Table 1.
Summary of Model Parameters.
| Parameter* | Population/Characteristic | Median (25th, 75th percentile) † | Distribution Form | Strength of Input‡ | References |
|---|---|---|---|---|---|
| Population size (N) |
Men 15–24 years 25–39 years Women 15–24 years 25–39 years |
22,076,120 33,757,505 21,025,717 33,171,851 |
N/A (unvaried) | II | (13) |
| Number of case reports (κ) |
Chlamydia Men 15–24 years 25–39 years Women 15–24 years 25–39 years Gonorrhea Men 15–24 years 25–39 years Women 15–24 years 25–39 years |
306,110 246,601 779,367 318,246 116,427 167,134 132,291 90,786 |
N/A (unvaried) | II | (1) |
| Case reporting fraction (ρ) § | 95.0% (93.8%, 96.2%) | Uniform | II | (14) Expert opinion |
|
| Proportion of cases that are asymptomatic (β) |
Chlamydia Men Women Gonorrhea Men Women |
83.9% (80.6%, 87.1%) 74.5% (71.6%, 77.5%) 41.3% (31.8%, 51.1%) 68.4% (61.8%, 74.2%) |
Uniform | III | (4) |
| Background screening percent (per year, σ) |
Men 15–24 years 25–39 years Women 15–24 years 25–39 years |
14.4% (13.5%, 15.3%) 17.6% (16.5%, 18.7%) 27.3% (26.1%, 28.4%) 31.1% (30.0%, 32.3%) |
Normal | II | (15) |
| Time to natural clearance (days, 1/ψ) |
Chlamydia Men Women Gonorrhea Men Women |
361.4 (313.9, 423.4) 397.9 (376.0, 416.1) 45.5 (38.6, 54.4) 91.3 (77.3, 108.6) |
Bootstrapped empirical data | III | (16, 18–26) |
| Time from infection to symptomatic treatment seeking (days, 1/τ) ǁ |
Chlamydia Men Women Gonorrhea Men Women |
25.5 (20.4, 30.7) 49.4 (39.7, 58.9) 16.2 (13.8, 18.4) 31.8 (27.5, 36.2) |
Composite: see Data Inputs Supplement | III | (4, 17); Unpublished data from the STD Surveillance Network (PS13–1306), 2016–2018 |
Not all parameters were used in all models. See the Data Inputs Supplement and Mathematical Modeling Supplement for more information on which parameters were used in which estimates.
The 25th and 75th percentiles were generated either parametrically by sampling from the listed probability distribution for each variable or non-parametrically using bootstrapping techniques. The details of this process are explained in the Supplemental Materials. For any variables with no uncertainty interval provided, no variability was assumed.
The strength of the inputs used to inform model parameters was assessed using a rating system adapted from Satterwhite, et al and Lefevre, et al, the criteria for which are provided in the Data Inputs Supplement. (7, 40s)
The case reporting fraction represents the proportion of all diagnosed cases that are reported to the Centers for Disease Control and Prevention.
The time from infection to symptomatic treatment seeking parameter is a function of multiple inputs. These included the probability of a person never seeking treatment, the time from infection acquisition to symptom onset, and time from symptom onset to testing due to symptoms. Refer to the Data Inputs Supplement for more information on how these components were combined to create this composite parameter.