Table 1. Variables and Sources.
| Variable | Base Case | Range | Source |
|---|---|---|---|
| Demographic variables | |||
| Age at presentation (mean ± SD) | 32.8±9.2 | 14-50 | Holmes16 |
| CD4 at presentation, cells/μl (mean ± SD) | 307±227 | 200-400 | Holmes16 |
| Viral load at presentation, log copies/ml (mean ± SD) | 5.0± 0.8 | 4-6 | Badri10 |
| Natural history variables | |||
| Mean monthly change in CD4 based on viral load (cells/μl) | Mellors, Rodriguez17, 18 | ||
| VL<500 | 1.67± 0.9 | ± 50% | |
| VL501-2000 | 3.33± 1.7 | ± 50% | |
| VL 2001-10,000 | 4.08± 2.1 | ± 50% | |
| VL 10,001-40,000 | 4.58± 2.4 | ± 50% | |
| VL >40,000 | 6.33± 3.2 | ± 50% | |
| Risk of developing severe opportunistic disease | Holmes, Badri16, 19 | ||
| CD4 <50 cells/μl | 10.5%/mo | ||
| CD4 51-200 cells/μl | 2.6%/mo | ||
| CD4 201-350 cells/μl | 1.1%/mo | ||
| CD4 >350 cells/μl | 0.26%/mo | ||
| Risk of death | Badri19 | ||
| CD4 <50 cells/μl | 2.1%/mo | ||
| CD4 51-200 cells/μl | 1.7%/mo | ||
| CD4 201-350 cells/μl | 1.1%/mo | ||
| CD4 >350 cells/μl | 0.8%/mo | ||
| Additional risk of death from severe opportunistic disease | Goldie12 | ||
| CD4 <50 cells/μl | 7.69%/mo | ||
| CD4 51-200 cells/μl | 4.48%/mo | ||
| CD4 201-350 cells/μl | 0.66%/mo | ||
| Treatment variables | |||
| Virologic suppression on HAART | |||
| 12 weeks | 84% | DART, Orrell, Coetzee15, 20, 21 | |
| 48 weeks | 72% | 50%-78% | |
| CD4 rise on first-line HAART | Battegay, Kaufmann, Lawn22-24 | ||
| First 6 months | 146 cells/μl | ||
| Months 7-12 | 46 cells/μl | ||
| Months 13-18 | 28 cells/μl | ||
| Months 19-24 | 21 cells/μl | ||
| Risk of HAART discontinuation due to toxicity | Robbins25, Orrell26, Calmy27, Amoroso28 | ||
| First line regimen 0-12 mo | 0.87%/mo | ± 50% | |
| First line regimen 12-36 mo | 0.25%/mo | ± 50% | |
| Second line regimen 0-12 mo | 1.8%/mo | ± 50% | |
| Second line regimen 12-36 mo | 0.42%/mo | ± 50% | |
| Utilization and cost variables | |||
| Annual number of inpatient days without a severe opportunistic disease | Badri et al10, 11 | ||
| CD4>350 (on/off HAART) | 0.14 / 1.9 | ± 50% | |
| CD4 201-350 (on/off HAART) | 0.39 / 3 | ± 50% | |
| CD4<=200 (on/off HAART) | 0.26 / 7.7 | ± 50% | |
| Annual number of inpatient days with a severe opportunistic disease | Badri et al10, 11 | ||
| CD4>350 (on/off HAART) | 0.37 / 5.7 | ± 50% | |
| CD4 201-350 (on/off HAART) | 0.52 / 10.8 | ± 50% | |
| CD4<=200 (on/off HAART) | 1.8 / 17.7 | ± 50% | |
| Annual number of outpatient visits | Badri et al10, 11 | ||
| CD4>350 (on/off HAART) | 4.3 / 4.1 | ± 50% | |
| CD4 201-350 (on/off HAART) | 3.9 / 5.0 | ± 50% | |
| CD4<=200 (on/off HAART) | 4.7 / 6.6 | ± 50% | |
| Costs (2007 USD) | |||
| Inpatient Day | $198 | $20-$200 | Badri; Cleary10, 29 |
| Outpatient visit | $30 | $3-$30 | Badri; Cleary10, 29 |
| Cost per viral load test* | $80 | $20-$140 | Badri, Elbeik10, 30 |
| Cost per CD4 test* | $25 | $5-$50 | Badri, Zijeneh10, 31 |
| First line HAART regimen (annual) | $322 | ± 50% | Badri, MSF10, 11, 32 |
| Second line HAART regimen (annual) | $640 | ± 50% | Badri, MSF10, 11, 32 |
*
Per test cost include an estimated cost of reagents, labor, parts, data management, and the rental or acquisition of the CD4 or viral load enumeration equipment.