Age- and Gender-Specific Estimates of Partnership Formation and Dissolution Rates in the Seattle Sex Survey
Received 29 May 2009; accepted 25 November 2009. published online 13 January 2010.
Purpose
Partnership formation and dissolution rates are primary determinants of sexually transmitted infection (STI) transmission dynamics.
Methods
The authors used data on persons' lifetime sexual experiences from a 2003–2004 random digit dialing survey of Seattle residents aged 18–39 years (N=1,194) to estimate age- and gender-specific partnership formation and dissolution rates. Partnership start and end dates were used to estimate participants' ages at the start of each partnership and partnership durations, and partnerships not enumerated in the survey were imputed.
Results
Partnership formation peaked at age 19 at 0.9 (95% confidence interval [CI]: 0.76–1.04) partnerships per year and decreased to 0.1 to 0.2 after age 30 for women and peaked at age 20 at 1.4 (95% CI: 1.08–1.64) and declined to 0.5 after age 30 for men. Nearly one fourth (23.7%) of partnerships ended within 1 week and more than one half (51.2%) ended within 12 weeks. Most (63.5%) individuals 30 to 39 years of age had not formed a new sexual partnership in the past 3 years.
Conclusion
A large proportion of the heterosexual population is no longer at substantial STI risk by their early 30s, but similar analyses among high-risk populations may give insight into reasons for the profound disparities in STI rates across populations.
aDepartment of Epidemiology, University of Washington, Seattle
bDepartment of Biostatistics, University of Washington, Seattle
cDepartment of Medicine, University of Washington, Seattle
dDepartment of Global Health, University of Washington, Seattle
eDepartment of Epidemiology, University of Michigan, Ann Arbor, MI
fU.S. Centers for Disease Control and Prevention, Atlanta, GA
gModelling and Economics Unit, Health Protection Agency Centre for Infections, London, UK
hMRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
Address correspondence to: Sara J. Nelson, MPH, University of Washington, Center for AIDS and STD, Harborview Medical Center, 325 9th Ave., Box 359931, Seattle, WA 98104. Tel: (206) 744-8055. Fax: (206) 744-3693.
ABSTRACT