The cascade of hypertension care in Cambodia: evidence from a cross-sectional population-based survey

Hypertension (HTN) is a leading cause of cardiovascular diseases (CVD) and deaths globally [1]. An estimated 1.28 billion adults aged 30–79 years live with HTN globally, with two-thirds living in low- and middle-income countries [2]. It is a rising problem in many low- and middle-income countries [3], including Cambodia. The prevalence of HTN among adults aged 40–69 years in Cambodia was 23.5% in 2016 [4].

In response to this high prevalence, Cambodia has been re-organizing its health system to play an essential role in ensuring the effective management of HTN. In 2007, the government included management of HTN as basic care in the minimum package of activities by enabling primary care level facilities, such as health centers (HCs), to treat mild HTN and refer severe and complicated cases to district referral hospitals (RHs) [5]. Through support from the government and donor organizations, additional and innovative interventions for HTN and other non-communicable diseases, especially diabetes, have been introduced at different levels in the public health system and community in selected provinces. These include the following interventions: (1) the establishment of Non-Communicable Disease (NCD) clinics at the RHs, (2) the introduction of the World Health Organization Package of Essential Non-Communicable Disease Interventions (WHO PEN) program in HCs, and (3) the expansion and integration of the community-based MoPoTsyo’s Peer Educator Network.

NCD clinics have been established by the Ministry of Health (MoH) to provide hospital-based care for NCDs at RHs since 2007 with the aim of providing care for people with type 2 diabetes (T2D) and/or HTN through screening, diagnosis, treatment, and health education. Currently, 31 clinics are functional in selected operational districts (ODs) in 17 provinces. With regard to HTN, the NCD clinics offer consultation and treatment services to people living in the area.

The WHO PEN program has been implemented as health center-based care since 2015. This intervention aims to complement the function of the NCD clinics through screening suspected T2D and HTN cases. With regard to HTN, WHO PEN provides counseling, screening, and treatment for mild cases of HTN, and follow-up treatment for referred HTN patients at the HC level. The WHO PEN program has encouraged CVD risk screening, including blood pressure (BP) measurement, for adults aged 40 years and older. It is supported by the WHO and other non-government organizations [6]. As of February 2021, it covered 121 HCs. The activities mentioned in the WHO PEN comply with the new Minimum Package of Activities of the MoH, which allowed the treatment for mild HTN at HCs and referred severe and complicated HTN to RHs [7]. Mild or non-complicated cases of hypertension are allowed to be treated at the HC by mostly secondary nurses and sometimes midwives (with 3 years of pre-service training), and exceptionally by medical doctors in HCs where they are present.

The MoPoTsyo Peer Educator Network, established and supported by a local non-government organization, provides community-based care and support for people with T2D and HTN. In the network, peer educators who are diabetic patients themselves, after being trained by the organization, provide regular follow-up checks and counseling to other patients registered in the network and assist them in getting access to medical services at RHs. With regard to HTN, peer educator networks also organize (1) community-based screening, (2) self-management support, (3) medication supply under a revolving drug fund, and (4) service operation through public facilities. MoPoTsyo is active in 20 districts in 8 provinces [8, 9].

While the interventions above take place at public health facilities, it must be noted that a significant proportion of the population does not use public healthcare [10]. Private facilities have been the primary choice of care for Cambodians when they get sick or injured; evidently, more than 70% of all healthcare visits took place at private healthcare providers in 2016 [11]. Furthermore, a majority (59%) of people with chronic diseases were diagnosed and treated in private facilities [12].

A multitude of interventions exists at both public and private facilities to diagnose and treat HTN in Cambodia, including the aforementioned innovative interventions in the public sector. However, little is known about the outcomes of these interventions. Studying the outcomes of a chronic condition such as HTN is complex since effective care for HTN requires a continuum of care (prevalence, screening, diagnosis, treatment, follow-up treatment, and control of HTN). An adverse health outcome at the end can be caused by a health system weakness at any of these steps. Therefore, applying a Cascade of Care (CoC) approach is critical to assess these outcomes. A CoC is a model to outline the sequential stage of long-term care (prevalence, screening, diagnosis, treatment, follow-up treatment, and control) required to achieve a desirable outcome. From a healthcare system perspective, a CoC model is a very useful tool for understanding where the health system has failed, to quantify losses and identify the characteristics of people lost in each stage of the care continuum.

