Background
Since the adoption of the Alma Ata Declaration in 1978 and most recently the Astana Declaration in 2018, primary care with community health workers (CHWs) has been considered a critical path to attain healthcare for all [
1,
2]. The specific definition of CHWs can differ, with the term encompassing a diverse group of “lay and educated, formal and informal, paid and unpaid health workers”. These CHWs provide services such as health education and can refer or support individuals and families seeking preventative or curative care. In recognition of the importance of community networks in health, the Global Strategy on Human Resources for Health: Workforce 2030 in 2016 was adopted by the 69th World Health Assembly and subsequently the World Health Organization (WHO) issued guidelines on health policy and system support to optimize CHW programs [
3,
4]. These guidelines specifically offered a set of recommendations on CHWs selection, training, management and supervision, career advancement, community embeddedness, and health system support.
Despite substantial evidence on CHWs and their positive impact on communities [
5,
6], there remain key knowledge gaps. In particular, the WHO guidelines cited knowledge gaps across six key themes: (1) intervention activities; (2) recruitment/selection; (3) training; (4) compensation/remuneration; (5) supervision; and (6) sustainable integration into the health system [
4]. Moreover, studies have decried the lack of evidence on how to integrate and support CHWs within health systems and the “rights and needs of CHWs” [
5]. Another review posited that efficacy assessments of CHW projects were carried out under ideal circumstances, leading to a need for more evidence under “real world” conditions [
7].
Prior to the COVID-19 pandemic, tuberculosis (TB) was registered as the deadliest infectious disease caused by a single pathogen, resulting in 10 million cases and 1.4 million deaths in 2019 [
8]. Meanwhile, the United Nations has made the elimination of TB one of its Sustainable Development Goals [
9] and the WHO End TB Strategy aims for a 90% reduction in TB incidence rate by 2035 [
10]. These global ambitions acknowledge the importance of community involvement in the fight to end TB, particularly through strengthening the community health workforce.
The contribution of CHWs to TB care and prevention have been well documented [
11,
12]. Specifically, CHWs have enabled the task-shifting of a variety of TB program responsibilities to optimize capacity utilization of the public health system. These decentralized tasks include active case finding [
13]; sputum collection and transport, slide fixing and other laboratory support [
14]; and treatment support, such as community-based directly observed treatment (DOT) and psychosocial support [
15]. As a result, the deployment of CHWs in TB programs has been linked to improved patient treatment outcomes [
16], increased case notification [
17], and decreased treatment loss to follow-up (LTFU) [
18]. Nevertheless, despite the substantial evidence on the activities and responsibilities that CHWs can assume, the understanding of best practices for engagement of CHWs and the operationalization of CHW models for TB care and prevention remains limited.
Stop TB Partnership established TB REACH in 2010 to foster innovative approaches and technologies in TB care and prevention and catalyze their scale-up. Over the course of eight waves, the TB REACH mechanism [
19] has supported hundreds of projects utilizing numerous approaches to active case finding (ACF), many of which heeded the global call for greater involvement of CHWs. As such, TB REACH represents one of the world’s largest sources of funding and repository of information for interventions employing CHWs using a standardized monitoring and evaluation (M&E) framework [
20].
Discussion
Our retrospective data collection and analysis of 50 survey responses from TB REACH project implementers provided information on a broad range of CHW engagement models for TB interventions carried out globally. This information contributes to filling the knowledge gaps in the existing literature on the roles of CHWs and elucidates variables facilitating project success. The results of our study found that CHW interventions overall had a large positive impact on yielding incremental TB notifications in intervention areas. The CHW model factors more likely to influence project outcomes are the training method and setting, supervisory models, and integration into the existing health system.
Regarding training, we found capacity building through hands-on or practical applications in a community setting was associated with more successful case finding. This was concordant with a systematic review that showed that outcomes are improved when training is combined with other capacity building measures, and an additional review that found that training for diagnostic tests should be addressed through hands-on practice and consistent feedback from experienced health care workers or supervisors [
23,
24]. Training completed in the community is also highlighted by Gilroy and Winch, in which a commonly cited problem in CHW studies is “training that is too classroom-based with little practical hands-on experience” [
25]. While our survey found that the classroom was the most common training setting, some projects reported training in both the classroom and the community. The higher impact groups had a larger proportion of projects that incorporated community-based training. This reinforces that training CHWs on practical skills in the community which they will eventually serve can contribute to better prepared health workers.
