Proficiency testing in cytology in New York. Analysis of a 14-year state program.

A review of the first 14 years of the New York State Proficiency Testing Program in cytology shows the value of external quality-control evaluation based upon an established standard of performance as a prerequisite for licensure by a regulatory agency. Performance by participating laboratories has improved over the 14-year period. Hospital and independent laboratories had a higher pass rate than did state-run laboratories. Laboratories that did not employ cytotechnologists and performed fewer than 1,000 tests annually tended to have the lowest pass rates and consequently to undergo the most training before retesting and licensing. Overall, the predominant type of error, regardless of specimen type, was false negatives (underreads). Cervicovaginal false-negative errors by cytotechnologists ranged from 2% to 8%; such errors by cytopathologists ranged from 2.1% to 6.9%. Deficiencies and weaknesses detected by proficiency testing were remedied through a combination of surveillance and education.