Table 1.

Inputs into computer simulation after calibration.

Variable	Value	Source
Characteristics of initial progression model cohort
Mean age, years	39 (SD 9)	[2]
Mean CD4+ cell count (cells/μl)	126 (SD 127)	[2]
Mean viral load (Log 10 units)	4.5 (SD 1)	[2]
% Male	38%	[2]
Probabilities and rates
Probability of adherence to ART regimen	0.85	[5]
Probability that mutation potentially causing resistance, results in resistance, NRTI or PI	0.50	[6]
Probability mutation potentially causing resistance, results in resistance, NNRTI	0.90	[6]
Probability of cross-resistance to other NRTI, given NRTI mutation conferring resistance (zidovudine or stavudine)	1.0	[6]
Probability of cross-resistance to other NRTI, given NRTI mutation conferring resistance (other)	0.48	[6]
Probability of cross-resistance to other PI, given PI mutation causing resistance	0.24	[6]
Probability of cross-resistance to other NNRTI, given NNRTI mutation causing resistance	0.88	[6]
Rate of accumulating resistance mutations, per year	0.18	[7]
Viral load decrement with cART consisting of nevirapine + 2 NRTIs (100% adherence)	2.22	[8]
Viral load decrement with cART consisting of boosted PI (100% adherence)	2.68	[8]
Utilities
Decrease in utility with cART	0.053	[8]
Utility with CD4+ cell count <100 cells/μl	0.81	[9]
Utility with CD4+ cell count between 100 and 200 cells/μl	0.87	[9]
Utility with CD4+ cell count 200 cells/μl and above	0.94	[9]
HIV epidemiology and transmission
Population at start of calibration	20 479 400	[10]
Age range, years	0–50
Adult HIV prevalence (1997)	10.60%	[11]
Probability of transmission per sex acta	0.000067–0.0073	[12,13]
Untreated non-HIV STI prevalence	6%	[14]
Probability of HIV testing (per annum)	16%	[15–17]
Probability of linkage to HIV care and treatment	68%	[18]
Calibration parametersb
Multiplier on probability of transmission per sex act	1.71
Multiplier on HIV mortality	0.47
Sexual risk behaviors
Proportion abstinent (M/F) - Class 1	5%/10%	[19–23]
Proportion in stable, monogamous relationship (M/F) - Class 2	31%/69%	[23–25]
Proportion in multiple, concurrent relationships (if nonmonogamous) (M/F) - Class 3	56%/17%	Assumption
Proportion in multiple, concurrent relationships (if nonmonogamous) (M/F) - Class 4	8%/4%	[26,27]
Desired frequency of sex acts (per year)f	104	Assumption
Duration of relationshipc	0.5 to 3 years	Assumption
Median number of concurrent partners (Class 3)	3	[25]
Median number of concurrent partners (Class 4)	10	[25]
Probability of consistent condom use	34%	[28]
Relative risk of unsafe sex (condom nonuse most or all of the time) if aware of HIV status	0.47	[29]
Costs (2008 US$)
Cost of outpatient care, annually, without cART ($/month)	$288	[2]
Cost of care per hospitalization	$390	[2]
Cost of cART, annually, first regimend	$189	[2]
Cost of cART annually, second regimene	$1361	[2]
Cost of viral load test	$70	[2]
Cost of CD4+ cell test	$11	[2]

cART, combination antiretroviral therapy; NNRTI, nonnucleoside reverse transcriptase inhibitor; NRTI, nucleoside reverse transcriptase inhibitor; PI, protease inhibitor.

^aTransmission probability varies according to both sex (M/F) and HIV viral load of the infected person. These values are adjusted by a multiplier during calibration.

^bVaried during model calibration.

^cDuration dependent upon class of sexual risk behavior with stable, monogamous relationships having the longest duration and multiple, concurrent relationships having the shortest.

^dFirst-line cART regimen consists of nevirapine + either zidovudine or stavudine + other NRTI.

^eSecond-line cART consists of a boosted PI + two NRTIs other than those in initial regimen.

^fSee Appendix A – Technical Appendix for description of partner balancing algorithm, http://links.lww.com/QAD/A428.