Background:
Individuals living with HIV/AIDS have a higher risk
of cardiovascular complications, including hypertension. We, therefore, assess
the prevalence of hypertension and its association with Tuberculosis in HIV
patients on ART in Bagamoyo district eastern Tanzania.
Methods:
This was a cross-sectional study involving
HIV-infected individuals on ART, consecutively enrolled from two selected care
and treatment clinics (CTC), between March and May 2019. Hypertension was
defined as systolic blood pressure (SBP) ≥ 140 mm Hg, diastolic blood pressure
(DBP) ≤ 90 mm Hg or being on-ant hypertensive medication regardless of blood
pressure measurement on the day of the visit.
Results:
We investigated 328 HIV patients on ART, 64.6% were
female, 92.68% on non-protease inhibitors, 0.61% had current TB and 14% had a
history of Tuberculosis in the past 5 years. The overall prevalence of
hypertension in HIV patients on ART was 29.3% and it was significant and
positively associated with increasing age, obesity, family history of
hypertension, and, current history of TB. However, having a history of
Tuberculosis in the past 5 years was not associated with increased odds of
having hypertension.
Conclusion:
The prevalence of hypertension in HIV patients on
ART was higher and it was associated with traditional risk factors and the
current history of tuberculosis and but not with a history of Tuberculosis in
the past 5 years. Regular monitoring of blood pressure is crucial among
HIV/AIDS patients attending HIV outpatient clinics.
Keywords: HIV, Hypertension, ART, CTC, Tuberculosis
Abbreviations:
ART: Anti-Retroviral Therapy; BMI: Body Mass Index;
CTC: Care and Treatment Clinic; HIV: Human Immunodeficiency Virus; TB:
Tuberculosis
INTRODUCTION
Effective use
of antiretroviral therapy (ART), has greatly improved the quality of life and
survival of people living with HIV/AIDS [1]. However, the incidence rate and
mortality from cardiovascular risk factors including hypertension are reported
to be growing up [2-4]. For example, in a recent meta-analysis study prevalence
of hypertension was 34.7% among those on ART compared to 12.7% in ART naïve
individuals [5]. In Tanzania, hypertension prevalence of (28.3%) in HIV
patients on ART has been reported at 28.3% which is higher compared to 5.3% in
HIV ART-naïve and 16.3% in HIV negative individuals [6].
Hypertension
(the leading risk factor of deaths) is a growing health problem in individuals
living with HIV/AIDS [7,8]. However, the contributions of HIV related factors
include Tuberculosis to hypertension have not been extensively investigated in
Tanzania. In addition to the traditional risk factors, hypertension in HIV
patients can be attributed to, inflammation,
ART toxicity and
immune response [9].
Traditional
risks include risks such as increasing age, sex and increasing Body mass index
[10]. However, it’s unclear whether traditional risk factors may interact with
HIV related factors such as Tuberculosis (TB) to increase the risk of
hypertension.
Evidence exists
that TB may contribute to overall cardiovascular risk including hypertension
perhaps through inflammation and autoimmune processes [11,12]. Although TB is
the most prevalent and severe co-infection in HIV patients [13,14], little is
known about its association with hypertension in HIV patients, especially in
developing countries.
Therefore, we
undertook a cross-sectional study to investigate the prevalence of hypertension
and its association with TB in HIV patients on ART adjusting for potential
confounders. To the best level of our knowledge, this cross-sectional study is
the first of its kind to investigate the association between TB and
hypertension among HIV patients on ART while adjusting for confounders.
METHODS
Study design and location
We conducted a
cross-sectional study involving HIV patients who were on ART between March and
April 2019, in Bagamoyo district, eastern Tanzania. The district is located in
the coastal region with an HIV prevalence rate of 6.4% [15]. Data were
collected from 2 public clinics which were purposely selected based on their
relatively large size and presence of patient’s record database (computer-based
record system). These clinics provide services to individuals living with
HIV/AIDS based on national HIV/AIDS guidelines [16].
The inclusion
criteria were being HIV positive, aged above 18, on ART, who gave consent for
participation. Women who reported to be pregnant and those on contraceptive
pills were excluded. The patients were then consecutive enrolled until the
target sample size of 328 was achieved.
Blood pressure measurement
Blood pressure
was measured in the right arm, using a mercury sphygmomanometer of appropriate
size, with individual participants sitting in a relaxed position and upright
position [17], two readings were taken 10 min apart and an average of two
readings was used. Hypertension was defined as systolic blood pressure (SBP) of
≥ 140 mm Hg, diastolic blood pressure (DBP) of ≥ 90 mm Hg [17] or taking
ant-hypertensive medications regardless of blood pressure findings.
