Table 1.

Model input parameters.

Variable	Base Case Value (SD)	Range Examined	Reference
Baseline cohort characteristics
HIV prevalence (%)
Asymptomatic, chronic HIV+	11.4	2.6–17.6%	39
Symptomatic, chronic HIV+	5.2	1.2–8.0%	39
Acute, primary HIV infection	0.3	0.05–0.4%	Assumption
Total	16.9	3.9–26.0%	5, 29
Annual HIV incidence (%)	1.3	0.4–1.6%	5, 29
Age, mean years ± SD	32.8 ± 9.2		18
Male subjects (%)	54.6		18
HIV testing protocols
Average background HIV test frequency	Every 10 years	0–10 years, detection by OD	39
Sensitivity* (%)	99.6		37
Specificity* (%)	98.0		37
Test acceptance rate (%)	48.6	20–100	32
Rate of HIV-infected return for test results and linkage to care (%)	46.8	20–100	39
Distribution of initial CD4, mean cells/µl (SD)
Acute, primary HIV infection†	534 (164)		10
Chronic HIV infection‡	288 (331)	288–320	39
HIV RNA distribution (%)			35
>100,000 copies/ml	42.5	0–100
30,001 – 100,000 copies/ml	28.3	0–100
10,001 – 30,000 copies/ml	17.9	0–100
3,001 – 10,000 copies/ml	7.8	0–100
501 – 3,000 copies/ml	2.3	0–100
<500 copies/ml	1.2	0–100
Natural history of disease
Mean monthly CD4 cell decline by HIV RNA level (cells/µl)			17
>30,001 – 100,000 copies/ml	6.4
10,001 – 30,000 copies/ml	5.4
3,001 – 10,000 copies/ml	4.6
501 – 3,000 copies/ml	3.7
<500 copies/ml	3.0
Percent monthly risk of severe opportunistic diseases§ (%)			18
Bacterial	0.08–0.71
Fungal	0.02–2.22
Tuberculosis	0.21–1.96
Toxoplasmosis	0.00–0.06
Non-tuberculous mycobacteriosis	0.00–0.30
Pneumocystis jiroveci pneumonia	0.00–0.12
Other WHO stage 4-defining diseases	0.25–2.57
Percent monthly risk of mild opportunistic diseases (%)			18
Fungal	0.59–3.51
Other	2.51–3.10
Efficacy of co-trimoxazole (% reduction in probability of infection)
Severe bacterial	49.8		30, 38
Mild fungal infections‖	−46.4		30, 38
Toxoplasmosis	83.3		30, 38
Pneumocystis jiroveci pneumonia	97.3		42
Other WHO stage 4-defining diseases	17.9		30
Efficacy of ART (% patients with HIV RNA suppression, CD4 increase at 48 weeks)
First line (NNRTI + 2 NRTIs)	75%, 168 cells/µl	42%–84%	22, 23
Second line (PI + 2 recycled NRTIs)	75%, 168 cells/µl	35%–71%	22, 23
Stigma (quality of life decrement)¶
Test-associated stigma	0.08	0.00–1.00	27
Diagnosis-associated stigma	0.07	0.00–1.00	28
Discount Rate	3%	0%–3%	14
Costs (2006 US$)
HIV testing
Rapid HIV test	1.20	1–10 times base case	32
Confirmatory rapid test	1.78	1–10 times base case	32
Pre-test counseling	3.51	1–10 times base case	32
HIV care
Co-trimoxazole prophylaxis (monthly)	1.02		34
First-line ART (monthly)	18		36
Second-line ART (monthly)	49		36
Minor drug toxicity	11		18, 33, 34
Major drug toxicity	1,548		18, 33, 34
Routine care (range by CD4, monthly)	9.85–129.41	1–10 times base case	18, 31, 33
Inpatient hospital care, per day	221.14	1–10 times base case	33
Outpatient hospital care, per visit	11	1–10 times base case	33
CD4 count test	9	1–10 times base case	34
HIV RNA test	47	1–10 times base case	34

SD: Standard deviation; OD: Opportunistic disease; WHO: World Health Organization;

ART: Antiretroviral therapy; NNRTI: non-nucleoside reverse transcriptase inhibitor;

NRTI: nucleoside reverse transcriptase inhibitor; PI: protease inhibitor

^*Sensitivity and specificity refer to the characteristics of a single rapid test, not the confirmatory process; test specificity is assumed to be zero during the acute infection window period (approximately 2 months)

^†Starting CD4 cell count for incident cases

^‡Starting CD4 cell count, on average, for prevalent cases

^§Range indicated by CD4 count; details on risk by CD4 stratum are provided in the technical appendix.

^‖The percent monthly risk of mild fungal infections is increased by 46.4% in the presence of co-trimoxazole.³⁰

^¶Quality of life decrement reduces quality of life on a 0.00–1.00 scale where 1.00 represents perfect health and 0.00 represents death. By intentionally limiting quality of life decrements to these two forms of stigma (and assuming all other health states are “perfect” = 1.00), we bias results against HIV screening.