The number of people living with HIV (PLWH) who have started life-saving antiretroviral therapy (ART) has markedly increased in low- and middle-income countries (LMICs) [1]. This impressive development, however, has led to overcrowding in health care facilities, longer waiting times during visits, and reduced time for counseling and clinical care of newly enrolled patients. In most public sector clinics in LMICs, it has also restricted the workforce’s capacity to provide ongoing adherence support and monitor patients who do not remain engaged in care (treatment engagement) to ensure optimal ART-related benefits on patient health and community HIV prevention [2]. Further, in July 2014, UNAIDS called for a global scale-up of treatment as prevention and efforts to meet the following “90-90-90” targets by 2030: (1) 90 % of all people living with HIV should know their HIV status (90 % diagnosed); (2) 90 % of all people diagnosed with HIV infection should receive ART (90 % on treatment); and (3) 90 % of all people receiving ART should achieve viral suppression [3]. This ambitious target for 73 % of all PLWH with documented undetectable viral load is expected to be associated with a significant decrease in HIV-related morbidity and mortality, lowest risk of sexual transmission, and decrease in HIV incidence at population level as well as supported by the latest World Health Organization (WHO) guidelines recommending treating all PLWH irrespective of immune status [4•]. It implies that an additional 21 million people are in need for treatment as of 2015 and underscores the importance of strengthening health systems’ capacity to meet the growing health needs within communities [4•].

Emerging data from both resource rich and limited settings have demonstrated that a substantial reduction in patient retention in clinical care occurs between each stage of the HIV treatment continuum from diagnosis and linkage to care, assessment of ART readiness to acceptability, receipt of initial ART, adherence and long-term retention in care, and treatment success as reflected by virologic suppression [5, 6, 7•, 8]. A systematic review reported that retention of PLWH on ART at 36 months in LMICs averages only 65 to 70 % [9•]. This proportion is markedly lower in patients who present to hospitals with advanced HIV. Success along the HIV treatment cascade is even worse in key populations, namely, pregnant women, children and adolescents, sex workers, people who inject drugs, and men who have sex with men, and they are at high risk of acquiring as well as transmitting HIV to others, thus experiencing poor clinical and public health outcomes [10–15]. Against this background, it is critical to determine how effective interventions are at every level of the treatment cascade to prevent new infections and promote health outcomes to achieve the goal of an AIDS-free generation [7•].

In LMICs, selected approaches to reducing loss at every stage of the HIV treatment cascade include decentralization of services and task-shifting aspects of care to nurses and to nonclinical staff, including lay counselors who may be patients themselves. These approaches have been found to be feasible, effective, and results in good clinical outcomes [16–18]. Task shifting is now recommended and being scaled up in LMICs [16–19]. Such facility-based strategies, however, are reaching their limits as increasing numbers of patients initiate ART. Recently, suggestions have been made to expand accessible and flexible community-based ART service delivery, differentiating the needs of clinically ill patients starting ART or in need of significant adherence counseling from the needs of clinically stable patients with documented optimal ART adherence. This transition from facility- to community-based treatment has been identified as an important strategies for maintaining retention in HIV care and improving ART adherence, and viral suppression, but without reducing quality of care [16].

Community-based programs to promote retention in HIV care and/or ART adherence are now increasingly being recognized as an important and sustainable approach that could contribute significantly toward the UNAIDS 90-90-90 target and ultimately an AIDS-free generation [20–27, 28•, 29–32]. Such approaches are also seen as an essential mechanism of service delivery, including dispensing of ART, and a means of decongesting traditional health services, rather than being purely an adherence adjunct. Furthermore, such interventions are likely to be cost-effective from a societal perspective by offering a shift of certain tasks from overburdened and high-cost health care settings directly into communities and para-professional staff, reducing also transportation costs for patients [33, 34].

We conducted a systematic review and meta-analysis to compare the effect of community-based ART delivery on treatment engagement, ART adherence, virologic suppression, and all-cause mortality among PLWH in LMICs against results obtained from patients treated in traditional health care facilities.

This review found no statistical difference in optimal ART adherence, virologic suppression, all-cause mortality, and loss to follow-up between those participants assigned to community-based ART and facility-based ART, when the analysis was restricted to RCTs. In the pooled analysis from both RCTs and cohort studies, however, we documented that participants assigned to community-based ART had significantly higher rates of retention in care than those in facility-based ART at the end of the follow-up period.

The above results corroborate the fact that providing patient support and education programs at the community level are equal and certainly not inferior compared to facility-based ones and may in fact be superior when it comes to selected outcomes such as retention in HIV care. Of note, our analysis may be underpowered to show superiority on selected outcomes such as virologic outcomes and all-cause mortality. Of note, ascertainment of selected outcomes such as all-cause mortality is better in the community than in the facility-based settings due to the fact that mortality in facility-based studies may be under-ascertained, which will make mortality in the community looks higher [68]. At the same time, silent health facility-based patient transfer (patients are being seen at other clinics, but the clinic-of-origin staff think that they are disengaged in care) will likely be under-captured, thus making health facility-based retention in care worse [68].

In building decentralized ART delivery, adherence, and retention in care support, community-based ART programs encourage patient autonomy, build social networks, and minimize the structural barriers, such as cost of transport to the clinic, which in turn appear to result in better outcomes [69]. Such community-based interventions are likely to have more impact since they tend to involve trained community health workers, peers, volunteers, or patient’s own social network members (e.g., family and friends) who assist with ART adherence counseling and support. In addition, there is evidence that they may provide material, instrumental, and emotional support, as well as promote other healthy behaviors, such as decreased alcohol and drug use, leading to better health outcomes—including survival [14, 24, 29, 32]. Furthermore, enhancing certain aspects of the patient–supporter relationships—such as trust, supporter availability, communication, reciprocity of support, and medication assistance—in a manner consistent with patients’ expectations may help to optimize the relationship and its positive impact on patient health [14, 24, 70].

