Home collection kits for HIV testing: evaluation of three strategies for dealing with insufficient dried blood specimens.
Home collection kits allow individuals to obtain a blood specimen at home and send it to a laboratory for HIV testing. In preliminary studies, 15% of kit users submitted specimens considered to be insufficient for analysis. The current Public Health Service policy requires the laboratory to reject all such specimens entirely and request a second specimen, even though some specimens are sufficient to perform an enzyme immunoassay (EIA) but not a Western blot (WB) test. Using decision analysis, we evaluated three strategies to handle specimens sufficient to perform an EIA but insufficient to perform a WB analysis: current recommendation, or baseline, for which no test is preformed and "quantity not sufficient" is reported; alternative 1 , for which an EIA is done and reported as "negative" or "quantity not sufficient" (if initially reactive); and alternative 2, for which an EIA is done and reported as "negative" or "a reactive screening test" (if initially reactive). Baseline strategy requires all consumers with an initial specimen sufficient for EIA only to submit a second specimen, but either alternative requires fewer than 3% to submit a second specimen. Although 80% of consumers with an initial specimen sufficient for EIA learn their test results only with the baseline strategy, more than 99% learn their test results with either alternative. With the scenario of high (2%) HIV prevalence, 91% of consumers who would be told "reactive screening test" are truly infected. At a low (0.1%) HIV prevalence, 33% of consumers who would be told "reactive screening test" are truly infected. When a specimen is sufficient for EIA only, it is preferable to perform the EIA instead of rejecting the specimen, because many persons can get results from the initial specimen and because many fewer are required to submit a second specimen. Current policy should be reexamined in light of these findings.