Trial designs for evaluating combination HIV prevention approaches.

Area of Science:

• Clinical Trials Methodology
• Epidemiology
• Public Health Interventions

Background:

• Combination HIV prevention strategies integrating biomedical and non-biomedical interventions show promise for improved health outcomes and reduced transmission.
• Evaluating the efficacy of combined interventions requires robust trial designs capable of assessing individual and synergistic effects.

Purpose of the Study:

• To compare the statistical properties and power of four trial designs: single-factor, multi-arm, all-in-one, and factorial.
• To determine the most effective trial design for assessing combination HIV prevention strategies, including biomedical (Treatment-as-Prevention, Pre-exposure Prophylaxis) and behavioral interventions.

Main Methods:

• Utilized Monte-Carlo simulations to model different trial designs.
• Simulations incorporated two biomedical interventions (TasP, PrEP) and three behavioral interventions (linkage-to-care, counseling, condom use).
• Considered various effect sizes, potential interactions between components, and sample sizes derived from real-world clinical studies.

Main Results:

• All-in-one and factorial designs demonstrated superior power for combination approaches compared to single-factor designs.
• Multi-arm designs were more powerful for evaluating single interventions.
• The factorial design exhibited consistent power across diverse scenarios and provided insights into component interactions.

Conclusions:

• Factorial and all-in-one designs are effective for assessing combination HIV prevention, particularly when components are expected to have complementary effects.
• The factorial design is preferred for combination regimens due to its power and ability to elucidate individual component contributions and interactions.
• Multi-arm designs remain valuable for evaluating single interventions independently.