A first but not comprehensive attempt to assess a cascade of HTN care was made through the national STEPS survey in 2016. This survey showed that, among respondents aged 18–69 years, 12.9% had their BP measured and were diagnosed with HTN. Of these, 32.7% were then taking prescribed medication, while only 16.1% of those on medication had their BP controlled [4]. The 2016 STEPS survey, however, produced the CoC for the population aged 18–69 years, rendering these results less useful to assess outcomes of the health system interventions that targeted the at-risk population. The healthcare guidelines on screening and treatment defined those aged 40 years or older as the ‘at-risk population’. In addition, the 2016 STEPS survey also did not collect additional information on the healthcare use related to HTN from one of the above-cited health system interventions. These limitations render additional up-to-date research on the at-risk population, their healthcare use, and resulting health outcome.

To better understand the effects of the above-cited health system interventions, it is also relevant to look at patient-related factors that influence the outcomes of HTN care. Socio-demographic and economic characteristics, for instance, might impact access to screening, diagnosis, or treatment, and consequently health outcomes in different ways. The influence of such factors on different steps in the cascade is not well documented and might be context-specific. Previous studies using the CoC approach have been previously published in the USA [13, 14], Brazil [15], and other Asian countries including India, China, Malaysia, and Laos [16‐20], stressing the need for context-specific research in Cambodia.

This study aims to build an extended cascade of HTN care in Cambodia and explore the demographic characteristics explaining the ‘drop-out’ in the CoC. The extended cascade is composed of six bars: prevalence (i), screening (ii), diagnosis (iii), treatment in the last 12 months (iv), treatment in the last three months (v), and being under control (vi). The analysis will inform policymakers about the health system’s performance and differences in risk characteristics across the continuum of HTN care. Additionally, it will provide insights into the reasons for inequities in access and outcomes.

Our results indicate that people drop out across all steps of the cascade, with the most substantial losses in the steps from having HTN to screening, from screening to diagnosis, and from treatment in the last three months to having one’s HTN under control. Around 55% of those diagnosed with HTN have a good continuation of their care process, from in treatment to a regular follow-up. Only one-third of the study participants with HTN reached the last bar of the cascade of care—well-controlled. This shows that incorporating HTN as basic care combined with the multitude of additional interventions has not sufficiently addressed this public health problem in Cambodia.

Overall, the produced cascade of HTN care is comparable; however, there are some marked differences with those produced by similar studies in the region. Compared to the study on adults aged over 40 years in Indonesia, the prevalence of HTN in Cambodia was lower (47.8% in Indonesia vs. 35.1% in Cambodia), whereas the proportions of people aware of their diagnosis (29.4% vs. 63.7%), under-treatment (25% vs. 54.3%), and control (9.0% vs. 35.8%) were higher [27]. When compared to the results from a previous study in central Vietnam in 2015 among the population aged 40–69 years, our study had a lower prevalence (44.8% in Vietnam vs. 35.1% in Cambodia), a comparable proportion of awareness of diagnosis (67.3% vs. 63.7%), a higher proportion in treatment (33.2% vs. 54.2%), and a higher proportion in control (12.2% vs. 35.8%) [26]. Another study in the rural community people in Thailand on the population aged 35–60 years produced a similar pattern only in the proportion of awareness and treatment, but higher result in control [28]. Possible explanations for the lower prevalence but a higher number of people achieving control in Cambodia compared to the studies in central Vietnam and Indonesia, and the similar results compared to rural Thailand might be explained by the population characteristics and the resources and priority-setting in each setting, for instance, the coverage of HTN care, the performance in health service delivery, and population lifestyle.

The produced CoC in this study provides crucial evidence to the Cambodian government to steer their strategies for HTN control. The CoC approach clearly necessitates that the National Strategy needs to recognize the importance of ensuring continuous service use along the cascade of HTN care in order to durably improve HTN care in Cambodia. The CoC methodology applied in this study could be a valuable tool to monitor progress towards reaching this continuum of care.

The three largest drops demonstrated by our study provide insight on the gaps in the health system in HTN care; policymakers must take action regarding these to prevent a failure in the health system. First, a substantial loss of people living with HTN who reported not receiving screening suggests the importance of making screening programs more widely available at the primary healthcare level by increasing coverage and capacity of HCs in providing NCD service delivery. Second, the biggest drop from screening to diagnosis sheds light on the importance of on-time detection. This detection is vital since early detection can minimize the long-term impact on the health system and economic development [29, 30].

