Relative with status quo (approximately 1.18 million new infections over 20 years), universal screening with fourth-generation assay annually saved 2.32 million QALYs and cost $229.3 billion (2.74 million and $471.3 billion every six months); nucleic acid amplification testing saved 2.34 QALYs and cost $271.6 billion annually (2.76 million and $556.0 billion every six months). The incremental cost per QALY gained over status quo was $98,700 with annual fourth-generation assay ($172,200 every six months) and $116,300 with annual nucleic acid amplification testing ($201,800 every six months).
In the subgroup of men who had sex with men and injecting drug users, the incremental cost per QALY fell to $6,400 with annual fourth-generation assay ($8,300 every six months) and $6,900 with annual nucleic acid amplification test ($9,100 every six months). Even more favourable ratios were observed among men who had sex with men only: the incremental cost per QALY gained was $5,800 with annual fourth-generation assay ($7,900 every six months) and $6,400 with annual nucleic acid amplification testing ($8,800 every 6 months).
When compared with each other, six-month fourth-generation assay was generally cost-effective, although nucleic acid amplification testing may provide value-for-money in settings where undiagnosed HIV prevalence exceeds 4%.
Nucleic acid amplification test was generally more cost-effective than third-generation ELISA because of the longer window period between nucleic acid amplification testing and ELISA positivity.
The cost-effectiveness of fourth-generation assay improved with a shorter window period for this test, with a lower prevalence of HIV in the population of men who had sex with men, with a lower proportion of acute HIV infections, or with lower prices for immunoassay. Early initiation of antiretroviral treatment was another influential input.