The aim of this study was to determine the prevalence and factors associated with hypertension in PWH based on the new hypertension diagnostic criteria.
Prevalence of hypertension
While using the JNC 7 criteria puts the prevalence of hypertension in our study at 16%, the new AHA/ACC criterion shifts the prevalence to 42% representing a 26% shift of those previously considered normotensive into the hypertensive category. The reported prevalence of hypertension in PWH in low- and middle-income countries ranges from 4 to 54% [10, 11]. In ART-treated PWH, a prevalence of hypertension of between 17 to 38% has been reported [12–15] using the JNC 7 criteria, lower than what we reported. However, with the new AHA/ACC criteria, our results indicate an urgent need for intervention. However, further investigations are required to understand the outcomes of hypertension in PWH when using the new hypertension guidelines as previous studies of cardiovascular events, stroke, etc relied on different definitions of hypertension. So we do not know whether the new guidelines will improve the prior epidemiological models.
Factors associated with hypertension in PWH
Among the social-demographic data collected, three were positively associated with hypertension, including the age of participants, employment status and marital status. In the Zambian setting, the patients' age is always recorded, while the rest are non-routine data. The new AHA/ACC does not recommend consideration for employment status, marital status, or level of education when assessing risk for hypertension or treatment. However, most hypertensives in this study were married (46% hypertensive versus 43% normotensive), and in formal employment (31% hypertensive versus 21% normotensive). Furthermore, the JNC 7 and AHA/ACC does not consider the influence of these factors on blood pressure. Here, we suggest that further studies are needed to determine how an individual’s employment status, marital status, and level of education relate to hypertension in low-income countries.
Among dietary and lifestyle non-routinely collected variables, factors such as daily physical activity, the addition of salt at the table, and processed salt intake (negative association) were all positively associated with hypertension (Table 2), and this is in tandem with the recent hypertension report guidelines .
The clinical factors associated with hypertension included BMI, WC, duration on ART, pulse pressure, MAP, mid-BP, FBS, diabetes risk scores, and risk category (Table 3). Among these, only BMI is routinely collected in Zambian hospitals. While BP components such as pulse pressure, MAP, and mid-BP are expected to be different between hypertensive and normotensive, we only included these variables in the analysis to indirectly assess the effect of antihypertensive drugs. It is expected that hypertensive patients taking antihypertensives will present with BP readings similar or lower than those of normotensive individuals except when either the patient has hypertension that does not respond to the current treatment or dues to poor adherence to the hypertension medication. We found in our study that PP, MAP, and mid-BPs were higher in hypertensive patients. This is because all hypertensives in the study had not taken their medication for more than two weeks. Since we did not collect data on adherence to antihypertensive drugs and cannot ascertain the cause for this.
Hypertensive patients had high diabetes risk scores and FBS (Table 3). Often the factors associated with hypertension are likely related to diabetes risk too . Hence, we employed a diabetes risk assessment tool to assess if hypertensive patients were at risk of developing diabetes mellitus type 2 in 10 years. The value for diabetes risk assessment scores has been described from our recent previous study conducted in PWH . Conducting diabetes risk assessment would be cardinal among PWH let alone hypertensive.
We performed a multivariate logistic regression to assess each variable's contribution towards hypertension status (Table 4). Being older [1.0 (1.03, 1.15); AOR 95%CI] was positively associated with hypertension in HIV while those who were overweight (BMI =25-29.9) and obese (BMI equal to or greater than 30) were eight (p=0.043) and twenty-three (p=0.027) times more likely to be hypertensive, respectively. These findings are consistent with another study conducted locally in Zambia  and other studies reviewed . Fasting blood sugar was positively associated with hypertension (p=0.038) as those with higher fasting blood sugars were twice more likely to be hypertensive (1.0, 4.1,95% CI). Being unemployed had reduced effect on hypertension [0.19 (0.04, 0.95); AOR 95% CI]. Unexpectedly, those who added salt on the table had reduced odds [0.17 (0.04, 0.95; AOR, 95%)] for developing hypertension compared to those who rarely or never add salt on the table. These results were contrary to a study conducted in neighbouring Zimbabwe, where adding salt to food at the table (AOR 2.77, 95% CI 1.41-5.43) was an independent risk factor for uncontrolled hypertension. However, the study population was not PWH. In our study, we did not quantify the amount of salt the participants consumed. Hence, further studies are needed to ascertain the role of table salt as a risk factor for hypertension in PWH. Several studies consistently report that higher salt intake is positively associated with BP and hypertension [18–20], albeit not in PWH. A previous study reported that among the Zambian population, salt consumption was more than twice that recommended by WHO . There is a general paucity of studies and no study known to us that has addressed salt intake and its relation to BP and hypertension in HIV. There is also the issue of salt sensitivity which varies among individuals [21, 22]. However, our study was beyond the scope of assessing actual salt quantities and sensitivity.
