Cost-effectiveness of provider-based HIV partner notification in urban Malawi

Abstract

Provider-initiated partner notification for HIV effectively identifies new cases of HIV in sub-Saharan Africa, but is not widely implemented. Our objective was to determine whether provider-based HIV partner notification strategies are cost-effective for preventing HIV transmission compared with passive referral. We conducted a cost-effectiveness analysis using a decision-analytic model from the health system perspective during a 1-year period. Costs and outcomes of all strategies were estimated with a decision-tree model. The study setting was an urban sexually transmitted infection clinic in Lilongwe, Malawi, using a hypothetical cohort of 5000 sex partners of 3500 HIV-positive index cases. We evaluated three partner notification strategies: provider notification (provider attempts to notify indexes' locatable partners), contract notification (index given 1 week to notify partners then provider attempts notification) and passive referral (index is encouraged to notify partners, standard of care). Our main outcomes included cost (US dollars) per transmission averted, cost per new case identified and cost per partner tested. Based on estimated transmissions in a 5000-person cohort, provider and contract notification averted 27.9 and 27.5 new infections, respectively, compared with passive referral. The incremental cost-effectiveness ratio (ICER) was $3560 per HIV transmission averted for contract notification compared with passive referral. Provider notification was more expensive and slightly more effective than contract notification, yielding an ICER of $51 421 per transmission averted. ICERs were sensitive to the proportion of partners not contacted, but likely HIV positive and the probability of transmission if not on antiretroviral therapy. The costs per new case identified were $36 (provider), $18 (contract) and $8 (passive). The costs per partner tested were $19 (provider), $9 (contract) and $4 (passive). We conclude that, in this population, provider-based notification strategies are potentially cost-effective for identifying new cases of HIV. These strategies offer a simple, effective and easily implementable opportunity to control HIV transmission.

Keywords: Cost-benefit analysis; HIV; contact tracing; sub-Saharan Africa.

Figure 1

Decision tree modelling three strategies for partner notification. Partners of index patients may be notified of their exposure to HIV by provider notification, contract notification or passive referral. Partners who return to the clinic and agree to HIV testing may test positive or negative, and those partners who test positive may be in the chronic phase of infection and not treatment eligible, or may be eligible for treatment (CD4 ≤250 cells/mm³). Persons who test and are HIV negative may change their sexual risk behaviours, affecting their risk of acquisition in their serodiscordant partnership with the index partner. Transmission probabilities from positive partners account for the variability of infectivity at different stages of infection, as well as reduced infectiousness for those who are eligible and retained on ART. Transmission also accounts for the probability of HIV-infected partners in the cohort having sexual partnerships with HIV-negative persons outside of the index partnership.

Figure 2

ICER planes. (a) Contract notification vs passive referral. (b) Provider notification vs contract notification. (c) Provider notification vs passive referral. The probabilistic sensitivity analysis simultaneously varies the input parameters across a given range of values from the parameter’s distribution. With each draw, a new incremental cost and incremental effectiveness is calculated, as compared with the next least expensive arm. The resulting point estimates represent the ICERs of the 5000 draws executed with probabilistic sensitivity analyses. In (a) contract notification is compared with passive referral. In (b) the next most expensive option (provider notification) is compared with contract notification. Finally, in (c) we compare provider notification with passive referral.