An undetectable polymerase chain reaction signal in routine HIV plasma viral load monitoring is associated with better virological outcomes in patients receiving highly active antiretroviral therapy

Objectives The aim of the study was to assess whether patients with undetectable viraemia [a negative polymerase chain reaction result (PCRneg)] and those with plasma viral load (PVL) < 40 HIV-1 RNA copies/mL but a detectable (positive) PCR signal (PCRpos) had different outcomes in terms of the development of blips and virological failure (VF). Methods A multicentre observational database analysis was carried out. Data for patients whose highly active antiretroviral therapy (HAART) regime had been unchanged for ≥ 6 months by 1 January 2008, whose first two PVL measurements of 2008 were  40 copies/mL. Results Of the 1957 patients included in the study (mean age 47 years; median antiretroviral exposure 10.3 years), 1312 had BLPCRneg. Outcome events included 322 blips and 139 VFs, with incidence rates being significantly lower in patients with BLPCRneg than in those with BLPCRpos [13.0% vs. 23.4% (P < 0.0001) and 5.1% vs. 11.2% (P < 0.0001), respectively]. In multivariable analysis, BLPCRneg was associated with a reduced risk of blips [hazard ratio (HR) 0.58; 95% confidence interval (CI) 0.47–0.73; P < 0.0001] and VF (HR 0.44; 95% CI 0.31–0.62; P < 0.0001). Conclusions Patients with PCRneg had better virological outcomes than those with PVL < 40 copies/mL but detectable viraemia. This suggests that the ‘no-signal’ information provided by currently commercially available HIV RNA quantification assays should be used routinely.