Our multivariate regression found that the two projects utilizing e-learning methods during pre-service training yielded higher additionality. Although e-learning is not yet commonly used for CHW training, the current COVID-19 pandemic may catalyze a potentially positive paradigm shift in capacity building. A study in sub-Saharan Africa found that the blended approach combining e-learning with classroom training for CHWs improved standardization of training content and retention to course materials due to the ability to revisit online course materials [
26]. The study also showed a total training cost savings of 42% from reduced travel, personnel, and classroom costs. Thus, e-learning proves to be a promising mode of training. Further studies and projects should explore the potential of integrating mobile or remote health technologies in their training models, especially given the new realities of travel and meetings in many countries.
The majority of projects in our survey had CHW performance issues addressed by a direct supervisor without the need of upper management involvement. Supervisors provided direct feedback to CHWs an average of 13 times per quarter (3 months), leading us to believe that the regularity of feedback is unlikely to influence project outcomes. However, a previous study on CHW models have also noted that regular supervision can be demotivating as some CHWs perceive their supervision to be linked to their poor performance [
27]. Conversely, more supportive supervision by formal health workers can provide CHWs with a sense of legitimacy and increased work motivation [
28]. As the evidence base remains ambiguous, more research is needed on the most optimal roles of supervisors should play in order to best support CHWs.
The effective integration of CHWs into the existing health systems is a well-documented enabler of project success [
5,
6] as it enhances sustainability and fosters collaboration between lay and formal healthcare providers. CHWs have also vociferously noted an enhanced credibility and clarity of their own roles with a greater level of integration [
5,
29]. Our study results were concordant with these findings. Projects that had CHWs continue the same roles and responsibilities after the close of the project tended to produce a greater additionality impact on TB notifications. This may suggest that projects offering the prospect of long-term engagement through ties with the public health system and other health networks had a positive impact on CHW performance. Another hypothesis is that CHWs originally employed by the project decided to continue their roles because the project was successful. Pallas et al. posit that integrating CHW programs into the agendas of ministries of health, non-governmental organizations, and international donors can create more impactful CHW models that are sustainable even during times of political unrest or a reduction of external donor funding [
30]. Thus, it is beneficial to embed CHW models within primary health care systems for them to be both sustainable and impactful.
More projects that we surveyed compensated their CHWs through a fixed component (salary or stipend) than through a variable component. A study on three large CHW programs in India has found an unmet demand for salaried positions and service conditions for CHWs and that the volunteer status can hinder CHWs from receiving job benefits and fair salaries. This study specified that performance-based incentives lack financial security in large-scale CHW programs such as the Accredited Social Health Activist (ASHA) [
31]. Moreover, our survey also evinced that more projects in the high-impact group tended to provide their CHWs with additional benefits beyond monetary compensation, including the provision of health insurance and priority access to disease testing. This highlights that additional benefits contribute to higher CHW job satisfaction and performance, which in turn may translate into to higher outputs and larger impact of the project. The importance of fair and commensurate compensation and the potentially positive impact on TB case notifications has been noted in other studies as well [
32].
A key strength of this study was the unique data source. As one of the largest funding mechanisms for TB, our access to the GMS allowed us to use a robust dataset on the characteristics and outcomes of projects with CHW engagement models across many different countries. Access to this database also facilitated the recruitment of project implementers. Our survey was developed to closely align with the WHO guidelines on health policy and system support to optimize CHW programs, allowing us to obtain details on how concrete implementers’ experiences support or discount the recommendations of these guidelines, and which of the recommendations to prioritize in the context of leveraging CHWs for TB ACF. As such, while our study results are largely concordant with WHO recommendations, concrete experiences from TB REACH projects utilizing CHWs identified factors such as community-based training, rigorous support and supervision, and intentional integration into the existing health care system that may be prioritized to increase the likelihood of incremental notification impact and successful implementation of CHW models for TB.
Our study was limited by the attempt to associate project and CHW characteristics with TB REACH’s primary outcome metric, trend-adjusted changes in TB case notifications (additionality). While this can offer a less biased measure of performance, we had to exclude a number of projects for which the additionality assessment was confounded by external factors (see Additional file
1: Table A3: Factors Affecting Additionality). Additionality is also only one metric by which active TB case finding interventions can be assessed, and it is possible that projects that yielded a low additionality could have had a high impact on other evaluation metrics. We also experienced a low overall response rate (41%) to our survey. Several implementers noted that responses to specific survey questions may not be accurate due to difficulties recalling details from projects implemented many years ago.
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