Variability of reporting and lack of adherence to consensus guidelines in human T-lymphocyte immunophenotyping...

Percentages and absolute counts of CD4+ lymphocytes, as determined by T-lymphocyte immunophenotyping (TLI), are prognostic, as well as diagnostic, of the course of human immunodeficiency virus type 1 infections and are important indicators for initiating Pneumocystis carinii pneumonia prophylaxis and antiretroviral therapy. In December 1990, we requested that a nonrandom sample of 17 laboratories provide us with typical reports of their TLI results from an immunodeficient patient and from a patient whose TLI results were within the laboratory's normal reference ranges. We also searched published literature and documents proposed by professional organizations for recommendations regarding T-lymphocyte testing and reporting. This article compares guidelines for reporting TLI results, as proposed by the National Committee for Clinical Laboratory Standards in Document H42-P, with samples of reports obtained in our case series. Most reports follow some, but not all, of the proposed guidelines. A majority of the laboratories provided interpretations of the results in their reports. We found considerable variation in normal reference ranges. We describe this variation in detail for the CD4+ T-lymphocyte counts and CD4+ T-lymphocyte percentages. This article describes some of the TLI result report forms currently being used and identifies important quality issues in this rapidly expanding area of clinical laboratory testing.