Assessment of the impact of a CD4+ T-cell testing laboratory improvement program

To evaluate the effectiveness of the Centers for Disease Control and Prevention's CD4+ T-cell laboratory testing improvement program and the influence of other laboratory improvement programs on CD4+ T-cell testing practices.

Surveys asking for practice changes and factors that influenced the changes, a survey of clinicians' perceptions of laboratory quality in CD4 testing, and analysis of data from the Model Performance Evaluation Program.

Centers for Disease Control and Prevention interventions included a series of 3-day workshops on flow cytometry, CD4+ T-cell testing guidelines published in the Morbidity and Mortality Weekly Report, the Clinical Laboratory Improvement Amendments of 1988, and the Model Performance Evaluation Program.

All known laboratories in the United States that perform clinical CD4+ T-cell testing, workshop participants, and a sample of clinicians that treat patients infected with the human immunodeficiency virus.

Changes in practices, factors most influential in effecting change, and performance on samples mailed to laboratories by the Model Performance Evaluation Program; knowledge before and after presentation of material in workshops; and practicing clinicians' observations of any effects of changes in laboratory practices.

Many existing laboratories changed practices as a result of both governmental and nongovernmental CD4+ T-cell testing improvement programs. Sources of influence varied with each testing practice. Perceptions that test results were more reproducible seemed to offset presumed increases in the time and cost of testing. Clinicians who had ordered CD4+ T-cell testing for more than 10 years noted some improvements in results reported.

As new complex testing methodologies are introduced into clinical and public health laboratories, the users seem to seek guidance in appropriate application of preanalytic, analytic, and postanalytic phases of the testing process. Testing improvement programs from a variety of sources were credited with changing practices and should continue to provide this guidance.