Assessing effectiveness and cost-effectiveness of concurrency reduction for HIV prevention

Making Smarter Decisions Faster: Systems Engineering to Improve the Global Public Health Response to HIV

PURPOSE OF REVIEW

This review offers an operational definition of systems engineering (SE) as applied to public health, reviews applications of SE in the field of HIV, and identifies opportunities and challenges of broader application of SE in global health.

RECENT FINDINGS

SE involves the deliberate sequencing of three steps: diagnosing a problem, evaluating options using modeling or optimization, and providing actionable recommendations. SE includes diverse tools (from process improvement to mathematical modeling) applied to decisions at various levels (from local staffing decisions to planning national-level roll-out of new interventions). Contextual factors are crucial to effective decision-making, but there are gaps in understanding global decision-making processes. Integrating SE into pre-service training and translating SE tools to be more accessible could increase utilization of SE approaches in global health. SE is a promising, but under-recognized approach to improve public health response to HIV globally.

Cost-effectiveness of HIV Prevention Interventions in Sub-Saharan Africa: A Systematic Review

BACKGROUND

Sub-Saharan Africa carries the highest HIV burden globally. It is important to understand how interventions cost-effectively fit within guidelines and implementation plans, especially in low- and middle-income settings. We reviewed the evidence from economic evaluations of HIV prevention interventions in sub-Saharan Africa to help inform the allocation of limited resources.

METHODS

We searched PubMed, Web of Science, Econ-Lit, Embase, and African Index Medicus. We included studies published between January 2009 and December 2018 reporting cost-effectiveness estimates of HIV prevention interventions. We extracted health outcomes and cost-effectiveness ratios (CERs) and evaluated study quality using the CHEERS checklist.

FINDINGS

60 studies met the full inclusion criteria. Prevention of mother-to-child transmission interventions had the lowest median CERs ($1144/HIV infection averted and $191/DALY averted), while pre-exposure prophylaxis interventions had the highest ($13,267/HIA and $799/DALY averted). Structural interventions (partner notification, cash transfer programs) have similar CERs ($3576/HIA and $392/DALY averted) to male circumcision ($2965/HIA) and were more favourable to treatment-as-prevention interventions ($7903/HIA and $890/DALY averted). Most interventions showed increased cost-effectiveness when prioritizing specific target groups based on age and risk.

INTERPRETATION

The presented cost-effectiveness information can aid policy makers and other stakeholders as they develop guidelines and programming for HIV prevention plans in resource-constrained settings.

Nonidentifiability in Model Calibration and Implications for Medical Decision Making

BACKGROUND

Calibration is the process of estimating parameters of a mathematical model by matching model outputs to calibration targets. In the presence of nonidentifiability, multiple parameter sets solve the calibration problem, which may have important implications for decision making. We evaluate the implications of nonidentifiability on the optimal strategy and provide methods to check for nonidentifiability.

METHODS

We illustrate nonidentifiability by calibrating a 3-state Markov model of cancer relative survival (RS). We performed 2 different calibration exercises: 1) only including RS as a calibration target and 2) adding the ratio between the 2 nondeath states over time as an additional target. We used the Nelder-Mead (NM) algorithm to identify parameter sets that best matched the calibration targets. We used collinearity and likelihood profile analyses to check for nonidentifiability. We then estimated the benefit of a hypothetical treatment in terms of life expectancy gains using different, but equally good-fitting, parameter sets. We also applied collinearity analysis to a realistic model of the natural history of colorectal cancer.

RESULTS

When only RS is used as the calibration target, 2 different parameter sets yield similar maximum likelihood values. The high collinearity index and the bimodal likelihood profile on both parameters demonstrated the presence of nonidentifiability. These different, equally good-fitting parameter sets produce different estimates of the treatment effectiveness (0.67 v. 0.31 years), which could influence the optimal decision. By incorporating the additional target, the model becomes identifiable with a collinearity index of 3.5 and a unimodal likelihood profile.

CONCLUSIONS

In the presence of nonidentifiability, equally likely parameter estimates might yield different conclusions. Checking for the existence of nonidentifiability and its implications should be incorporated into standard model calibration procedures.

