Backcalculation models of age-specific HIV incidence rates

Area of Science:

• Epidemiology
• Biostatistics
• Public Health

Background:

• Estimating past human immunodeficiency virus (HIV) infection incidence is crucial for understanding epidemic dynamics.
• Traditional backcalculation methods have limitations in accounting for evolving age distributions of infection.
• Age at infection influences disease progression, impacting incubation period estimates.

Purpose of the Study:

• To extend backcalculation methods for estimating age-specific HIV infection incidence.
• To incorporate age-dependent incubation periods into HIV incidence estimation.
• To analyze trends in HIV infection incidence across different age groups in the United States.

Main Methods:

• Developed a flexible backcalculation approach incorporating age-specific incubation distributions.
• Estimated age effects on HIV progression using joint analysis of natural history cohort data.
• Applied the refined method to US AIDS incidence data, adjusting for treatment effects and definition changes.

Main Results:

• Overall estimated HIV infection incidence in the US has declined since the mid-1980s peak.
• Individuals under 25 years old represent an increasing proportion of new HIV infections over time.
• This trend of younger age at infection was consistent across multiple incubation distribution models.

Conclusions:

• The enhanced backcalculation method provides valuable insights into age-specific HIV seroincidence trends.
• A notable shift towards younger ages at HIV infection is evident in the US epidemic.
• Findings highlight the need for targeted prevention strategies for younger populations.