervical screening laboratory with a controlled workload, a retrospective PAPNET review of 1,654 Pap smears was performed. The series included a random sample of smears originally and conventionally classified as negative (no. 1,309) and unsatisfactory (no. 43), and 299 consecutive smears originally classified as abnormal. The PAPNET diagnoses and the original diagnoses were compared for accuracy. For smears with discordant classification, a majority diagnosis as obtained on manual review was used as a gold standard. The PAPNET testing showed a greater proportion of negative smears classified as unsatisfactory (3.7% vs. 0.2%; ratio, 16.7; 95% CI 12.4-22.0); a reduced proportion of ASCUS/LGSIL cases correctly identified as positive (i.e., a reduced sensitivity for such lesions) (76.3% vs. 97.9%; ratio, 0.78; 95% CI 0.66-0.91); an equal proportion (96.2%) of AGUS/HGSIL cases correctly identified as positive (i.e., an equal sensitivity for such lesions); and an equal proportion of negative smears correctly identified as such (i.e., an equal specificity). In conclusion, the PAPNET testing did not improve the diagnostic performance of the manual screening.