Anthropometric measurement
Body weight
(accuracy of 0.1 kg) was measured using Seca patients weighing machines with
individual participants at minimal clothes and wearing no shoes. Body height
was measured using a stadiometer (accuracy of 0.1 cm) participant wearing no
shoes. Body mass index (BMI) was calculated using the formula: weight in
kilogram (kg) divided by the square of height in meters (kg/m2). BMI
was categorized and defined using the WHO protocol as follows, underweight
<18.5 kg/m2, normal body weight 18.5-24.9 kg/m2,
overweight 25-29.9 kg/m2 and obese ≥ 30 kg/m2 [18].
Collection of socio-demographic and HIV related
information
The study used
a structured questionnaire administered by trained health care workers (nurses
and doctors) was used to gather information with respect to participants’
socio-demographic, family history of hypertension, current history of
tuberculosis and history of tuberculosis in the past 5 years.
The following
information was extracted directly from patient record card or computerized
patient database system: Duration since HIV diagnosed, Recent CD4+ cell count,
the current class of ART medication, individual combination therapy and
duration on ART medication.
Definition of terms
Recent CD4+ cell
count was defined as the amount of CD4+ T cell count which was measured in the
past 6 months. Current TB was defined as currently being on anti-TB medication
after sputum analysis or chest radiography. History of TB in the past 5 years
was defined as being on anti-TB medication for at least 6 months within the
last 5 years.
Study variables
The outcome
variable of interest was hypertension defined as blood pressure ≥ 140/90 mm Hg
or being on ant-hypertensive medication. Exposure variables of interest during
the analysis were current TB/HIV co-infection and the history of TB in the past
5 years.
Data management and analysis
Data was
collected using a study questionnaire, then coded using a codebook followed by
the manual entrance in an excel sheet. Before data entry in the excel sheet
completed questionnaire was reviewed for completeness and clarity. Before data
analysis, another review was done for errors, missing data, and
inconsistencies. The analysis was done using Stata software version 13.
We included 328
participants in the final analysis and 33 participants had missing data
regarding the recent CD4+cell count. Recent CD4+ cell count was defined as the
one which was taken within the last 6 months. In 33 participants with missed
data on CD4+ cell count, they had CD4+ cell count either not taken at all or
taken in a period of more than 6. A descriptive analysis (percentage) was used
to summarize the data. Logistic regression, both univariate and multivariate
analysis was performed to establish the risk factors of hypertension. In the
multivariate analysis, we included factors with p-value ≤ 0.005, age, sex and the
current class of ART.
ETHICAL APPROVAL
The study was
approved by institutional review of the Ifakara Health Institute, Bagamoyo
district executive director office as well as the authority of the respective
health facility. Written informed consent was obtained from all study
participants prior to study procedures.
RESULTS
Table 1 summarizes the
socio-demographic and TB characteristics of the participants. We included 328
HIV infected individuals who were on ART for the analysis. Out of all
participants, 212 (64.6%) were female and 116 (35.4%) male. In the description
of the age categories, 132 (40.24%), 151 (46.06%) and 45 (13.72%) were
individuals aged 18-39, 40-59 and ≥ 60, respectively. Out of 328, 89 (25%) of
the participants were either obese or overweight. Current alcohol drunker and
smoking cigarettes were observed in 42 (12.8%) and 17 (5.18%), respectively.
Out of 328, 2
(0.61%) patients had HIV/TB co-infected and 46 (14%) of patients had a history
of TB in the past 5 years (Table 1).
There were 304 (92.68%) patients on non-protease inhibitors and 24 (7.32%) on
protease inhibitors, with the majority of patients 285(86.89%) were on
Tenofovir-based combination therapy and the rest were either on Zidovudine
based combination therapy or Atazanivir (Table
1). Data on CD4+ cell count in the last 6 months was available in 25
(8.47%), 75 (25.42%), 75 (25.42%) and 120 (40.68%) patients had CD4+ cell
count, <100, 100-349, 350-499 and ≥ 500, respectively (Table 1).
In our current
study, the overall prevalence of hypertension in HIV patients on ART was 96
(29.3%). According to gender, the prevalence was 33 (28.5%) in males and 63 (29.7%)
in females (Table 2). Regarding TB
infection, the prevalence of hypertension was 1 (50%) in those with current
TB/HIV and 15 (32.6%) in those with a history of TB in the past 5 years (Table 2).
