92 and P = 0.26, respectively). RC after ARDFP did

not predict subsequent CD4 cell count and viral load changes 12 weeks following ARV treatment reinitiation (P = 0.90 and P = 0.29, respectively). We found no additional predictive value of replication capacity for virological or immunological responses (above what PSS provides) in patients undergoing salvage ARV treatment. In clinical trials of effective HIV combination antiretroviral (ARV) regimens, the majority of study participants maintained virological suppression for 3–7 years [1-3]. However, the proportion of patients experiencing treatment failure in real-life clinical settings is reported to be somewhat higher [4-6], and these patients have an increased risk of HIV disease progression. BAY 80-6946 ic50 Incomplete virological suppression is expected to lead to the emergence and Selleck Smoothened Agonist accumulation of drug-resistant strains, which might jeopardize the success of future treatment options [7-11]. It is therefore important to improve our understanding of the many factors that contribute to virological failure, and the factors that predict virological success with second-line options in patients experiencing treatment failure. In addition to genotypic

and phenotypic testing, replication capacity (RC) is regularly used by clinicians when deciding on the strategy for the management of these treatment-experienced

patients. A number of trials have determined that temporary interruption of ARV treatment is a strategy that leads to Ribonucleotide reductase rapidly increased plasma HIV RNA, decreased CD4 T-cell count and increased risk for clinical progression [12-14]. However, interruption of a failing regimen results in a rapid increase in viral susceptibility to ARV drugs, reflecting the re-emergence of a dominant wild-type viral population [15] concomitant with an increase in viral RC. The magnitude of that increase is inversely proportional to the baseline RC value [16]. The prognostic value of RC for subsequent ARV treatment response or disease progression has not been fully investigated. RC has been shown to be correlated with baseline CD4 cell count and viral load and to be a predictor of disease progression in ARV drug-naïve patients or those with limited prior ARV drug exposure, mostly in the pre-highly active antiretroviral therapy (HAART) era [17-20]. Further, RC has been shown to be a predictor of CD4 recovery in individuals with successful HIV RNA suppression on the first ARV regimen [21]. However, while RC is mostly used in the management of heavily treatment-experienced patients, there are limited published data on its predictive value for treatment outcomes of these patients in the HAART era [22, 23].