Table 4.

Key parameter values for sensitivity analysis of numerical example of antiretroviral therapy (ART) and preexposure prophylaxis (PrEP) for MSM

Parameter	High PrEP Efficacy	Shorter Time Horizon	Rapidly Growing Epidemic	Source
Time Horizon
Time horizon for program implementation, years, T	20	5	20	Assumed
Program Constraints
Minimum acceptable ART scale up level, $x_1^{\mathit{\text{min}}}$	50,000	10,000	10,000	Assumed
Maximum feasible ART scale up level, $x_1^{\mathit{\text{max}}}$	400,000	100,000	100,000	Assumed
Minimum acceptable PrEP implementation level, $x_2^{\mathit{\text{min}}}$	10,000	2,000	1,000	Assumed
Maximum feasible PrEP implementation level, $x_2^{\mathit{\text{max}}}$	3,000,000	1,000,000	500,000	Assumed
Health Benefits
Net present QALYs gained per person starting ART, a1	15.53	7.64	28.94	Calculated
Net present QALYs gained per person starting PrEP, a2	2.04	0.199	2.91	Calculated
Net present infections averted per person starting ART, b1	0.873	0.269	1.98	Calculated47, 51, 53
Net present infections averted per person starting PrEP, b2	0.089	0.004	0.160	Calculated9, 47, 49, 51, 53
Net present QALYs gained from receiving ART, qtx	5	5	5	10
Net present QALYs gained from avoiding infection, qIA	9	9	9	10, 62
Chance of acquiring HIV in T years, σT	14.6%	3.9%	24.5%	Calculated47, 51, 52
ART efficacy in reducing sexual infectivity, εtx	90%	90%	90%	3, 63, 64
PrEP efficacy in reducing the chance of HIV acquisition, ε2	73%	44%	44%	9
Costs
Budget for HIV spending, B	$10 billion	$2.5 billion	$5 billion	Estimated55
Net present cost of starting one person on ART, C1	$118,100	$179,490	$13,800	Calculated
Net present cost of starting one person on PrEP for T years, C2	$134,139	$44,449	$127,404	Calculated
Net present savings from averting an HIV infection, sIA	$70,000	$70,000	$70,000	10, 62
Net present lifetime cost of ART for one person, c1	$200,000	$200,000	$200,000	10
Net present cost of PrEP for one person for T years, c2	$150,000	$46,000	$150,000	Calculated10
Overlap constant* for QALYs gained, kQ	2.39E-06	3.80E-07	2.32E-05	Calculated (see Appendix)
Overlap constant* for infections averted, kIA	2.51E-07	3.54E-08	2.13E-06	Calculated (see Appendix)
Discount rate for costs, QALYs and new infections, r	3%	3%	3%	34

Note: ART = antiretroviral therapy; PrEP = preexposure prophylaxis; QALY = quality-adjusted life year

^*Assumes overlap functions of the form δ_Q(x) = k_Qx₁x₂ and δ_IA(x) = k_IAx₁x₂.