Baseline parameter values used in mathematical model
| Parameter | Value | Source |
|---|---|---|
| Adapted from Turner et al.14 | ||
| *Parameters drawn from a negative binomial distribution, mean, and dispersion. | ||
| Behavioural parameters | ||
| Preferred number of concurrent partners | 1 or 2 | |
| Proportion wanting 2 partners (<35 years old) | 0.05 | Assumption based on Kretzschmar model12 |
| Initial proportion of 16 year olds desiring short partnerships | Fitted to Natsal 200014,18 | |
| Men | 0.6 | |
| Women | 0.5 | |
| Proportion who switch from desiring short to long partnerships per year | Fitted to Natsal 200014,18 | |
| Men | 0.04 | |
| Women | 0.08 | |
| Mean duration of short partnerships (in days) | 14 | Assumption |
| Mean duration of long partnerships for 16 year olds (in days) | 900 | Fitted to Natsal 200014,18 |
| Increase in duration (in days) per year | 200 | Fitted to Natsal 200014,18 |
| Mean gap between partnerships (in days), (dispersion)* | 14 (2) | Assumption |
| Number of sex acts per day | Assumption based on Kretzschmar model12 | |
| Short partnerships | 1 | |
| Long partnerships | 0.25 | |
| Infection parameters | ||
| Transmission probability per sex act | 0.0375 | Fitted to Natsal 200017 and Adams et al4 |
| Duration, no treatment seeking (in days) | 180 | Assumption |
| Duration, treatment seeking (in days) | 30 | Assumption |
| Proportion seeking treatment | Fitted to Natsal 200017 and Adams et al4 | |
| Men | 0.0 | |
| Women | 0.045 | |
| Mean refractory period following treatment (in days), (dispersion)* | 7 (10) | Assumption based on CEG guidelines21 |
| Healthcare parameters (baseline) | ||
| Annual attendance rate at health care setting (proportion who report attending a healthcare setting in the last 12 months) | 0.85 | Chlamydia Recall Study20 |
| Probability of accepting screen | 0.5 | Assumption based on screening studies19,22 |
| Proportion of partners notified | 0.2 | Fitted to Natsal 200017 and Adams et al4 |
| Treatment efficacy (in those partner notified or screened) | 0.95 | Treatment guidelines23 |
| Mean delay (in days) before partner treatment (dispersion)* | 7 (10) | Assumption based on Recall Study (unpublished) |