In
univariate logistic regression analysis, the factors that were significantly
associated with increased odds of having hypertension were: increasing age,
higher BMI, family history of hypertension and non-protease inhibitors (Table 3). The odds for hypertension
were highest among individuals ≥ 60 years of age, odds ratio 5.71 (2.72-12.01) <0.001
and those 40-59 years of age had an odds ratio of 2.48 (1.40-4.37) <0.001 (Table 3). Moreover, regarding body
mass index obese hold the highest odds ratio of 3.3 (1.60-6.66) <0.001 and
overweight 1.70 (0.89-3.25) <0.001 (Table
3). A family history of hypertension and non-protease inhibitors had an
odds ratio of 2.64 (1.36-5.15) <0.001 and 3.09 (0.89-10.6) <0.001,
respectively (Table 3).
In the
multivariate analysis, HIV related factors that were independently associated with
increased odds of having hypertension were, non-protease inhibitors 4.31 (1.16-16.03)
<0.001, current TB/HIV co-infection 3.13 (0.12-80.41) <0.001, Zidovudine
4.66 (0.91-23.99) <0.001 and tenofovir 4.27 (1.15-15.96) <0.001.
However, recent CD4+ count and history of TB in the past 5 years were not
associated with increased odds of hypertension (Table 4).
DISCUSSION
In this
cross-sectional study analyzing the prevalence of hypertension and its
association with TB among HIV patients, we found the prevalence of hypertension
to be 29.3%. We also observed that the odds of having hypertension were
significantly associated with increasing age, obesity, and family history of
hypertension and non-protease inhibitors. Current TB/HIV co-infection was found
to increase the odds of having hypertension in multivariate analysis.
The high
prevalence (29.3%) in our current study appears similar to that of the observed
prevalence in previous studies in HIV patients [5,6]. This strengthens the
evidence that the prevalence of hypertension is higher in HIV patients on ART.
We also
observed factors that were significant and positively associated with increased
odds of hypertension which included: increasing age, obesity and family history
of hypertension. These findings are consistent with previous studies [19,20].
This supports the evidence that traditional risk factors are potential predictors
of hypertension even in HIV patients.
The interaction
between TB infection and hypertension in HIV patients has been reported in the
literature [11]. The possible mechanism by which TB can cause hypertension is
through the inflammatory process which can end up with atherosclerosis [11].
Furthermore, TB can contribute to hypertension, because it can lead to diabetes
mellitus [21] and diabetes mellitus itself is the risk factor of hypertension
[22]. Additionally, hypertension may occur secondarily from renal failure after
TB causing extensive destruction of kidney parenchyma tissues [23]. In our
current study, we found that current TB/HIV co-infection increases the odds of
having hypertension 3.13 (0.12-80.41) <0.001 in multivariate analysis. This
result differs from the study in Dare Salaam Tanzania which found no
significant association between current TB/HIV co-infection and hypertension
[24]. However, we cannot justify the association between current TB and
hypertension based on 2 patients with current TB infection which is a very
small number to conclude. Therefore, in our current study, the interpretation
regarding the association between current TB and hypertension in HIV patients
on ART should be made with caution.
In our current
study, we also found that having a history of TB in the past 5 years did not
increase the odds of having hypertension, contrary to the previous study in Dar
es Salaam, Tanzania which reported a protective effect of prior history of TB
against hypertension [24]. An important difference to note is that in our
current study we limited the history of the previous TB to within 5 years while
the study by Njelekela et al. [24], had no time limit concerning the prior
history of TB. We recommend further studies to investigate more about the
association between TB and hypertension in HIV patients on ART.
CONCLUSION
The prevalence
of hypertension in HIV patients on ART was higher and it was associated with
traditional risk factors but not with the history of Tuberculosis in the past 5
years. We cannot justify the association between current TB infection and
hypertension based on 2 patients with current TB infection which is a very
small number to conclude.
Routine
screening of blood pressure and health education, body weight control, healthy
diet, physical activity should be emphasized as essential components of
treatment and care of HIV patients. We recommend further longitudinal studies
to explore more on the association between TB and hypertension in HIV patients.
We faced the
followings limitations: being cross-sectional we cannot establish causality
between selected exposure variable and outcome variable. Also, we did not
include HIV-negative individuals to make a comparison between the two groups.
Again we cannot justify the association between current TB infection and
hypertension based on 2 patients with current TB infection which is a very
small number.
Despite the
mentioned limitations, this study provided important results regarding the
association between TB and hypertension in HIV patients on ART, particularly in
low-income countries.
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Table 3
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Table 5
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Table 7
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Table 8
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