Humanitarian medical supply chain in disaster response

Purpose

Following a large-scale disaster, medical assistance is a critical component of the emergency response. The paper aims to discuss this issue.

Design/methodology/approach

Academic and practitioner literature is used to develop a framework studying the effectiveness of the humanitarian medical supply chain (HMSC). The framework is validated by using the findings of interviews conducted with experts and the case study of a serious humanitarian medical crisis (Ebola outbreak in 2014).

Findings

The factors affecting the effectiveness of the HMSC are identified.

Research limitations/implications

To get an expert opinion on the major logistical challenges of the medical assistance in emergencies only 11 interviews with practitioners were conducted.

Originality/value

While the existing academic literature discusses the distribution of various supplies needed by the affected population, limited research focuses specifically on studying the HMSC aspect of the response. This paper closes this gap by describing the HMSC in the case of disaster response, and identifying the factors affecting its effectiveness, especially focusing on the factors that are unique to the medical aspect of the humanitarian supply chain.

Concurrency and Other Sexual Risk Behaviors Among Black Young Adults in a Southeastern City

Black Americans continue to have higher rates of HIV disease than other races/ethnicities. Conventional individual-level risk behaviors do not fully account for these racial/ethnic disparities. Sexual concurrency may help explain them. Respondent-driven sampling (RDS) was used to enroll 508 sexually active 18- to 30-year-old Black men and women in Durham, North Carolina in a cross-sectional survey on HIV-related topics. Consistent condom use was low for all participants, especially with steady partners. Concurrent partnerships in the past 6 months were relatively common for both men (38%) and women (25%). In general, men involved in concurrent relationships engaged in more risk behaviors than other men (e.g., inconsistent condom use and alcohol and drug use). A majority of concurrent partnerships involved steady partners. HIV-prevention programs should address the risks of concurrency and factors that discourage condom use, especially with steady partners with whom condom use is particularly low.

Dynamic Transmission Economic Evaluation of Infectious Disease Interventions in Low- and Middle-Income Countries: A Systematic Literature Review

Economic evaluation using dynamic transmission models is important for capturing the indirect effects of infectious disease interventions. We examine the use of these methods in low- and middle-income countries, where infectious diseases constitute a major burden. This review is comprised of two parts: (1) a summary of dynamic transmission economic evaluations across all disease areas published between 2011 and mid-2014 and (2) an in-depth review of mosquito-borne disease studies focusing on health economic methods and reporting. Studies were identified through a systematic search of the MEDLINE database and supplemented by reference list screening. Fifty-seven studies were eligible for inclusion in the all-disease review. The most common subject disease was HIV/AIDS, followed by malaria. A diverse range of modelling methods, outcome metrics and sensitivity analyses were used, indicating little standardisation. Seventeen studies were included in the mosquito-borne disease review. With notable exceptions, most studies did not employ economic evaluation methods beyond calculating a cost-effectiveness ratio or net benefit. Many did not adhere to health care economic evaluations reporting guidelines, particularly with respect to full model reporting and uncertainty analysis. We present a summary of the state-of-the-art and offer recommendations for improved implementation and reporting of health economic methods in this crossover discipline.

Measuring the Potential Impact of Combination HIV Prevention in Sub-Saharan Africa

A public health approach to combination HIV prevention is advocated to contain the epidemic in sub-Saharan Africa. We explore the implications of universal access to treatment along with HIV education scale-up in the region. We develop an HIV transmission model to investigate the impacts of universal access to treatment, as well as an analytical framework to estimate the effects of HIV education scale-up on the epidemic. We calibrate the model with data from South Africa and simulate the impacts of universal access to treatment along with HIV education scale-up on prevalence, incidence, and HIV-related deaths over a course of 15 years. Our results show that the impact of combined interventions is significantly larger than the summation of individual intervention impacts (super-additive property). The combined strategy of universal access to treatment and HIV education scale-up decreases the incidence rate by 74% over the course of 15 years, whereas universal access to treatment and HIV education scale up will separately decrease that by 43% and 8%, respectively. Combination HIV prevention could be notably effective in transforming HIV epidemic to a low-level endemicity. Our results suggest that in designing effective combination prevention in sub-Saharan Africa, priorities should be given to achieving universal access to treatment as quickly as possible and improving compliance to condom use.

