Fig 1.
Dynamic compartmental HIV transmission model schematic diagram.
For each city, the adult population aged 15–64 was stratified into compartments on the basis of (1) gender (male or female), (2) race/ethnicity (black/African American, Hispanic/Latino, and non-Hispanic white/others), and (3) HIV risk behavior type (men who have sex with men (MSM), people who inject drugs (PWID), MWID, and heterosexual (HET)). MSM, MWID, and HET were further stratified into subgroups based on HIV sexual risk behavior intensity (high vs low), and PWID and MWID were categorized based on whether they were receiving opioid agonist treatment (OAT). Individuals within each of these 42 strata (MSM: 6 groups, MWID: 12 groups; PWID: 12 groups; HET: 12 groups) progress through the model according to the 19 health states illustrated above. Prior to HIV infection, HIV-negative individuals can be screened for HIV (screened in past 12 months), and screened MSM or MWID can take pre-exposure prophylaxis (PrEP). HIV transmission can occur through three modes: heterosexual contact, homosexual contact, and needle-sharing. We specified the pattern of sexual mixing between risk groups and race/ethnicity, where assortativity determines the proportion of sexual contacts within the same group, and we varied the level of assortativity across cities (28). Following HIV infection, individuals transition through acute infection (3 months), then are classified as infected but not diagnosed, diagnosed but ART-naïve, and on- or off-ART, and partitioned according to CD4 cell count (CD4 ≥ 500, 200–499, and <200). Health state transitions occur at monthly intervals, with transition to death a possibility from each of the health states depicted, with varying probabilities.
Fig 2.
Model parameter category proportions.
The boxes are proportionally scaled to the corresponding model parameter category sizes. Model parameter category labels: Population estimates ‒ 1. Initial HIV-negative and HIV-infected population estimates; HIV transmission ‒ 2. Parameters used to calculate the probability of HIV transmission; Treatment and HIV disease progression ‒ 3. Screening, diagnosis, treatment and HIV disease progression; Prevention ‒ 4. HIV prevention programs, including syringe service programs (SSP), OAT, and PrEP; Costs ‒ 5. The costs of medical care for HIV-negative and HIV-infected individuals; and QALYs ‒ 6. Health utility weights for each stage of HIV disease progression. ART: Antiretroviral treatment; All Pop.: Census population estimates; QALYs: Quality-adjusted life-years; Mixing: Sexual mixing patterns.
Table 1.
Summary of model parameters and evidence quality ranking.
Table 2.
Data sources used for each risk group, by model parameter category.
Table 3.
Primary analyses data sources and analytic methods†.
Table 4.
Quality assessment for model parameters common across cities.
Fig 3.
Heterogeneity in selected parameter estimates by city, risk group, gender and race/ethnicity.
MSM: Men who have sex with men; PWID: People who inject drugs; HET: Heterosexuals; ART: Antiretroviral treatment; F: Female; M: Male.
Fig 4.
Coverage of sterile syringes programs for people who inject drugs.