Cost-effectiveness of alternative strategies for provision of HIV preexposure prophylaxis for people who inject drugs

HIV preexposure prophylaxis treatment patterns in a national health plan population

BACKGROUND

Medication nonadherence diminishes the benefits of preexposure prophylaxis (PrEP) for the 1.2 million Americans at risk for HIV exposure.

OBJECTIVE

To describe HIV PrEP treatment patterns among Medicare Advantage Prescription Drug (MAPD) plan and commercially insured beneficiaries.

METHODS

This retrospective cohort study identified patients aged 16 to 89 years with at least 1 dispensing of emtricitabine-tenofovir disoproxil fumarate from July 2012, through December 2020, or emtricitabine-tenofovir alafenamide from October 2019 through December 2020, and who were continuously enrolled at least 12 months prior to and following the earliest PrEP claim. Outcomes were HIV PrEP adherence measured by proportion of days covered (PDC) using 2 binary thresholds of 0.60 (4 doses/week) and 0.80 (5-6 doses/week) and duration of index treatment episode, total time on treatment, and total number of prescription fills.

RESULTS

The study cohort of 707 (292 MAPD plan, 415 commercial) was predominantly made up of male patients (90.0%) and resided in the South (78.9%) with a mean age of 46.2 years (MAPD plan: 54.5, commercial: 40.4). Both populations engaged in high-risk sexual behavior (All: 18.7%, MAPD plan: 16.8%, commercial: 20.0%) and experienced sexually transmitted infections (All: 3.3%, MAPD plan: 2.1%, commercial: 4.1%). The mean index treatment episode length was 297.0 days (MAPD plan: 283.6, commercial: 306.5). Total time on treatment was 477.3 days (MAPD plan: 450.7, commercial 496.0). At 3 months, 84.9% (MAPD plan: 83.6%, commercial: 85.8%) and at 12 months, 58.7% (MAPD plan: 57.2, commercial: 59.8) of patients achieved a PDC of at least 0.80. At 3 months, 100.0% (MAPD plan: 100.0%, commercial: 100.0%), and at 12 months, 74.3% (MAPD plan: 70.2%, commercial: 76.9%) of patients achieved a PDC of at least 0.60. The cohort had a mean of 16.4 fills of 30 days (MAPD plan: 16.4, commercial: 16.3) supply.

CONCLUSIONS

There is an opportunity for clinical programs to focus on improving longer-term PrEP adherence among individuals at risk for HIV exposure.

The Cost-Effectiveness of HIV/STI Prevention in High-Income Countries with Concentrated Epidemic Settings: A Scoping Review

The purpose of this scoping review is to establish the state of the art on economic evaluations in the field of HIV/STI prevention in high-income countries with concentrated epidemic settings and to assess what we know about the cost-effectiveness of different measures. We reviewed economic evaluations of HIV/STI prevention measures published in the Web of Science and Cost-Effectiveness Registry databases. We included a total of 157 studies focusing on structural, behavioural, and biomedical interventions, covering a variety of contexts, target populations and approaches. The majority of studies are based on mathematical modelling and demonstrate that the preventive measures under scrutiny are cost-effective. Interventions targeted at high-risk populations yield the most favourable results. The generalisability and transferability of the study results are limited due to the heterogeneity of the populations, settings and methods involved. Furthermore, the results depend heavily on modelling assumptions. Since evidence is unequally distributed, we discuss implications for future research.

Using Economic Evaluation to Inform Responses to the Opioid Epidemic in the United States: Challenges and Suggestions for Future Research

Background: Several aspects of the opioid epidemic and of public health care organization in the United States (US) make the conduct of economic evaluation and the design of policies to respond to this crisis particularly challenging. Objectives: This commentary offers suggestions for how economic evaluation may address and overcome four key features of the opioid epidemic: 1) its magnitude and geographical distribution, 2) its intersection with multiple epidemics, 3) its rapidly changing dynamics, 4) its multi-sectoral causes and consequences. Results: We first offer pragmatic suggestions to address the difficulties in delivering a coordinated response given the fragmented nature of health care in the US. In view of the broad suite of responses required to address opioid use disorder and its associated comorbidities, we highlight the need for economic evaluations which consider interventions throughout the continuum of care (i.e. primary, secondary and tertiary levels of prevention). We examine how the use of predictive modelling alongside economic evaluation might be adopted to address the rapidly evolving situation affecting distinct populations and geographic areas and encourage investments in epidemic preparedness. Finally, we propose methods to capture the interdependence of various sectors of government affected by the opioid crisis in economic evaluations to ensure optimal levels of investment towards a comprehensive response. Conclusions: The opioid epidemic in the US represents an unprecedented public health challenge, but sound epidemiological modelling and economic analysis can help to guide use of limited resources committed to addressing it in ways that can have greatest impact in limiting its adverse consequences.

