Table 1.
Base-Case Parameter Values and Sensitivity Analysis Ranges Used in a Model of Partnership Formation, Times-at-Risk for Human Papillomavirus Infection, and Their Interactions
| Parameter | Value | Source of Derivation | Range of Sensitivity Analysis |
|---|---|---|---|
| Proportion of individuals in high sexual activity level | 0.07 | Chandra, 2011 (30)a | |
| Rate of partner change for low sexual activity level (per year) | 0.80 | Chandra, 2011 (30)b | 0.25–2.50 |
| Rate of partner change for high sexual activity level (per year) | 5.00 | —c | |
| Proportion of partnerships made exclusively with persons at the same sexual activity level (degree of assortativity ε) | 0.00 | (Proportionate mixing) | 0.00–1.00 |
| Rate of sex acts in partnerships (per year) | 75.40 | Mercer, 2013 (34) | |
| Proportion of time spent single | 0.25 | Demers, 2012 (35)d | |
| Duration of infection, years | 1.40 | Insinga, 2010 (31)e | 0.25–25.00 |
| Proportion of infections conferring natural immunity | 0.60 | Carter, 2000 (32) | |
| Duration of natural immunity, years | 10.00 | Wang, 2004 (33)f | |
| Probability of infection transmission per sex act with an infected person | 0.13 | Bogaards, 2010 (36)e ,g | 0.001–1.00 |
| Interaction effects (χi and φi) | 1.00 | (No interactions) | 0.05–7.76 |
Abbreviation: HPV, human papillomavirus.
a Based on having had more than 2 sexual partners in the last year.
b Average number among persons with 2 or fewer sexual partners in the last year.
c Manually set to achieve a 6% type-specific prevalence of HPV.
d Based on the proportion of individuals reporting being in a stable partnership.
e Averaged over HPV types.
f We assumed an exponential loss of immunity and found the rate of waning that led to 45% of individuals losing their seropositivity after 6.4 years.
g Calculated so that the average per-infected-partnership probability of infection was 0.79.