Background: Advances in molecular biology and changes in microbial nomenclature may subject diagnostic microbiology to errors. A patient diagnosed with Pneumocystis jiroveci pneumonia and then with AIDS had received a negative "AIDS test"--"negative for antibodies to HTLV 1 and 2." The test requisition showed that the physician had requested HTLV-I/II testing but not an HIV-1/2 test. A root cause analysis was performed to determine if the erroneous testing represented a systemic problem. A study was conducted to identify and address such testing errors.
Methods: For the 1,952 HTLV-I/II test requests in a 17-month period in the Southern Alberta region, a random representative sample of 555 requests for HTLV-I/II testing were evaluated for appropriateness. Physicians ordering "inappropriate" tests were surveyed to determine root causes, and the HTLV-I/II check box was subsequently removed from the requisition.
Results: Some 318 (94%) of the 340 clinically directed HTLV tests were likely or definitely inappropriate--that is, only an HIV-1/2 test was required. At least 81% (127/156) of the 8% (156/1,948) of the HTLV-I/II tests ordered without an HIV-1/2 test concurrently were ordered inappropriately. In the telephone survey, all 69 physicians suspected to have incorrectly ordered HTLV-I/II tests reported erroneously requesting HTLV for HIV. A root cause analysis identified confusing viral nomenclature, diagnostic testing menu, and form design as contributing factors. A requisition recall and redesign has reduced erroneous laboratory testing.
Conclusions: A high proportion of HTLV-I/II tests were ordered erroneously and confused with HIV-1/2. Careful attention to routine test menus and form design, including the exclusion of rare and confusing pathogens, reduces risk of error for practicing physicians.