Hypertension control in integrated HIV and chronic disease clinics in Uganda in the SEARCH study

There is an increasing non-communicable disease (NCD) burden globally, with an estimated one billion people living with hypertension and about 9.4 million related deaths annually [1]. Global trends are mirrored in sub-Saharan Africa (SSA) [2‐4] where hypertension has become a major public health problem [5]. Population surveys of prevalence reveal a large burden of undiagnosed and untreated hypertension across SSA [6‐8], and suggest that even among individuals in care, hypertension is successfully controlled in less than a quarter [7].

HIV is more prevalent in SSA than anywhere else in the world [9] and the region is facing a dual HIV-NCD epidemic. The expansion of life-saving antiretroviral therapy (ART) has decreased HIV related morbidity and mortality [10, 11], leading to an aging population living with HIV who are more susceptible to NCDs such as hypertension [12, 13]. As concern about the management of NCDs among people living with HIV (PLHIV) grows, the infrastructure that has been built for the provision of ART and other care services must be leveraged and adapted to respond to the growing burden of NCDs among both PLHIV and HIV-uninfected populations.

In this setting, lessons learned from the HIV chronic disease treatment model can be applied to the management of other chronic diseases such as hypertension. Integrated care systems are more convenient for patients, decrease stigma associated with healthcare, and could be more efficient for government and non-governmental funders. However, evidence-based care models for scaling up integrated HIV/NCD care are lacking [14]. In particular, little is known about the health systems factors that might influence HTN control when leveraging HIV chronic care systems to provide care for persons with hypertension, with or without co-occurring HIV infection. In the HIV chronic care model, systems factors such as clinic waiting times, inconvenient clinic hours, and unfriendly attitudes from staff, and frequency of schedule visits are associated with patient engagement in care and clinical outcomes [15]. In addition, drug stock outs for cardiovascular medications are frequent in SSA [16] and visit frequency, which is often determined by drug supply, is associated with clinical outcomes in the HIV chronic care model [17, 18].

In the Sustainable East Africa Research in Community Health (SEARCH) study (NCT01864603), population level screening of HIV and HTN was performed at community health campaigns, and individuals with either or both diseases were linked to integrated care at local health facilities [19, 20]. The integrated care model addressed many of the known structural barriers to engagement in care through flexible clinic hours with decreased wait times, patient-centered care, and welcoming attitudes. In this study we set out to: 1) characterize the patient population and HTN control over time among of adult residents who linked to HTN care using an integrated chronic care delivery model that offered treatment for both HTN and HIV disease and 2) evaluate predictors of HTN control over time.

To work towards hypertension control in SSA we need to optimize health systems for chronic care delivery. In this study of hypertension outcomes among patients referred to integrated chronic disease care after population-wide screening we found that blood pressure control increased more than threefold from 15% at baseline. Nevertheless, blood pressure was controlled in slightly less than half (46%) of all follow-up visits. We identified a modifiable systems factor, more frequent clinic visits precipitated by drug stock outs, as one of the barriers to hypertension control.

Achieving hypertension control at a population level starts with screening and linkage to clinical care. After population-based screening, 45% of patients with prevalent hypertension were linked to NCD care. This number may underestimate true linkage, however, as individuals who were normotensive on presentation to clinic and not enrolled in NCD care were not counted, however they still fall short of ideal. Linkage to NCD care following screening remains a challenge across the region – a recent meta-analysis on hypertension in SSA estimated only 14–22% patients were in care following hypertension diagnosis [5]. Our population-based, multi-disease approach may have increased linkage by increasing health-seeking behavior in the communities; however, additional efforts targeted towards engagement in NCD care are needed.

Our population who sought care were approximately two thirds female, while population-based screening demonstrated higher prevalence among men [26]. Our clinic population that is enriched for women is similar to other reported clinic populations [7] likely reflects the health care seeking behavior of women in a health care system created primarily for women and children. Only 15% were on blood pressure lowering medications at baseline, reflecting the large burden of undiagnosed disease in this part of the world. Over 1/3 had stage 2 hypertension at the time of screening suggesting this undiagnosed burden is severe.

