Blood pressure control among hypertensive patients of tribal origin attending a primary care centre in Kerala

INTRODUCTION

Hypertension is a condition in which the blood vessels have abnormally high pressure for an extended period.¹ The burden of hypertension is disproportionately felt in low and middle-income countries, which accounts for two-thirds of all case.² Hypertension is a primary cause of mortality worldwide, impacting one out of every four men and one out of every five women. The term “silent killer” is commonly used to describe hypertension. The majority of people are unaware that they have hypertension since it generally has no warning signs or symptoms. The reported prevalence of hypertension in tribal populations varies from 10% to 55.5% in different regions and states of India.³ Two-thirds of older Indian adults had hypertension, with the majority being undiagnosed or diagnosed but not adequately controlled.⁴ According to a systematic review and meta-analysis by Rizwan et al the pooled prevalence of primary hypertension among adult tribal populations of India was found to be 16.1%.⁵

“Tribals” are a group of people who live in isolation in natural, unpolluted environments far from civilization, keeping their traditional values, practices, beliefs, and myths, and are considered the land’s autochthonous people. The world’s second largest concentration of tribal people is found in India. Indian tribes account for approximately 8.3% of the total population of the nation, with a population of 8,17,420, Wayanad is the least inhabited district and has the largest number of tribals at 1,51,443.⁶ According to the 2011 Indian census, Kerala’s scheduled tribe population was 4,84,839 individuals.⁷ Paniyas, Kurumas, Adiyars, Kurichyas, Ooralis, Kattunaikkans, and Uraali Kurumas are among the district’s native Adivasis.⁸ According to research, with respect to recent changes in social structure and cultural patterns, tribes in India are undergoing a similar transformation. Substantive changes can be marked in their food pattern and intake practices. The incidence of diseases like cardiovascular disease, and others has increased significantly.⁹ Hypertension is frequent among Kerala’s tribal population, especially among the middle-aged and elderly, men, illiterates, persons from lower socioeconomic classes, people who have sedentary occupations, drink alcohol, and those who are overweight or obese.¹⁰ A study was carried out in a primary tribal care centre in Kainatty, Wayanad, to assess the proportion of uncontrolled hypertension among the hypertensive indigenous people and to determine adherence to medication.

METHODS

A cross-sectional study was planned and carried out from August to October 2021 at a tribal primary care centre in Wayanad. The study was conducted among the adult tribal patients visiting the primary care centre run by a charitable trust.

All persons of tribal origin above the age group of 18 years visiting the health centre were included in the study while excluding pregnant and lactating women. The minimum calculated sample size was 146 (4pq/d²), using the prevalence of a study, conducted among the Kani tribe in Thiruvananthapuram district, Kerala where uncontrolled blood pressure among hypertensives was 40.6%, with a 95% confidence level and relative precision of 20%.¹¹

Hypertension is defined as office systolic blood pressure ≥140 mm of Hg and/or diastolic blood pressure values ≥90 mm of Hg.¹² Participants whose hypertension under control are those who were diagnosed as hypertensives and may/may not be on medication with a systolic blood pressure <140 mm of Hg and diastolic blood pressure <90 mm of Hg. Participants with uncontrolled hypertension are those who were diagnosed as hypertensives and are on medication for more than 1 month with a systolic blood pressure ≥140 mm of Hg and/or diastolic blood pressure values <90 mm of Hg on taking an average of two blood pressure readings.

Sampling technique

All the patients of tribal origin visiting the primary care outpatient department diagnosed with hypertension for more than 1 month were included in the study. Pregnant and breastfeeding women were excluded from the study.

Study tool

A semi-structured questionnaire was used for data collection. Each study participant was interviewed for collecting information regarding demographic details like age, sex, tribe, education, marital status, occupation, ration card colour, type of family, alcohol use and tobacco use. The questionnaire was administered through interview technique in the local language Malayalam after explaining regarding study and obtaining written informed consent. Ethical clearance was obtained from the institutional ethics committee, Amrita Institute of Medical Sciences (ECASM-AIMS 2021-386). Physical examination was carried out to measure the height, weight, and body mass index (BMI-weight in kg/height in m²). BMI was classified based on WHO Asian Pacific classification.¹³ A mercury sphygmomanometer was used to check blood pressure. Along with the blood pressure recorded on the day of the visit, the last recorded blood pressure written in the patient’s outpatient case sheet was taken as the past reading. The average of these two readings was taken to assess control of blood pressure. The measurement of weight (kg) was taken using an analogue weighing machine. Measurement of height (cm) was taken using roll ruler wall mounted growth stature meter, the reading parallel to the red line in the vertical measuring bar was taken as a measurement for height. The Four-item Morisky Green Levine scale (MGLS) was used to evaluate the adherence to the medical regimen of patients with hypertension treated with drugs.¹⁴

Statistical analysis

The data collected from the study was entered into Microsoft excel and the analysis was done using IBM SPSS statistics for windows, version 21. Descriptive statistics for continuous variables were summarized as mean and standard deviation. The prevalence of uncontrolled hypertension in the hypertensive tribal population was summarized as percentages with 95% CI. A Chi-square test was used to assess the association between sociodemographic profile and uncontrolled hypertension. The p value <0.05 was considered as statistically significant. Bivariable and multivariable logistic analysis were used to identify the independent predictors for uncontrolled blood pressure.

