To date, the majority of literature on HIV and syndemics has focused on HIV and other infectious diseases such as tuberculosis (TB) and hepatitis [1,2]. HIV is now considered a chronic disease and, with an ageing population of people living with HIV (PLHIV), the huge syndemic burden of noncommunicable diseases (NCDs) has become more visible . With this convergence of epidemics, our goal should be to provide a person-centred, holistic approach to the medical needs of the individual.
Over the last two decades, the scale-up of antiretroviral therapy (ART) has been heralded as the first successful chronic disease treatment programme in resource-limited settings . The 90–90–90 targets – of having 90% of PLHIV knowing their HIV status, 90% of those people being on ART and 90% of those on ART being virally suppressed – have been universally adopted; as of mid-2019, more than 20 million PLHIV were on ART, which is an achievement of 79–62–53 in the cascade of care adopting all PLHIV as the denominator . Variants mirroring these 90–90–90 targets have been set for TB  and hepatitis C  and could easily be applied to other chronic diseases, but have not yet been set for NCDs. A recent analysis from 44 countries, including over 1 million participants of whom 192 441 (17.5%) had hypertension, demonstrated that the cascade for hypertension in low and middle-income countries was 39–29–10  – emphasizing the huge progress of HIV programmes in comparison to the response to a much more long-standing public health challenge.
In recent years, HIV programmes have transitioned from providing a ‘one-size fits all’ approach to ART delivery, recognizing the diversity of client needs in the era of ‘treat all’ . One such approach is differentiated service delivery (DSD), defined as a client-centred approach that simplifies and adapts HIV services across the cascade, in ways that both serve the needs of PLHIV and reduces unnecessary burdens on the health system . The majority of countries with substantial numbers of PLHIV in sub-Saharan Africa have adopted a DSD approach to HIV, adapting the ‘building blocks’ of who (service provider), when (service frequency), where (service location) and what (service package) to the needs of a person living with HIV. The principles of DSD were not developed to be exclusive to HIV, but with the vision that DSD could support chronic disease management across the cascade of care. Furthermore, the DSD concepts have also been adopted in the context of managing other comorbidities such as TB preventive treatment [11–14]. However, to date, little has been documented on how the principles of DSD may be applied to PLHIV who have other comorbidities.
THE SYNDEMICS OF HIV, HYPERTENSION AND DIABETES
This review focuses on the syndemics of hypertension and/or diabetes with HIV for the following reasons: First, there is a growing body of evidence that countries with the highest prevalence of HIV have an overlapping and substantial disease burden of diabetes and hypertension (Table 1). Second, like HIV, diabetes and hypertension both require lifelong treatment interventions. Further, it is well established that HIV itself increases the risk of cardiovascular disease [15,16] as do some antiretrovirals, making the treatment of these chronic disease syndemics even more pertinent.
Global deaths in 2018 because of HIV, hypertension and diabetes were 770 000 , 9.4 million , 4.2 million , respectively. A metaanalysis demonstrated no significant differences between type II diabetes prevalence in PLHIV compared with uninfected individuals [risk ratio (RR) = 1.61, 95% confidence interval (CI): 0.62–4.21] . The prevalence of hypertension amongst PLHIV over 50 years of age ranged from 31.9% in sub-Saharan Africa to 50.2% in North America. In the three rural regions of Kenya and Uganda that were part of the Sustainable East Africa Research in Community Health (SEARCH) trial, the prevalence of hypertension was 21.3% at baseline [23▪]. In Kenya, modelling work demonstrated that 62% of adults living with HIV have at least one other NCD compared with 51% of other adults [24,25]. In Zimbabwe, it is projected that, by the year 2035, adults living with HIV will be twice as likely to have at least one NCD compared with HIV-negative adults .
STARTING WITH INTEGRATION
Literature on the delivery of NCD and HIV treatment has largely focused on the role of ‘integration’. Definition of this term is not consistent with some settings providing care truly as a one-stop service, whereas others provide care on the same day through different providers [27,28] or in different locations. Integration of NCD and HIV services has also not been taken to scale. The reasons and barriers to this will be addressed later.
