Table 1.

List of selected simulation parameters and calibration targets

Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) parameters	Value	Reference
Proportion of cases symptomatic*
Urethral	0.74	30
Rectal	0.20	31 32
Pharyngeal	0.10	32 33
Duration of infection (at each site) in the absence of treatment	(3–12) months†	4 34–47
Coefficient of NG/CT transmission per week	0.294	Calibrated to provide the incidence of NG/CT
Proportion of NG/CT infections occurring at each site		Calibrated to provide the site-specific incidence of NG/CT
Urethral	0.35
Rectal	0.49
Pharyngeal	0.16
Increase in HIV transmissibility (for those with urethral or rectal infection)	(1.5–2) fold*	5 48–51
Increase in HIV susceptibility (for those with urethral or rectal infection)	(1–2.5) fold*	33 34 51 52

NG/CT calibration targets	Mean‡ (Range)
Number of annual NG/CT diagnosis among MSM in Baltimore City		Values estimated from local data on gonorrhoea surveillance and STI clinic visits in Baltimore City (see section 2 in the online supplementary material)
Urethral	337 (269–405)
Rectal	25 (18–33)
Pharyngeal	42 (23–60)
Site-specific annual number of incident NG/CT cases among MSM in Baltimore City
Urethral	944 (753 – 1135)
Rectal	1251 (998 – 1505)
Pharyngeal	409 (326 – 492)

HIV parameters
Disease duration
Acute	(6–9) weeks*	53 54
Chronic	(8–10) years*	55 56
Late stage§	(1–3) years*	55–57
Mortality rate‡
Acute and chronic, no ART	5 per 1000 person-years	58–60
Late stage, no ART	1/duration of late stage
Reduction in mortality due to ART	0.58
Time from ART discontinuation to pre-ART CD4 nadir¶	ART treatment duration up to 1 year	61–64
Time from ART initiation to full viral suppression	(4–24) weeks*	29
Average viral load (log10 copies/mL)		55
Acute, no ART	6.5
Chronic, no ART	4.5
Late stage, no ART	5
On ART, partially suppressed	3.5
On ART, fully suppressed	1.5
Infectiousness per sexual contact	2.45(log(VL)-4.5)	55
Weekly probability of engagement in HIV care	0.006	65–67
Weekly probability of ART discontinuation	0.015	68
Gap in care after ART discontinuation	26 weeks	69
Relative probability of accessing HIV care among black MSM compared with white MSM	0.5	70

HIV calibration targets
HIV prevalence	0.22 per 100 000 person-year	71
HIV continuum of care: proportion of cases		71
Diagnosed	0.86
Linked to care	0.62
Engaged in care	0.5
On ART	0.39
Virally suppressed	0.27

*Values represent a pooled estimate of the reported measures for NG and CT infections.

†Values are selected over uniform distributions across the ranges presented.

‡Values represent the reported levels of NG/CT diagnosis among Baltimore City’s MSM, and they are likely to underestimate the proportion of ongoing rectal and pharyngeal infections. We, therefore, consider such potential underestimation in estimating the annual incidence of NG/CT (see section 2 of the online supplementary material) and have calibrated the model to represent realistic levels of prevalence (see the section on population overview in the main text).

§Mortality rate in late stage is defined as 1/(duration of late-stage disease).

¶Infectiousness assumed equal to that of the chronic disease.

ART, antiretroviral therapy; MSM, men who have sex with men; STI, sexually transmitted infection.