A number of studies have provided clinical evidence
of the ability of phenotypic testing to aid treatment decisions, predict
virological response and to improve virological outcome:
A pilot study has
demonstrated a significant correlation between baseline phenotypic drug susceptibility
and virological outcome [Deeks et al.,
J Infect Dis 1999, 179:1375-81].
A retrospective analysis in patients with a mega-HAART regimen has
shown that phenotypic drug sensitivity at baseline was strongly associated
with virological outcome at 24 weeks [Miller et al., Antiviral Ther
2000, 5:49-55].
A meta-analysis of 12 studies (10 retrospective studies and 2 prospective
studies) using a standardised data analysis plan has confirmed the
importance of phenotypic testing as a predictor of virological failure
[de Gruttola et al., Antiviral Ther 2000, 5:41-8].
In various studies, phenotypic testing has confirmed its usefulness
in guiding optimal treatment regimens [Perez-Elias et al., AIDS 2000,
14:F95-101; Petropoulos et al., Antimicrob Agents Chemother 2000, 44:920-8;
Walter et al., Antiviral Ther 2000, 5:249-56; Cohen et al., 4th International
Workshop on HIV drug resistance and treatment strategies 2000, Abs
84; Verbiest et al., Antiviral Ther 2000, 5 (Suppl 2):28].
Specifically for protease inhibitors, phenotype may be a better predictor
than genotype [Piketty et al., AIDS 2000, 14:626-8].
The first economic evaluation showed that phenotypic testing in HIV-infected
patients failing HAART regimens reduced treatment costs and appeared
cost-effective [Verbiest et al., Antiviral Ther 2000, 5 (Suppl 2):28].
More recently, phenotypic testing has predicted sustained long-term
virologic suppression better than treatment history [Call et al., J
Infect Dis 2001, 183:401-8]
