Table 2.
Sensitivity analysis of potentially important model variables on the long-term effectiveness of genotype testing vs clinical judgement alone*
| Increase in Life Expectancy (months) | |
|---|---|
| Resistance to LPV/r after the initial regimen failure in genotype testing arm (vs 49.3% in the clinical judgement only arm) | |
| 49.3% | 10.3 |
| 41.9% (base case) | 10.5 |
| Efficacy of darunavir/r-containing regimen without enfuvirtide in patients with resistant strains to LPV/r in the clinical judgement alone arm | |
| 13% suppression, week 24 (base case) | 10.5 |
| 16% suppression, week 24 | 10.3 |
| 20% suppression, week 24 | 9.9 |
| Efficacy of darunavir/r- and enfuvirtide-containing regimen used in patients in genotype testing arm | |
| 63% suppression at week 48 (base case) | 10.5 |
| 78% suppression at week 48 | 14.2 |
| 95% suppression at week 48 | 18.3 |
| Proportion of patients with resistant strains to LPV/r in the clinical judgement alone arm who received a darunavir/r – and enfuvirtide-containing regimen after the first virological failure† | |
| 0% (base case) | 10.5 |
| 30% | 6.3 |
| 50% | 3.5 |
| A new class of HIV antiviral drugs available†† | |
| No (base case) | 10.5 |
| Yes, MK-0518 | 8.1 |
Life expectancies reported in this table are discounted.
Based on information from genotype resistance tests performed during earlier failures.
For this analysis, we hypothesized that MK-0518 would be available after the second antiretroviral regimen failure. In the clinical judgement alone arm and in patients in the genotype resistance testing arm who where sensitive to lopinavir/ritonavir (LPV/r) after the initial antiretroviral therapy (ART) regimen failure, the third ART regimen was assumed to be a darunavir/ritonavir MK-0518-containing regimen. In patients in the genotype resistance testing arm who were resistant to lopinavir/ritonavir after the initial ART regimen failure, the third ART regimen was assumed to be a MK-0518-containing regimen without darunavir. Efficacy data on a MK-0518-containing regimen were from the interim study results of a phase 2b, multicentre, randomized, double-blind, dose-ranging, placebo-controlled study that compared MK-0518 plus optimized background therapy (OBT) to placebo plus OBT in experienced patients [39]. The cost of MK-0518 was considered to be the same as that of darunavir.