We found that hypertension control was achieved at 46% of follow-up visits. This is similar to findings of a multisite population population-based screening across 6 sites in South Africa, Kenya, Ghana, Burkina Faso, Sierra Leone where HTN control in 47% of those in treatment [8] and slightly higher than 37% hypertension control among those on blood pressure lowering medication in a population based study in Malawi [6]. However, we measure hypertension control over time rather than a single point estimate, which provides a more complete picture of hypertension control in the clinic community.

Similar to findings that improved HIV outcomes are associated with extended intervals between scheduled clinic visits [17, 18], we found that patients whose scheduled visit intervals were more frequent than clinical guidelines had worse BP control. Medication stock levels contributed to more frequent scheduled visits (i.e. < 12 weeks despite hypertension control) at 20% of visits. This finding provides critical information for targeting reduced patient visits per clinical guidelines for efficient chronic care for stable controlled patients and ensuring the clinic infrastructure, including drug supply, can support less frequent visits. More reliable drug supply chains for NCDs will be crucial to this effort [27].

Patients with dual diagnoses of HIV and hypertension were more likely to achieve normal blood pressure over time than those patients receiving care for hypertension only. Hypertension care was integrated into HIV clinic visits preventing redundant visits and HIV-infected patients also received extensive counseling about daily medication adherence and retention support which may have led to increased adherence among HIV-infected patients. These tools can be adapted to support engagement in care for other chronic disease to improve outcomes.

Other integration initiatives can inform the successful integration of HIV and hypertension care. Integrated TB and HIV care leads to decreased both HIV and TB-associated morbidity and mortality [28]. Co-location of services is associated with fewer delays in starting ART and greater uptake of ART among HIV/TB co-infected patients [29‐31] versus referral to a separate facility for TB or HIV care. Similarly, integration of family planning and HIV counseling and testing increases uptake of both among post-partum women when compared to stand-alone service delivery [32]. We provided integrated HIV and hypertension care under the same roof enabling “one-stop” shopping for patients. As hypertension and chronic care for other NCDs is integrated with HIV chronic care across SSA, co-located services, a well-trained workforce, and clinic infrastructure will likely be crucial to successful treatment of both.

Our data only captures individuals who are in care for hypertension treatment; outcomes following transfer or loss to care were not assessed. Nonetheless, understanding blood pressure control among those individuals receiving treatment is important to improving outcomes within the health care system. More detailed analysis of the effect of class of antihypertensive treatment would provide additional insight into mechanisms of blood pressure control, however the focus of this current analysis is on individual clinical factors and health systems factors that contribute to hypertension control. Additionally, blood pressure measured at clinic represents a single point in time and we thus have an incomplete picture of overall hypertension control in this population. Clinic-based blood pressure measurements potentially misclassify individuals with white coat hypertension (where an individual presents as hypertensive in clinic but is normotensive out of clinic) or masked hypertension (where an individual presents as normotensive in clinic but has elevated blood pressure on ambulatory or home BP monitoring) and the prevalence in SSA is estimated to be 15 and 11% respectively [33]. However, these misclassifications would likely bias our results towards the null. Finally, adherence to blood pressure lowering medications was not evaluated in this analysis, however adherence to medication is likely reflected in the blood pressure measurements performed in clinic. Future work will probe adherence and challenges to adherence among those with poor hypertension control.

Our study registered successes in population level screening for HIV and hypertension, in linkage to integrated chronic disease care and hypertension control for both HIV positive and HIV negative patients with hypertension. Our study contributes evidence to realize effective responses for HIV care and emerging NCDs, including hypertension, in SSA. However, there is need to continue to optimize the integrated care model to achieve ideal patient outcomes.