Improving community-based care for diabetes mellitus and hypertension in Lesotho

The burden of Non-communicable diseases (NCD) is increasing in low- and middle-income countries, and about 80% of global NCD-related deaths occur in these countries. Life-style changes and decreases in mortality from infectious diseases have resulted in a shift to rising NCD burdens in sub-Saharan Africa, with regional mortality caused by NCDs projected to surpass by 2030 the sum of deaths caused by all of communicable, maternal, perinatal and nutritional diseases. Cardiovascular diseases like diabetes mellitus and arterial hypertension are among the major causes of morbidity and mortality attributable to the NCDs. There is therefore the need for such organized action that improves care for diabetes mellitus and arterial hypertension in countries in sub-Saharan Africa. This action would involve identifying and promoting access to pragmatic and accurate diagnostic algorithms; determining the burden of target organ damage at community level as an indication of cardiovascular risk; as well as identifying or developing workable models of care delivery in the community to increase access to care, and which could be possibly scaled up.
This thesis aimed to evaluate in rural Lesotho the unattended blood pressure measurement protocol, as an approach for accurate population-level diagnosis of arterial hypertension. We further aimed to uncover at community-level, the rate of target organ damage due to diabetes mellitus and arterial hypertension; as well as summarize in a scoping review, available community-based care models for management of diabetes mellitus among non-pregnant adults in sub-Saharan Africa.
A large multi-disease population-based survey involving 6108 participants was conducted in Lesotho. During this survey, a diagnostic accuracy study was performed which evaluated unattended blood pressure measurement approaches on survey day and on the following day, using 24-hour ambulatory blood pressure monitor as gold standard. Participants with elevated routine survey standard blood pressure as well as age- and sex-matched participants with normal standard blood pressure were recruited. After obtaining the standard blood pressure readings, first unattended blood pressure values were obtained, after which participants were fitted with the 24-hour ambulatory blood pressure monitor. Second unattended blood pressure readings were obtained 24 hours later after retrieving the 24-hour ambulatory blood pressure monitor. Accuracy was determined for routine survey standard blood pressure measurement, and both first and second unattended blood pressure measurements, using area under the receiver operating characteristic curve, with 24-hour ambulatory blood pressure monitor as reference. We found that, compared to standard blood pressure measurement, unattended blood pressure measurement approaches were significantly better correlated with the gold standard 24-hour ambulatory blood pressure monitor. Unattended blood pressure measurement approaches also had lower rates of white coat hypertension, as well as higher areas under the receiver operating characteristic curve, compared to standard blood pressure measurement.
During the population-based survey, we estimated the prevalence of target organ damage such as retinopathy, left ventricular hypertrophy, renal impairment, and peripheral neuropathy. A sub-sample of adults with elevated blood pressure, and/or glycosylated haemoglobin levels indicative of diabetes mellitus, were recruited. Comparators with normal blood pressure and glycosylated haemoglobin levels were also recruited. Among participants with elevated blood pressure, and among those with diabetes mellitus with or without elevated blood pressure, prevalence of retinopathy was 34.6% and 14.4%; and renal impairment was 45.0% and 42.4% respectively. Among those with elevated blood pressure, 65.7% had left ventricular concentric remodeling. Among participants with diabetes mellitus, 32.6% had peripheral neuropathy. The presence of elevated blood pressure or diabetes mellitus were associated with increasing odds of target organ damage. We thus found high rates of undiagnosed target organ damage among adults with elevated blood pressure and/or diabetes mellitus at community-level in rural Lesotho.
For the scoping review, we described different models of community-based care for non-pregnant adults with type 2 diabetes mellitus in sub-Saharan Africa, and synthesized the care outcomes in terms of engagement in care, blood sugar control, acceptability, as well as target organ damage. Additionally, we critically appraised the different models of care, and compared community-based to facility-based care when data were available. Following extensive search of several databases, supplemented with backward and forward citation searches, during which we retrieved 5,335 unique studies, only four studies met criteria for inclusion in the analysis. These four studies described three different community care models: a community-initiated model where diagnosis, treatment and monitoring occurred primarily in the community, and reported higher linkage and engagement in care compared to the corresponding facility model; a facility-originated community model where after treatment initiation in a clinic or hospital, substantial parts of follow-up care was offered at community level; and an eHealth model which reported high acceptability for both patients and care providers. All four studies were at high risk of bias, with mixed results on blood glucose control, and no reported outcomes on target organ damage. Thus, we conclude that evidence on community-based models of care for persons with type 2 diabetes mellitus is scant. Despite the high acceptability of community-based care, there was no conclusive data on effectiveness in blood sugar control, and preventing complications.
Overall, this thesis provides evidence that unattended blood pressure measurement approaches are better than the widely used standard blood pressure measurement, and should be included in blood pressure measurement guidelines for population level screening, diagnosis and follow-up. We also uncovered high rates of undiagnosed target organ damage among adults with elevated blood pressure and or diabetes mellitus, emphasizing the importance of regular prevention and screening activities in the setting. Finally, community-based care could potentially improve care for type 2 diabetes mellitus given its high acceptability, however more high-quality research is needed with clinically relevant endpoints.