Table 2.

Selected key model parameters.

	Distribution and value	Source
HIV-related mortality	Double Weibull	B2C
Shape 1	1.340
Scale 1	0.199
Shape 2	0.719
Scale 2	40.557
Weight of 1st component	0.031
Official transfer out	Weibull	B2C
Shape	1.015
Scale	8.196
Self-transfer out	Weibull	B2C
Shape	1.637
Scale	32.813
Changing to alternative ART sources	Weibull	B2C
Shape	1.207
Scale	21.785
ART discontinuation	Weibull	B2C
Shape	0.666
Scale	43.102
Probabilities of missing an event		B2C
Death	0.583
Official transfer out	0.140
ART discontinuation	0.900
Spontaneous return	Exponential	assumption
Rate	0.333
Probability to be found by tracing		B2C
If discontinued ART or on irregular ART	0.700
Return after tracing if discontinued ART	Weibull	B2C
Shape	0.476
Scale	2.74
Return after tracing if on irregular ART	Weibull	B2C
Shape	0.574
Scale	0.599
Partner change		assumption
Rate	1
Frequency of sex acts		assumption
Acts per year	100
Per-act probability of transmission		From Wilson et al.5
Male to female, viral load 10 copies/ml	4.3*10−5
Female to male, viral load 10 copies/ml	2.2*10−5
Risk ratio per 1 log10 increase in viral load	2.45

ART, antiretroviral therapy; LH, Lighthouse Clinic (longitudinal data from leDEA Southern Africa database); B2C, Back-to-Care tracing programme⁷. Weibull distribution is parameterised using the following formula for cumulative incidence (CI): $Cl\left(t\right)=1-e^{-{\left(\frac{t}{\lambda }\right)}^k}$, where k is the shape parameter and λ the scale parameter. Double Weibull distribution is a mixture of two Weibull distributions.