Compared to those with normal WC (<94 cm men; <88 cm women), individuals with a WC between 94-102 for men and 80 to 88 for females and those with a WC above 102 for men and above 88 for females were sixteen times (1.2, 198.9; 95% CI) and 290 times respectively, more likely to be hypertensive (p<0.05). Individuals with more extended sedentary lifestyles, which is the amount of time spent seated, were more likely to be hypertensive [1.0 (1.00, 1.01); AOR, 95%CI, p=0.021] while minutes of moderate physical activity were associated with lower risk of being hypertensive [0.98 (0.97, 1.00) 95%CI, p=0.048]. These results are consistent with previous studies and the AHA/ACC report on hypertension . Our results provide evidence that several non-routinely collected variables should be incorporated in routine ART services and care to prevent hypertension and its attendant adverse outcomes.
Contextualizing the usage of new AHA/ACC guidelines in low-cost settings in PWH
The treatment and care of PWH previously overlooked the burden of NCD comorbidity such as hypertension. Recently (2018), the Zambian government, through the Ministry of Health integrated hypertension management in PWH (see www.hivst.org). However, the guidelines are not detailed and lack the most critical hypertension diagnosis, treatment, and care emphasized in the new AHA/ACC criteria.
We found in this study that the current routine practice for the measurement of BP in PWH may not be accurate. As shown in Table 6, routine measurements that did not take into consideration the preparation of the patient, such as resting, sitting position, and taking more than one BP measurement, resulted in higher BPs than the standard measurement with median SBP and SDP differences of 3mmHg. As a result, about 4% (7/191) and 12% (23/191) of normotensives would have been misclassified as hypertensive using the JNC 7 and new AHA/ACC diagnostic criteria. All measurement guidelines stipulated in the new AHA/ACC guidelines can be implemented in low-cost settings. Self-monitoring of BP is also encouraged to enhance accuracy in BP measurements and to avoid white coat hypertension.
Using the new AHA/ACC criteria to diagnose hypertension shifted 26% of normotensives into hypertension (Table 5). This is consistent with the AHA/ACC report . The advantage of this is that most of the patients can prevent hypertension-related health complications through lifestyle changes alone, such as reducing salt intake, increased physical activity, reducing sedentary time, and eating more plant-based diets [4, 23, 24]. These changes are feasible in low-cost settings and can potentially reduce the burden and complications of hypertension.
The 10-year risk for heart disease and stroke using the atherosclerotic cardiovascular disease (ASCVD) risk calculator elaborated in the new AHA/ACC guidelines is uncommon in Zambia and SSA countries. ASCVD risk components include age, sex, race, SBP, DBP, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, history of diabetes, smoking status, antihypertensive drug history, history of statin use, and aspirin use. Screening for ASCVD in low-cost settings is feasible, although testing for LDL and HDL is not yet routine at Livingstone Central Hospital.
Our study shows that the new AHA/ACC guidelines are needed. We would, therefore, encourage integrating the guidelines into routine care for PWH.
We did not collect data on drug adherence to antihypertensive medications to ascertain the cause of uncontrolled BPs in hypertensive patients. Further, we did not have a comparison group (HIV negative) to ascertain the effect of HIV and ART on hypertension and factors related to hypertension.