Our study complements the findings of a previous review that assessed the effect of home-based interventions on viral outcomes in sub-Saharan Africa; this review found that there were insufficient data to be conclusive [70]. Another recent review summarized the evidence supporting different models of community participation for ART care or community-based ART in resource-limited settings; these community ART programs made treatment readily accessible and affordable [71]. In Uganda and Kenya, community health workers or volunteers delivered ART at home [41, 62], while in Tete, Mozambique, a demonstration project of people living with HIV/AIDS used self-formed community-based ART groups to deliver ART in the community [19]. Also, in South Africa, Médecins Sans Frontières piloted ART adherence clubs with promising results [27]. These clubs may provide some adherence counseling and peer support, as well as enable a “fast track” refill mechanisms. Patients are placed in groups of approximately six patients, and one member of the group (rotating each month) is permitted to obtain refills for all of the patients in his or her group. These approaches decrease the patient burden on health facilities, reduce transportation costs and waiting times for patients, and help overcome structural barriers. They also reduce treatment fatigue and loss to follow-up, increase disclosure and treatment education, and may help patients develop necessary social ties. While supportive of community-based interventions, these evaluations used observational study designs with possibility of selection and observational bias as well as confounding, and most of them did not have a valid comparator and could not be included in our meta-analysis.

We also investigated as secondary outcomes two potential concerns related to community-based ART adherence and retention programs, including reported stigma and low quality of care which could result in an increased all-cause mortality. In terms of stigma, an RCT reported that only 3 % of patients refused to participate in the home-based ART program due to stigma [25]. Furthermore, it has even been suggested that involvement of community-health care workers in HIV care reduced stigma [72] and being part of peer groups has been found to decrease the perception of social stigma [73].

Our results have important clinical and public health implications in the context of reaching the 2030 UNAIDS 90-90-90 targets toward an AIDS-free generation. While this systematic review and meta-analysis did not examine the first step of the HIV treatment cascade, HIV diagnosis, it did examine the next two. Importantly, community-based interventions aim to conveniently deliver a package of essential ART care functions that extend beyond the clinic into the community such as ART refills, monitoring of treatment adherence and outcomes, and detection of sick patients linked to rapid referral to care. This, in turn, frees up capacity within the clinic-based medical workforce to be able to focus on complicated tasks such as clinical care for sick patients, training and supervision of lay health care workers, and management of health care services. Of note, task shifting is somewhat limited in selected LMICs (e.g., Brazil, Argentina, Mexico, and Puerto Rico), because a physician always needs to be present, at the very least to sign off every single prescription. Second, community-based ART delivery and adherence monitoring and support models for clinically stable patients with documented virologic suppression hold the potential of enabling countries to build sustainable, cost-effective, and equitable HIV care for populations in countries with a scarce health care workforce. Indeed, a cost-effectiveness study by Marseille and colleagues concluded that a home-based ART program in rural Africa may be more cost-effective than most previous estimates for facility-based ART programs [74]. Only three cohort studies involved children [46, 49•, 52•]. The outcomes reported by these studies were virologic suppression, mortality, and loss to follow-up, and all of these were not different from what was obtainable in the adult population. These studies were conducted in South Africa and Uganda.

Surprisingly, we found only two eligible studies to inform cost or cost-effectiveness outcomes. Clearly, more research using economic outcomes is needed. Available data suggest that community-based ART services even if they are equivalent to, but not superior to clinic-based programs, may be more cost-effective from a societal perspective because personnel, operational, and utility costs are likely to be lower, and transportation costs for patients will also be lower; these facts, added to the increased effectiveness in terms of retention, are likely to make community-based ART much more cost-effective and sustainable in the long run. In addition, as mentioned, community-based approaches also make use of community health workers, and an overall community health model that will enable a transformation of the health system from the current vertical siloes to a more integrated approach where community-based HIV care may be further combined with care for other chronic conditions, including non-communicable diseases such as cardiovascular and metabolic diseases which are becoming more prevalent in LMICs as these countries experience the epidemiological and demographic transitions.

Our study has several strengths. We performed a comprehensive search of several databases and sources to identify eligible cohorts and RCTs with the latter providing the highest quality of evidence. Two authors independently evaluated each study for inclusion and data extraction. Regarding limitations, inclusion of cohort study designs may bias the overall estimate of effects due to unmeasured confounding not adjusted for in multivariate analyses. Indeed, the fact that we are observing a difference between RCTs and observational studies for the ART adherence outcome may reflect that in many if not all of these community-based interventions, the patients who end up in the intervention, if it is not randomized, are likely to be quite a bit different—selected somehow—for stability even if not measured. However, in the context of implementation science, observational studies often provide strong signals of important direction of effect. Also, as mentioned earlier, facility-based treatment engagement may have been underestimated since such outcome does not account for silent transfers, and which therefore may not completely capture retention in care [68]. Finally, with only 11 RCTs, we may be underpowered to show superiority of either type interventions.

In summary, community- versus facility-based models of ART delivery resulted in at least comparable outcomes for clinically stable HIV-infected patients on treatment in LMICs and are likely to be cost-effective. As ART rollout expands in LMICs, health systems need to continually adjust to accommodate further expansion. Community-based ART delivery for stable patients hold the promise of enabling countries to build sustainable, cost- effective, and equitable HIV care for populations in settings with a scarce health workforce. Further research with well-powered studies may be needed to further explore effectiveness and cost-effectiveness of such community-based ART programs, particularly in under-represented patient groups such as HIV-infected children, adolescents, and pregnant women to sustain optimal outcomes.