Stability of HIV RNA in plasma stored at different temperatures

In resource-limited settings plasma is usually transported to centralized laboratories for HIV RNA quantification; often by motor vehicles using dry ice. Any decay in plasma HIV RNA when near the threshold used to define virologic failure could impact clinical management. However, maintaining a cold chain during transport can be costly and limit the frequency of shipments, which can delay clinical assessments and also negatively impact patient care. Transporting plasma at ambient temperatures could facilitate timely measurements of plasma HIV RNA viral loads (VL). We conducted a stability study of HIV RNA in plasma held for 1, 3, 5, and 7 days at a range of temperatures (4{degrees}C, 30{degrees}C, and 37{degrees}C) to simulate the durations and temperatures specimens could experience during transport. Thirteen large volume plasma specimens with VL ranging from 2.7-5.53 log10 copies/mL were evaluated. Mean changes in VL between Day-0 to Day-1, Day-3, Day-5 or Day-7 were calculated, with decays >0.5 log10 c/mL considered clinically relevant. Compared to Day 0, the VL of plasma stored at 4{degrees}C and 30{degrees}C remained stable across the Days tested. The VL in plasma stored at 37{degrees}C had a progressive decline at Day-1, Day-3, Day-5 and Day-7 (means of -0.04, -0.19, -0.33. -0.34 log10 c/mL, respectively), with a decay of >0.5 log10 observed in 3/13 (23%) specimens at Day-7. A linear regression analysis showed that plasma specimens stored at 37{degrees}C significantly decayed over time (slope -0.054, 95% CI -0.079, -0.029; p=0.01). Any decay observed among specimens stored at 4{degrees}C and 30{degrees}C was not clinically relevant nor statistically significant. Our observations suggest that HIV RNA levels in plasma should remain stable if transported to centralized laboratories at ambient temperatures of [≤]30{degrees}C or chilled by cold packs over a period [≤]7 days. Transporting specimens with cold packs instead of dry ice could reduce costs and facilitate the timely monitoring of VL used to assess and guide antiretroviral therapy.