Predicting the Effectiveness of Endemic Infectious Disease Control Interventions: The Impact of Mass Action versus Network Model Structure

BACKGROUND

Analyses of the effectiveness of infectious disease control interventions often rely on dynamic transmission models to simulate intervention effects. We aim to understand how the choice of network or compartmental model can influence estimates of intervention effectiveness in the short and long term for an endemic disease with susceptible and infected states in which infection, once contracted, is lifelong.

METHODS

We consider 4 disease models with different permutations of socially connected network versus unstructured contact (mass-action mixing) model and heterogeneous versus homogeneous disease risk. The models have susceptible and infected populations calibrated to the same long-term equilibrium disease prevalence. We consider a simple intervention with varying levels of coverage and efficacy that reduces transmission probabilities. We measure the rate of prevalence decline over the first 365 d after the intervention, long-term equilibrium prevalence, and long-term effective reproduction ratio at equilibrium.

RESULTS

Prevalence declined up to 10% faster in homogeneous risk models than heterogeneous risk models. When the disease was not eradicated, the long-term equilibrium disease prevalence was higher in mass-action mixing models than in network models by 40% or more. This difference in long-term equilibrium prevalence between network versus mass-action mixing models was greater than that of heterogeneous versus homogeneous risk models (less than 30%); network models tended to have higher effective reproduction ratios than mass-action mixing models for given combinations of intervention coverage and efficacy.

CONCLUSIONS

For interventions with high efficacy and coverage, mass-action mixing models could provide a sufficient estimate of effectiveness, whereas for interventions with low efficacy and coverage, or interventions in which outcomes are measured over short time horizons, predictions from network and mass-action models diverge, highlighting the importance of sensitivity analyses on model structure.

HIGHLIGHTS

• We calibrate 4 models-socially connected network versus unstructured contact (mass-action mixing) model and heterogeneous versus homogeneous disease risk-to 10% preintervention disease prevalence.• We measure the short- and long-term intervention effectiveness of all models using the rate of prevalence decline, long-term equilibrium disease prevalence, and effective reproduction ratio.• Generally, in the short term, prevalence declined faster in the homogeneous risk models than in the heterogeneous risk models.• Generally, in the long term, equilibrium disease prevalence was higher in the mass-action mixing models than in the network models, and the effective reproduction ratio was higher in network models than in the mass-action mixing models.

A review of network simulation models of hepatitis C virus and HIV among people who inject drugs

Network modelling is a valuable tool for simulating hepatitis C virus (HCV) and HIV transmission among people who inject drugs (PWID) and assessing the potential impact of treatment and harm-reduction interventions. In this paper, we review literature on network simulation models, highlighting key structural considerations and questions that network models are well suited to address. We describe five approaches (Erdös-Rényi, Stochastic Block, Watts-Strogatz, Barabási-Albert, and Exponential Random Graph Model) used to model partnership formation with emphasis on the strengths of each approach in simulating different features of real-world PWID networks. We also review two important structural considerations when designing or interpreting results from a network simulation study: (1) dynamic vs. static network and (2) injection only vs. both injection and sexual networks. Dynamic network simulations allow partnerships to evolve and disintegrate over time, capturing corresponding shifts in individual and population-level risk behaviour; however, their high level of complexity and reliance on difficult-to-observe data has driven others to develop static network models. Incorporating both sexual and injection partnerships increases model complexity and data demands, but more accurately represents HIV transmission between PWID and their sexual partners who may not also use drugs. Network models add the greatest value when used to investigate how leveraging network structure can maximize the effectiveness of health interventions and optimize investments. For example, network models have shown that features of a given network and epidemic influence whether the greatest community benefit would be achieved by allocating hepatitis C or HIV treatment randomly, versus to those with the most partners. They have also demonstrated the potential for syringe services and "buddy sharing" programs to reduce disease transmission.

