Table 1. Input parameters for model-based analyses.
| Variable | Base Case Value | Range Examined | Reference |
| Baseline cohort characteristics | |||
| Undiagnosed HIV prevalence (%) | [10] | ||
| Total | 0.4 | 0.1–1.0 | |
| Age, mean years (SD) | 37 (14) | 27–47 | [10] |
| Sex | [10] | ||
| Male (%) | 35 | ||
| Distribution of initial CD4, median cells/µl (IQR, SD) | |||
| Chronic HIV infection* | 467 (606, 471) | [10] | |
| Discount Rate (annual) | 3% | 0–3% | |
| HIV RNA distribution in chronic HIV infection (%) | [15], [31] | ||
| >100,000 copies/ml | 12.9 | ||
| 30,001–100,000 copies/ml | 12.9 | ||
| 10,001–30,000 copies/ml | 25.0 | ||
| 3,001–10,000 copies/ml | 25.2 | ||
| 501–3,000 copies/ml | 16.3 | ||
| <500 copies/ml | 7.7 | ||
| HIV testing protocols | |||
| Average background HIV test frequency | Every 5 yrs | Every 3–7 yrs | [8] |
| Sensitivity† (%) | 99.6 | [8], [32]–[35] | |
| Specificity† (%) | 97.5 | [8], [32]–[35] | |
| Provider strategy | |||
| Test offer probability (%) | 36 | 30–100 | [10] |
| Test acceptance probability (%)‡ | 75 | 30–100 | [10] |
| Probability of HIV-detected to link to care (%) | 80 | 50–100 | [10] |
| Counselor strategy | |||
| Test offer probability (%) | 80 | 30–100 | [10] |
| Test acceptance probability (%)‡ | 71 | 30–100 | [10] |
| Probability of HIV-detected to link to care (%) | 80 | 50–100 | [10] |
| Costs (2009 US$) | |||
| Routine care (range by CD4, monthly) , off ART | 290–2,380 | [37]–[39] | |
| Routine care (range by CD4, monthly), on ART | 240–1,080 | [37]–[39] | |
| CD4 test | 70 | [40] | |
| HIV RNA test | 120 | [40] | |
| Acute OI events | [37]–[39] | ||
| Pneumocystis jiroveci pneumonia | 13,120 | ||
| Mycobacterium avian complex | 5,620 | ||
| Toxoplasmosis | 31,320 | ||
| Cytomegalovirus | 8,010 | ||
| Fungal infections | 8,930 | ||
| Other opportunistic infections | 6,010 | ||
| Mortality (treated and untreated patients) | [37]–[39] | ||
| Any OI event | 93,990 | ||
| Chronic AIDS | 59,670 | ||
SD: Standard deviation; IQR: Inter-quartile range; OI: Opportunistic infection.
*Starting CD4 cell count, on average, for prevalent cases.
†
Sensitivity and specificity refer to the characteristics of a single rapid test, not the confirmatory process; test sensitivity is assumed to be 2.5% (the false positive rate) during the acute infection window period (approximately 2 months).
‡
Probability of test acceptance is conditional upon being offered a test.