HIV services can be used as a platform for broader NCD integration. For example, in Kenya, NCD screening with HIV testing had important effects on the continuum of NCD care. Immediately after the first year of screening campaigns, treatment in the intervention communities increased from 10 to 47% for diabetes and from 8 to 27% for hypertension [29▪].
In rural Malawi, a chronic disease care clinic utilized a robust HIV programme to provide NCD screening and treatment. The clinic provided longitudinal care for clients with a range of chronic conditions supporting a single visit to address all comorbidities. The clinic organization aimed to maximize efficiency, given the severe human resource challenges, and replicate strong HIV outcomes for clients with other chronic conditions .
BEYOND HIV: LEVERAGING DIFFERENTIATED SERVICE DELIVERY FOR HIV TO INCLUDE THOSE WITH HYPERTENSION OR DIABETES
There are notable and emerging examples of where HIV and NCD services are provided in a truly client-centred and differentiated way.
In urban Kenya, a primary care clinic providing HIV and NCD care established facility-based groups called medication adherence clubs, or MACs, to provide care and treatment to people living with diabetes, hypertension, HIV or any combination of these conditions. Loss to follow-up from the MACs was 3.5% . Clients found the MACs acceptable and the members appreciated the comprehensive health education and the opportunity to discuss a range of chronic conditions. Such an approach may in fact be a route to successfully reducing the stigma felt when attending specific HIV clinics .
In South Africa, all guidance on DSD is not limited to HIV but is part of the National Adherence Guidelines for HIV, TB and NCDs . In the country, there are three endorsed DSD models – facility pick-up points at health facilities (often referred to in other countries as a ‘fast-track’ model), adherence clubs (both facility and community-based) and external pick-up points (where medications are collected outside of health facilities). All of these DSD models apply to HIV, diabetes and hypertension and provide for two-monthly treatment refills and semiannual or annual clinical consultations at the client's health facility. Where clients have more than one chronic condition, treatment refill visits and clinical consultation visits are integrated. Nationally, as of 7th February 2020, more than 273 000 clients with HIV and hypertension or diabetes collected treatment for both conditions through these models. Additional 498 000 clients with hypertension or diabetes collected their chronic treatment refills through these models .
In the SEARCH trial in rural Uganda and Kenya, intervention communities received patient-centred care for HIV, diabetes and hypertension compared with the care in accordance with national guidance. The DSD approach for HIV was also utilized for treatment of hypertension and diabetes including ‘3-month visit intervals, flexible hours, reduced wait time at clinics, and a welcoming staff’. After three years, among those with hypertension, a higher proportion of those in the intervention group had achieved control of their hypertension compared with those in the standard of care (47 versus 37%). This improvement was also observed among those with both HIV and hypertension; 72% of those in the intervention and 59% of those in the control group had achieved control of their hypertension after three years [23▪].
TAKING THE DIFFERENTIATED SERVICE DELIVERY APPROACH TO HYPERTENSION AND DIABETES
Faced with the realities of scaling up treatment for all 37 million people with HIV, health systems could not continue providing care with a ‘business as usual’ approach. The number of people in need of being diagnosed and treated for diabetes and hypertension call for a similar and maybe even more radical adaptation of services to reach those in need and ensure long-term continuity of care. Adaptation of DSD for HIV to offering DSD for NCD clients who are HIV negative is the natural progression.
In Nigeria, the CLUBMEDS study is underway to assess the delivery of hypertension care through community-based clubs of 10–15 people under the leadership of a role model client. The club aims to encourage and facilitate adherence, carry out blood pressure monitoring and deliver medication. The CLUBMEDS study includes a formative (preimplementation) qualitative evaluation, a pilot study and a process (postimplementation) qualitative evaluation and aims to evaluate the feasibility and impact of adherence clubs to improve hypertension control in Nigeria [35▪].
