Proficiency testing in reticulocyte counting.

The Laboratory Proficiency Testing Program tests and evaluates proficiency of clinical laboratories in Ontario, Canada. The programme began in 1974; testing of reticulocyte counts was added in 1982. From the beginning, the goal of the programme has been to ensure that the quality of practice in Ontario laboratories facilitates good quality patient care. Testing of indirect counting methods for reticulocytes is accomplished by the distribution of stained blood films. Performance is expressed in terms of accuracy and precision. Proficiency is assessed by comparing submitted results to an all-methods' mean and result reliability by observing the coefficient of variation (CV) of the cohort. The quality of the results vary neither with the manual counting system used nor the type of laboratory. The CV commonly ranges from 25 to 30%, and this lack of accuracy appears to be inherent in the technology of manual reticulocyte counting. We conclude that manual reticulocyte counting is technologically obsolete but may be of clinical value if used in a qualitative fashion. It should probably be replaced by an automated method.