Creating impact with operations research in health: making room for practice in academia

Operations research (OR)-based analyses have the potential to improve decision making for many important, real-world health care problems. However, junior scholars often avoid working on practical applications in health because promotion and tenure processes tend to value theoretical studies more highly than applied studies. This paper discusses the author's experiences in using OR to inform and influence decisions in health and provides a blueprint for junior researchers who wish to find success by taking a similar path. This involves selecting good problems to study, forming productive collaborations with domain experts, developing appropriate models, identifying the most salient results from an analysis, and effectively disseminating findings to decision makers. The paper then suggests how journals, funding agencies, and senior academics can encourage such work by taking a broader and more informed view of the potential role and contributions of OR to solving health care problems. Making room in academia for the application of OR in health follows in the tradition begun by the founders of operations research: to work on important real-world problems where operations research can contribute to better decision making.

Reducing Concurrent Sexual Partnerships Among Blacks in the Rural Southeastern United States: Development of Narrative Messages for a Radio Campaign

In the United States, heterosexual transmission of HIV infection is dramatically higher among Blacks than among Whites. Overlapping (concurrent) sexual partnerships promote HIV transmission. The authors describe their process for developing a radio campaign (Escape the Web) to raise awareness among 18-34-year-old Black adults of the effect of concurrency on HIV transmission in the rural South. Radio is a powerful channel for the delivery of narrative-style health messages. Through six focus groups (n = 51) and 42 intercept interviews, the authors explored attitudes toward concurrency and solicited feedback on sample messages. Men were advised to (a) end concurrent partnerships and not to begin new ones; (b) use condoms consistently with all partners; and (c) tell others about the risks of concurrency and benefits of ending concurrent partnerships. The narrative portrayed risky behaviors that trigger initiation of casual partnerships. Women were advised to (a) end partnerships in which they are not their partner's only partner; (b) use condoms consistently with all partners; and (c) tell others about the risks of concurrency and benefits of ending concurrent partnerships. Messages for all advised better modeling for children.

What can mathematical models tell us about the relationship between circular migrations and HIV transmission dynamics?

Circular migrations are the periodic movement of individuals between multiple locations, observed in parts of sub-Saharan Africa. Relationships between circular migrations and HIV are complex, entailing interactions between migration frequency, partnership structure, and exposure to acute HIV infection. Mathematical modeling is a useful tool for understanding these interactions. Two modeling classes have dominated the HIV epidemiology and policy literature for the last decade: one a form of compartmental models, the other network models. We construct models from each class, using ordinary differential equations and exponential random graph models, respectively. Our analysis suggests that projected HIV prevalence is highly sensitive to the choice of modeling framework. Assuming initial equal HIV prevalence across locations, compartmental models show no association between migration frequency and HIV prevalence or incidence, while network models show that migrations at frequencies shorter than the acute HIV period predict greater HIV incidence and prevalence compared to longer migration periods. These differences are statistically significant when network models are extended to incorporate a requirement for migrant men's multiple partnerships to occur in different locations. In settings with circular migrations, commonly-used forms of compartmental models appear to miss key components of HIV epidemiology stemming from interactions of relational and viral dynamics.

A systematic review of the effectiveness and cost-effectiveness of peer-based interventions to maintain and improve offender health in prison settings

Background

Offender health is deemed a priority issue by the Department of Health. Peer support is an established feature of prison life in England and Wales; however, more needs to be known about the effectiveness of peer-based interventions to maintain and improve health in prison settings.

Objectives

The study aimed to synthesise the evidence on peer-based interventions in prison settings by carrying out a systematic review and holding an expert symposium. Review questions were (1) what are the effects of peer-based interventions on prisoner health and the determinants of prisoner health?, (2) what are the positive and negative impacts on health services within prison settings of delivering peer-based interventions?, (3) how do the effects of peer-based approaches compare with those of professionally led approaches? and (4) what are the costs and cost-effectiveness of peer-based interventions in prison settings?