Clinical Impact and Cost-effectiveness of Genotype Testing at Human Immunodeficiency Virus Diagnosis in the United States

BACKGROUND

US guidelines recommend genotype testing at human immunodeficiency virus (HIV) diagnosis ("baseline genotype") to detect transmitted drug resistance (TDR) to nonnucleoside reverse transcriptase inhibitors (NNRTIs), nucleoside reverse transcriptase inhibitors (NRTIs), and protease inhibitors. With integrase strand inhibitor (INSTI)-based regimens now recommended as first-line antiretroviral therapy (ART), the of baseline genotypes is uncertain.

METHODS

We used the Cost-effectiveness of Preventing AIDS Complications model to examine the clinical impact and cost-effectiveness of baseline genotype compared to no baseline genotype for people starting ART with dolutegravir (DTG) and an NRTI pair. For people with no TDR (83.8%), baseline genotype does not alter regimen selection. Among people with transmitted NRTI resistance (5.8%), baseline genotype guides NRTI selection and informs subsequent ART after adverse events (DTG AEs, 14%). Among people with transmitted NNRTI resistance (7.2%), baseline genotype influences care only for people with DTG AEs switching to NNRTI-based regimens. The 48-week virologic suppression varied (40%-92%) depending on TDR. Costs included $320/genotype and $2500-$3000/month for ART.

RESULTS

Compared to no baseline genotype, baseline genotype resulted in <1 additional undiscounted quality-adjusted life-day (QALD), cost an additional $500/person, and was not cost-effective (incremental cost-effectiveness ratio: $420 000/quality-adjusted life-year). In univariate sensitivity analysis, clinical benefits of baseline genotype never exceeded 5 QALDs for all newly diagnosed people with HIV. Baseline genotype was cost-effective at current TDR prevalence only under unlikely conditions, eg, DTG-based regimens achieving ≤50% suppression of transmitted NRTI resistance.

CONCLUSIONS

With INSTI-based first-line regimens in the United States, baseline genotype offers minimal clinical benefit and is not cost-effective.

Real-World Eligibility for HIV Pre-exposure Prophylaxis Among People Who Inject Drugs

Recent studies have highlighted the efficacy of and willingness to use pre-exposure prophylaxis (PrEP) to prevent HIV infection among people who inject drugs (PWID), however knowledge of real-world applicability is limited. We aimed to quantify the real-world eligibility for HIV-PrEP among HIV-negative PWID in Montreal, Canada (n = 718). Eligibility was calculated according to US Centers for Disease Control and Prevention (CDC) guidelines and compared to risk of HIV acquisition according to the assessing the risk of contracting HIV (ARCH-IDU) risk screening tool. Over one-third of participants (37%) were eligible for HIV PrEP, with 1/3 of these eligible due to sexual risk alone. Half of participants were considered high risk of HIV acquisition according to ARCH-IDU, but there was poor agreement between the two measures. Although a large proportion of PWID were eligible for HIV-PrEP, better tools that are context- and location-informed are needed to identify PWID at higher risk of HIV acquisition.

HIV and Substance Use Disorder: Role of the HIV Physician

The ongoing syndemic of substance use disorder and human immunodeficiency virus infection threatens progress made in preventing new infections and improving outcomes among those infected. To address this challenge effectively, human immunodeficiency virus physicians must take an increased role in the screening, diagnosis, and treatment of substance use disorders. Such treatment decreases human immunodeficiency virus risk behaviors and improves human immunodeficiency virus and substance use disorder-related outcomes. An effective response to this syndemic requires increased access to adjuvant interventions and a radical movement away from the current stigmatization and criminalization of those suffering from substance use disorders.

Dual Unsafe Injection and Sexual Behaviors for HIV Infection Among People Who Inject Drugs in Iran

We used two national surveys (2010: N = 1597; 2013: N = 1057) of people who inject drugs (PWID) in past-month to assess the prevalence and population size of PWID with either safe or unsafe injection and sex behaviors, overall and by HIV status. In 2013, only 27.0% (vs. 32.3% in 2010) had safe injection and sex, 24.6% (vs. 23.3% in 2010) had unsafe injection and sex, 26.4% (vs. 26.5% in 2010) had only unsafe injection, and 22.0% (vs. 18.0% in 2010) had unsafe sex only. Among HIV-positive PWID in 2013, only 22.1% (~ 2200 persons) had safe injection and sex, 14.2% (~ 1400 persons) had unsafe injection and sex, 53.1% (~ 5200 persons) had unsafe injection, and 10.6% had unsafe sex (~ 1100 persons). Among HIV-negative PWID in 2013, only 27.5% (~ 22,200 persons) had safe injection and sex, 25.9% (~ 20,900 PWID) had unsafe injection and sex, 23.2% (~ 18,700 persons) had unsafe injection, and 23.3% (~ 18,800 persons) had unsafe sex. HIV-positive and -negative PWID in Iran continue to be at risk of HIV acquisition or transmission which calls for targeted preventions services.

