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Background:  Patients with optimally suppressed plasma HIV-1 RNA concentrations occasionally experience transient increases in HIV-1 RNA, commonly referred to as “blips.” This may be the result of factors such as short treatment interruption, development of drug resistance, intermittent illness, or recent immunization. It has been reported that falsely elevated HIV-1 RNA levels are associated with the use of Plasma Preparation Tubes™ (PPT). We observed that patients at Northwestern Memorial Hospital (NMH) experienced blips during a period of time (January to August 2003) when the HIV-1 RNA specimen collection procedure changed from using standard ethylenediaminetetraacetic acid (EDTA) tubes to PPT tubes. Prior to and after this period, specimens were collected in EDTA tubes. We investigated whether transient HIV-1 RNA elevations were related to the type of tube used for plasma collection. 

Methods:  The CDC NMH HIV Out-Patient Study (HOPS) database was surveyed to determine the frequency of blips during periods of PPT or EDTA tube use for plasma HIV-1 RNA collection. Patients with ≥ 3 undetectable HIV-1 RNA levels (< 50 copies/mL, Roche Ultrasensitive Amplicor^® v1.0 or 1.5) during the initial period of EDTA use and ≥ 1 HIV-1 RNA measurement during the periods of PPT and resumed EDTA use were evaluated. 

Results:  Of 595 NMH HOPS patients, 68 had optimally suppressed HIV-1 RNA prior to the switch to PPT tubes and ≥ 1 measurement during PPT and resumed EDTA tube use. HIV-1 RNA blips (range 50 to 1779, mean 267 copies/mL) occurred in 53% (n = 36) of patients during the period of PPT use, 7% (n = 5) during both EDTA and PPT periods, and in only 6% (n = 4) during EDTA tube use (p = 0.002). Of patients maintained, 25% suppressed HIV-1 RNA levels without blips. Viral blips resulted in 43% (19 of 45) of patients with ≥ 1 unplanned repeat blood draws for HIV-1 RNA measurement. At least one patient had an ART regimen change because of the blip.  

Conclusions:  The use of PPT tubes for plasma HIV-1 RNA measurement resulted in a viral “blip” in > 50% of patients. This prompted early and not clinically indicated repeat blood draws for HIV-1 RNA testing and additional clinic visits, as well as a medication change in at least 1 patient. Although processing of PPT tubes is considered safer, the increased costs related to blips indicate that PPT tubes should not be used for HIV-1 RNA monitoring in maximally suppressed HIV-infected patients or in clinical trials where HIV-1 RNA is a clinical endpoint.

Keywords: HIV RNA; Treatment monitoring ; Viral rebound