Data sources

For the systematic review, 20 electronic databases including MEDLINE, PsycINFO, the Cumulative Index to Nursing and Allied Health Literature and EMBASE were searched from 1985. Grey literature and relevant websites were also searched. To supplement the review findings 58 delegates, representing a variety of organisations, attended an expert symposium, which provided contextual information.

Review methods

Two reviewers independently selected studies using the following inclusion criteria: population – prisoners resident in prisons and young offender institutions; intervention – peer-based interventions; comparators: review questions 3 and 4 compared peer-led and professionally led approaches; outcomes – prisoner health or determinants of health, organisational/process outcomes or views of prison populations; study design: quantitative, qualitative and mixed-methods evaluations. Two reviewers extracted data and assessed validity using piloted electronic forms and validity assessment criteria based on published checklists. Results from quantitative studies were combined using narrative summary and meta-analysis when appropriate; results from qualitative studies were combined using thematic synthesis.

Results

A total of 15,320 potentially relevant papers were identified of which 57 studies were included in the effectiveness review and one study was included in the cost-effectiveness review; most were of poor methodological quality. A typology of peer-based interventions was developed. Evidence suggested that peer education interventions are effective at reducing risky behaviours and that peer support services provide an acceptable source of help within the prison environment and have a positive effect on recipients; the strongest evidence came from the Listener scheme. Consistent evidence from many predominantly qualitative studies suggested that being a peer deliverer was associated with positive effects across all intervention types. There was limited evidence about recruitment of peer deliverers. Recurring themes were the importance of prison managerial and staff support for schemes to operate successfully, and risk management. There was little evidence on the cost-effectiveness of peer-based interventions. An economic model, developed from the results of the effectiveness review, although based on data of variable quality and a number of assumptions, showed the cost-effectiveness of peer-led over professionally led education in prison for the prevention of human immunodeficiency virus (HIV) infection.

Limitations

The 58 included studies were, on the whole, of poor methodological quality.

Conclusions

There is consistent evidence from a large number of studies that being a peer worker is associated with positive health. Peer support services can also provide an acceptable source of help within the prison environment and can have a positive effect on recipients. This was confirmed by expert evidence. Research into cost-effectiveness is sparse but a limited HIV-specific economic model, although based on a number of assumptions and evidence of variable quality, showed that peer interventions were cost-effective compared with professionally led interventions. Well-designed intervention studies are needed to provide robust evidence including assessing outcomes for the target population, economic analysis of cost-effectiveness and impacts on prison health services. More research is needed to examine issues of reach, utilisation and acceptability from the perspective of recipients and those who choose not to receive peer support.

Study registration

This study was registered as PROSPERO CRD42012002349.

Funding

The National Institute for Health Research Health Services and Delivery Research programme.

From coitus to concurrency: sexual partnership characteristics and risk behaviors of 15-19 year old men recruited from urban venues in Tanzania

Understanding the uptake and patterns of sexual partnerships of adolescent males reveals their risky behaviors that could persist into adulthood. Using venue-based sampling, we surveyed 671 male youth ages 15-19 from an urban Tanzanian neighborhood about their sexual partnerships during the past 6 months. The proportion of males who had ever had sex increased with age (21 % at age 15; 70 % at age 17; 94 % at age 19), as did the proportion who engaged in concurrency (5 % at age 15; 28 % at age 17; 44 % at age 19). Attendance at ≥2 social venues per day and meeting a sexual partner at a venue was associated with concurrency. Concurrency was associated with alcohol consumption before sex among 18-19 year olds and with not being in school among 15-17 year olds. We find that concurrency becomes normative over male adolescence. Venue-based sampling may reach youth vulnerable to developing risky sexual partnership patterns.

Sex role segregation and mixing among men who have sex with men: implications for biomedical HIV prevention interventions

OBJECTIVE

Men who have sex with men (MSM) practice role segregation - insertive or receptive only sex positions instead of a versatile role - in several international settings where candidate biomedical HIV prevention interventions (e.g., circumcision, anal microbicide) will be tested. The effects of these position-specific interventions on HIV incidence are modeled.