The last biggest loss was from people who received follow-up treatment in the last three months to people who had their HTN under control, this implies inadequate treatment. Despite having been on anti-hypertensive treatment, a large proportion of people could not achieve optimal BP control. This problem requires a combination of quality treatment and comprehensive intervention of lifestyle modification.

The findings of our study on the profiles of those dropping out from one bar of the cascade to another also demonstrated that, compared to the poorest households, people from the poor to richest households were more likely to receive screening, but only people from rich households remained in treatment and those from medium wealth households achieved good control of HTN. Socio-economic status impacted the utilization of health services as mentioned in many published studies [31‐33]. In our study, most of the rich population reported using care from private facilities while at the same time it was demonstrated that those visiting private facilities were less likely to have their HTN controlled. This results in the fact that, even though people from the richest households were more likely to be in care, they were not more likely to have their HTN under control compared to people from the poorest households who were in treatment. This reflects the inefficiency of care and treatment which restrains users from achieving the optimal goal of care. The role of private healthcare is undeniable for HTN care when a majority of Cambodians have been using private care. WHO reports on the relative efficiency of public and private service delivery showed inconclusive evidence due to lack of data and absence of evidence-based study on efficiency [34]. To ensure the most efficient HTN health service delivery, a mixed strategy is needed from the government by introducing measurement of efficiency to identify key causes and constraints to improve the performance of HTN healthcare nationwide. Additionally, introducing innovative financial schemes to cover HTN service uses can help keep patients in the continuum of care without the risk of catastrophic health expenditure regardless of the type of health facility they use.

The inequities in the continuum of HTN care between men vs. women, population under or equal to 49 years vs. over 50 years, people living with HTN less than five years vs. more than five years, and agricultural vs. non-agricultural workers demonstrate that the health system is not reaching all people equally and/or is not producing equal outcomes across these different groups. This result is not affected by the large proportion of female participants in our survey. Evidently, the prevalence of HTN is not so different between males and females (34.6% vs. 35.5%) and the results of the 2017 and 2019 Cambodia Socio-Economic Surveys found that women sought care at the health facility more than men in all areas in Cambodia [35, 36]. Men were found to have a lower control rate and delay in seeking help when they became ill [37, 38]. It is clear that an innovative health system approach is required to tackle these issues. In light of the limited resources for health in Cambodia, one potential pathway to produce more equitable access to essential HTN care is the double strategy of building additional community-based care (to improve access) while improving the quality of facility-based care (to improve health outcomes). Taking into account the required continuum of care for chronic conditions such as HTN, community care could be a valuable extension of the professional healthcare team, by providing social support in medication adherence, self-management support through home visits, referral for facility-based care, reporting, and follow-up. This approach has been successfully used to improve management and reduce the gap of inequities of HTN care in Nepal [39] and Pakistan [40].

Our study found a high prevalence of HTN (35.2%) among adults aged 40 years and older while only one-third of those with HTN achieved a complete continuum of care and good health outcome. Our findings demonstrated that the CoC approach can be a useful tool to assess the effectiveness of HTN care and associated health outcome and should be used as a monitoring tool to assess the national strategy and potentially advise investments in healthcare for chronic conditions as it provides insights into where (as well as which) people are along the continuum of HTN care. Priority (for interventions and investments in expanding HTN care) should be given to males, those aged 40–49 years, and poorer population groups. This will not only allow achieving the best outcome but also reduce health inequities, thereby contributing to achieving Universal Health Coverage. Among people receiving HTN care in the last three months, those accessing care in private facilities were less likely to achieve well-controlled BP. These results demonstrated that a double strategy of quality health facility-based and community-based interventions is needed at different levels to increase screening uptake, awareness of their diagnosis, continuous treatment, and good control of their HTN. To minimize the inequitable access to healthcare, the interventions should use the data produced by the CoC approach to focus on the major drops and those likely to drop in the cascade.

With political commitment towards Universal Health Coverage, this study took the first step by providing a comprehensive overview of the performance of current HTN care along with all steps of the continuum of care and an in-depth understanding of the characteristics of the people at risk of dropping out at each step of this continuum. This is indeed essential to see how far Cambodia is in terms of HTN care to reach Universal Health Coverage. Future research should be conducted to closely look at the healthcare performance for both public and private care nationwide.