ADDRESSING KEY BARRIERS AND SUPPORTING ENABLERS TO PROVIDE NONCOMMUNICABLE DISEASE CARE IN DIFFERENTIATED SERVICE DELIVERY MODELS
In addition to HIV programmes being attributed as being the first, successful chronic disease management programmes in resource limited settings, numerous articles have also been written suggesting how NCD programmes could and should learn lessons from the public health approach taken in HIV programming incorporating such principles as decentralization and task sharing [36,37].
So why are we not doing better to differentiate and integrate care for other chronic conditions? Essential to enabling DSD for HIV has been the leadership of the World Health Organization (WHO) who has provided programmes with simplified clinical guidance developed with a public health approach, while understanding the need for differentiation [4,38]. Treatment regimens have been designed using the principles of optimization [including fixed-dose combinations (FDCs) facilitating minimum formulations for procurement, minimal pill burden and low toxicity] along with harmonization (selecting a regimen that can be used across populations, e.g. general population and those with TB or pregnant and lactating women). To date, such a public health approach to hypertension and diabetes has not been taken; with algorithms requiring multiple titration steps and often imposing a large pill burden for clients. Opportunities do exist to change this and to move toward a simplified algorithm including use of FDCs to both optimize and harmonize guidance as outlined in the WHO Global HEARTS package . However, one preferred algorithm is not identified at present [40▪,41▪].
Clear global fast-track targets agreed upon among UN agencies, ministries of health and across implementing partners that are measurable at a clinic level are required, alongside strong engagement of the recipients of care in the design, planning and delivery of services. The HIV response has benefited greatly from the engagement of PLHIV in all aspects of services as well as the activism from communities and PLHIV to galvanize the implementation of the global targets.
Critically, funding of diagnostics and monitoring tests and a continuous supply of essential medication – for hypertension and diabetes – has been dependant on ministries of health or the private healthcare sector rather than donors or large international procurers. As such, even when products, such as antihypertensive drugs and metformin for the treatment of type II diabetes, are inexpensive, they may not be supplied in resource-limited settings. Wider availability of these essential products is a massive challenge , with, for example, the proportion of communities with four antihypertensive drug classes available being as low as 13% in low income countries . Without addressing these key barriers, providing differentiated service delivery for NCDs remains theoretical.
Finally, the lack of investment in client held records and cohort monitoring of diabetes and hypertension means the forecasting of future needs both for workforce and drug and diagnostic procurement remains extremely difficult. Lack of forecasting also makes it more difficult for countries to negotiate lower, volume-based pricing. Lack of investment in client records also means that quality of care is also not being assessed in terms of retention and control (i.e. measuring longer term blood pressure for hypertension and hemoglobin A1c (HbA1c) for diabetes to assess programme success). Huge sums have been invested in electronic medical records for HIV and adaptation of such tools could be made to support management of other chronic diseases.
There have been numerous articles written to describe how lessons learned from HIV programmes can benefit NCD management [36,37]. Using the nomenclature of DSD may be a way of galvanizing ART and NCD programmes to work together to put these lessons into practice for both the HIV, hypertension and diabetes syndemics and for NCD care among those who are HIV negative. To do this, HIV and NCD departments at international and national levels must agree on the use of the principles of DSD and work together to implement and document on-the-ground experiences.
Donors also need to consider the impact of not addressing these syndemics both in terms of morbidity and mortality of HIV cohorts and the impact on other programmes, such as incidence and outcomes of TB programmes. Implementing partners should consider these syndemics across the cascade of care and enable the growing cohort of ageing PLHIV to continue a healthier life through more comprehensive and holistic care for all their chronic conditions. Further implementation science demonstrating impact on retention and clinical outcomes is needed and a commitment to provide essential medicines and diagnostic tests needs to be at the forefront of any such plan.
Thank you to Nelli Bazarova for comments on earlier versions of the manuscript and support with referencing.
Financial support and sponsorship
The IAS receives funding from the Bill & Melinda Gates Foundation (Investment number: INV002610) to support work on differentiated service delivery. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Conflicts of interest
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