MATERIALS AND METHODS

We developed a deterministic compartmental model to predict HIV incidence among Indian MSM using data from 2003-2010. The model's sex mixing matrix was derived from network data of Indian MSM (n=4604). Our model captures changing distribution of sex roles over time. We modeled microbicide and circumcision efficacy on trials with heterosexuals.

RESULTS

Increasing numbers of versatile MSM resulted in little change in HIV incidence over 20 years. Anal microbicides and circumcision would decrease the HIV prevalence at 10 years from 15.6% to 12.9% and 12.7% respectively. Anal microbicides would provide similar protection to circumcision at the population level despite lower modeled efficacy (54% and 60% risk reduction, respectively). Combination of the interventions were additive: in 5 years, the reduction in HIV prevalence of the combination (-3.2%) is almost the sum of their individual reductions in HIV prevalence (-1.8% and -1.7%).

CONCLUSIONS

MSM sex role segregation and mixing, unlike changes in the sex role distribution, may be important for evaluating HIV prevention interventions in international settings. Synergies between some position-specific prevention interventions such as circumcision and anal microbicides warrant further study.

Measuring and modelling concurrency

This article explores three critical topics discussed in the recent debate over concurrency (overlapping sexual partnerships): measurement of the prevalence of concurrency, mathematical modelling of concurrency and HIV epidemic dynamics, and measuring the correlation between HIV and concurrency. The focus of the article is the concurrency hypothesis - the proposition that presumed high prevalence of concurrency explains sub-Saharan Africa's exceptionally high HIV prevalence. Recent surveys using improved questionnaire design show reported concurrency ranging from 0.8% to 7.6% in the region. Even after adjusting for plausible levels of reporting errors, appropriately parameterized sexual network models of HIV epidemics do not generate sustainable epidemic trajectories (avoid epidemic extinction) at levels of concurrency found in recent surveys in sub-Saharan Africa. Efforts to support the concurrency hypothesis with a statistical correlation between HIV incidence and concurrency prevalence are not yet successful. Two decades of efforts to find evidence in support of the concurrency hypothesis have failed to build a convincing case.

Inferring model parameters in network-based disease simulation

Many models of infectious disease ignore the underlying contact structure through which the disease spreads. However, in order to evaluate the efficacy of certain disease control interventions, it may be important to include this network structure. We present a network modeling framework of the spread of disease and a methodology for inferring important model parameters, such as those governing network structure and network dynamics, from readily available data sources. This is a general and flexible framework with wide applicability to modeling the spread of disease through sexual or close contact networks. To illustrate, we apply this modeling framework to evaluate HIV control programs in sub-Saharan Africa, including programs aimed at concurrent partnership reduction, reductions in risky sexual behavior, and scale up of HIV treatment.

Cost-effective control of chronic viral diseases: finding the optimal level of screening and contact tracing

Chronic viral diseases such as human immunodeficiency virus (HIV) and hepatitis B virus (HBV) afflict millions of people worldwide. A key public health challenge in managing such diseases is identifying infected, asymptomatic individuals so that they can receive antiviral treatment. Such treatment can benefit both the treated individual (by improving quality and length of life) and the population as a whole (through reduced transmission). We develop a compartmental model of a chronic, treatable infectious disease and use it to evaluate the cost and effectiveness of different levels of screening and contact tracing. We show that: (1) the optimal strategy is to get infected individuals into treatment at the maximal rate until the incremental health benefits balance the incremental cost of controlling the disease; (2) as one reduces the disease prevalence by moving people into treatment (which decreases the chance that they will infect others), one should increase the level of contact tracing to compensate for the decreased effectiveness of screening; (3) as the disease becomes less prevalent, it is optimal to spend more per case identified; and (4) the relative mix of screening and contact tracing at any level of disease prevalence is such that the marginal efficiency of contact tracing (cost per infected person found) equals that of screening if possible (e.g., when capacity limitations are not binding). We also show how to determine the cost-effective equilibrium level of disease prevalence (among untreated individuals), and we develop an approximation of the path of the optimal prevalence over time. Using this, one can obtain a close approximation of the optimal solution without having to solve an optimal control problem. We apply our methods to an example of hepatitis B virus.