Table 1.
Model parameters for base-case analysis.
| Parameter | Base-Case Estimate | Range for Sensitivity Analyses | Source |
|---|---|---|---|
| Probability of virologic failure a | |||
| Initial ART (over 12 months) | |||
| No PDR on NNRTI-based ART | 19.2% | 16.8–24.6% | Boerma et al. [28], Kityo et al. [2] |
| PDR on PI-based ART | 19.2% | ||
| PDR on NNRTI-based ART | 64.1% | 39.5–75.2% | |
| Dolutegravir-based ART | 9.1% | Boerma et al. [28], Dugdale et al. [40] |
|
| Second-line ART (over 24 months) | |||
| PI-based ART after NNRTI-based first-line ART | 16.4% | 13.9–19.4% | Boerma et al. [41] |
| PI-based ART after DTG-based first-line ART | 16.4% | 13.9–40.0% | Assumption |
| Cascade of care | |||
|
Status quo probability of switching to second-line ART when virologic failure is diagnosed b |
40% | Assumption | |
| Probability of switching to second-line ART when virologic failure is diagnosed with improved regimen switching practices | 80% | 60.0–90.0% | |
| Probability of lost to follow-up (over 5 years) c | 15% | Carlucci et al. [42] | |
| Unit Costs (USD) d | |||
| ART annual cost | |||
| NNRTI-based ART | $123 | Global Fund [43] | |
| Dolutegravir-based ART | $123 | Assumption | |
| PI-based ART | $290 | $123–$400 | Global Fund [43] |
| Inpatient day | $96 | $15–$400 e | IHME [44,45,46,47], WHO-CHOICE [48] |
| Outpatient visit | $32 | $10–$80 | IHME [44,45,46,47], WHO-CHOICE [48] |
| CD4 testing | $12 | $6–$24 | Duarte et al. [23] |
| Viral load testing | $54 | $10–$80 | Duarte et al. [23] |
| Resistance testing | $125 | $30–$250 | Duarte et al. [23] |
aSupplemental Material Sections 2C, 2D, and 2E discuss how sources were used to inform assumptions regarding probability of virologic failure on various antiretroviral therapy (ART) regimens. In the base-case scenario, the ratio of the odds of virologic failure for those with pretreatment drug resistance (PDR) on non-nucleoside reverse transcriptase inhibitor (NNRTI)-based ART compared to those with either no PDR on NNRTI-based ART or those with PDR on protease inhibitor (PI)-based ART is 7.5. We explored a one-way sensitivity analysis in which we varied the odds ratio from 2.0 to 15.0. An odds ratio of 2.0 corresponds to a probability of virologic failure for those with PDR on NNRTI-based ART of 39.5% and a probability of virologic failure for those with no PDR on NNRTI-based ART of 24.6%. An odds ratio of 15.0 corresponds to a probability of virologic failure for those with PDR on NNRTI-based ART of 75.2% and a probability of virologic failure for those with no PDR on NNRTI-based ART of 16.8%. b Supplemental Material Section 2A discusses data used to inform our assumption regarding the status quo probability of switching to second-line ART when virologic failure is diagnosed. c Supplemental Material Section 2F discusses how sources were used to inform assumptions regarding lost to follow-up. d Supplemental Material Section 3 discusses how sources were used to inform assumptions regarding unit costs. e This range is meant to capture uncertainty in both unit cost per inpatient day and the number of inpatient days per clinical event (see Supplemental Material Section 3B for details).