Review of Real-World Implementation Data on Emtricitabine-Tenofovir Disoproxil Fumarate as HIV Pre-exposure Prophylaxis in the United States

The antiretroviral combination of emtricitabine-tenofovir disoproxil fumarate (FTC/TDF) was approved by the U.S. Food and Drug Administration for use as pre-exposure prophylaxis (PrEP) in individuals at high risk for acquiring human immunodeficiency virus (HIV) in July 2012. Since then, Centers for Disease Control and Prevention guidelines for the use of PrEP have been published and implemented into clinical practice throughout the United States. A number of published open-label and PrEP demonstration projects have evaluated the real-world use of PrEP including analysis of the barriers to its use and addressing major concerns. Despite the approval of FTC/TDF for PrEP, its use for this indication relies on patient and provider acceptance, and its effectiveness requires patient adherence and retention in care during periods of high-risk behaviors. Concerns regarding the use of PrEP in healthy individuals persist and include medication adverse effects including renal dysfunction and bone mineral density loss; risk compensation leading to HIV infections, sexually transmitted infections, and unintended pregnancies; and the development of drug resistance in the event of seroconversion. The cost-effectiveness of PrEP continues to be assessed with the greatest cost-effectiveness remaining in those at highest risk of acquiring HIV. Additionally, cases of HIV acquisition in individuals who are adherent to PrEP highlight scenarios in which PrEP is not 100% effective including against the transmission of drug-resistant HIV strains. This review examines data on the implementation of PrEP outside the setting of clinical trials with the aim of providing clinicians with a summary of the current barriers and opportunities for PrEP use with a specific focus on the role of pharmacists in the optimization of PrEP implementation.

Perspectives on HIV pre-exposure prophylaxis (PrEP) utilization and related intervention needs among people who inject drugs

Background

Antiretroviral pre-exposure prophylaxis (PrEP) is clinically efficacious and recommended for HIV prevention among people who inject drugs (PWID), but uptake remains low and intervention needs are understudied. To inform the development of PrEP interventions for PWID, we conducted a qualitative study in the Northeastern USA, a region where recent clusters of new HIV infections have been attributed to injection drug use.

Methods

We conducted qualitative interviews with 33 HIV-uninfected PWID (hereafter, “participants”) and 12 clinical and social service providers (professional “key informants”) in Boston, MA, and Providence, RI, in 2017. Trained interviewers used semi-structured interviews to explore PrEP acceptability and perceived barriers to use. Thematic analysis of coded data identified multilevel barriers to PrEP use among PWID and related intervention strategies.

Results

Among PWID participants (n = 33, 55% male), interest in PrEP was high, but both participants and professional key informants (n = 12) described barriers to PrEP utilization that occurred at one or more socioecological levels. Individual-level barriers included low PrEP knowledge and limited HIV risk perception, concerns about PrEP side effects, and competing health priorities and needs due to drug use and dependence. Interpersonal-level barriers included negative experiences with healthcare providers and HIV-related stigma within social networks. Clinical barriers included poor infrastructure and capacity for PrEP delivery to PWID, and structural barriers related to homelessness, criminal justice system involvement, and lack of money or identification to get prescriptions. Participants and key informants provided some suggestions for strategies to address these multilevel barriers and better facilitate PrEP delivery to PWID.

Conclusions

In addition to some of the facilitators of PrEP use identified by participants and key informants, we drew on our key findings and behavioral change theory to propose additional intervention targets. In particular, to help address the multilevel barriers to PrEP uptake and adherence, we discuss ways that interventions could target information, self-regulation and self-efficacy, social support, and environmental change. PrEP is clinically efficacious and has been recommended for PWID; thus, development and testing of strategies to improve PrEP delivery to this high-risk and socially marginalized population are needed.