RESULTS

The mean age of the study population was 56.8±12.01 years, with the majority being females (64.7%). The majority of the participants were married (95.8%), about 41% of people belonged to the Paniyas community, and nearly half of the study participants had no formal schooling. The majority of the study participants (92.8%) belonged to the below poverty line (BPL) category. About a half of the respondents (46.1%) used some form of tobacco. Among the study participants, 65.9% never consumed alcohol while 34.1% had a history of alcohol consumption. Among 34.1% who had a history of alcohol consumption, 16.2 % were former drinkers, 8.4% were social drinkers and 9.6% were current drinkers (Table 1).

**Fisher’s exact test.

*Adjusted for gender, education, occupation, alcohol, MGLS Score.

The proportion of uncontrolled blood pressure among the hypertensive tribal population was high at 70.7% (95% CI 63.79-77.60).

The vast majority of the participants had a history of hypertension ≤10 years. Among the study participants, one-third of them had a family history of hypertension, a large portion of study participants had modified their diet and limited their salt intake after diagnosis of hypertension (81.4%) (Table 1).

Tobacco users in any form among the tribal population were high (46.1%), which included smoking (3.6%) and in chewable form (42.5%). Most of the study participants had regular monitoring of blood pressure (90.4%), a small portion (12%) of them had complications of hypertension such as heart attack, stroke, kidney, and vision impairment. The proportion of underweight was higher at 21.6% than obese, 16.2%. Among the study population, 32.9% had other specific diseases like gastritis, gastroesophageal reflex disease (GERD), hypothyroidism, hyperthyroidism, and gout. Among the study participants, 22.8% had coexisting diabetes mellitus.

A vast proportion of the study population reported that they did not forget to take medication (84.4%). Most of the study participants were not careless about taking anti-hypertensive medications (77.8%). The greater part of the study population didn’t stop the medication when feeling better (89.22%). Most of the study participants (99.4%) didn’t stop medicines when felt worse. The MGLS score ranged from 0-4, and the three levels of medication adherence based on this score; high, medium, and low adherence were 0, 1-2, 3-4 points, respectively.¹⁴ According to MGLS, adherence was found to be high among 68.3%, medium among 26.9% and low among 4.8% of study participants. For the statistical analysis, the mean value of the MGLS score (0.491) was taken as cut-off value: good adherence ≤0.49, poor adherence >0.49. Among participants with uncontrolled blood pressure, poor adherence was found to be 31.7% while 68.3% of participants had good adherence.

Among the study population, 67.7% of study participants had a systolic BP≥140 mmHg and 65.9% of the study participants had diastolic BP≤90 mmHg. A total of 70.7% of the study participants had uncontrolled blood pressure when satisfying the condition of systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg.

Based on the univariate analysis for the association of controlled hypertension with sociodemographic characters and personal habits, the association of education was found to be significant (p value=0.036). The association of alcohol was also found to be significant (p value =0.007) (Table 2).

Bivariable and multivariable logistic analyses were done to identify independent predictors associated with uncontrolled blood pressure. All variables with p values <0.2 during chi-square analysis were entered together to do the multivariate model. Accordingly, variables such as gender, education, occupation, alcohol and MGLS score were entered. Alcohol, education, occupation had statistically significant association with the uncontrolled blood pressure. Accordingly, the multivariate analysis showed alcohol consumption (aOR- 4.303, 95% CI 1.194, 15.50) and lower education (aOR- 6.746, 95% CI 1.283, 35.46) as an independent predictor of uncontrolled blood pressure with p value <0.05 (Table 3).

DISCUSSION

The proportion of uncontrolled blood pressure among the hypertensive tribal population was high at 70.7% (95% 63.79-77.60). The association of uncontrolled hypertension with education was found to be significant (p value 0.036) with those with a lower education having poor control. Uncontrolled blood pressure was found to be significantly higher among the regular alcohol users (p=0.007). A majority (68.3%) of the study participants had a high adherence according to the MGLS score. On multivariate analysis, alcohol consumption and lower education status were the independent predictors of uncontrolled blood pressure.

The prevalence of uncontrolled hypertension among the hypertensive tribal population attending the primary care centre in Kainatty was much higher than the Kani tribes of Kerala (40.6%).¹¹ The increased prevalence of uncontrolled hypertension may be because it was a hospital-based study where more sick people are likely to congregate. Tobacco use among study participants was high (46.1%). The high prevalence of uncontrolled hypertension may also be due to the reluctance to make lifestyle changes such as stopping tobacco and alcohol use.

The association of uncontrolled hypertension with education was found to be significant (p value 0.036). In a study among hypertensives in tribals, higher education was found to be significantly protective.¹⁰ However there were no similar studies on blood pressure control among tribal hypertensives. In a population-based study among the Kani tribe in Thiruvananthapuram, 13.1% did not have formal education whereas in this hospital-based study 47.3% of the tribal participants did not have any formal education and 16.8% of them had high school education while 11.4% of the Kani tribe had high school education. Because the majority of the participants were poor, they decided to work to supplement their family's income rather than attend school.

The alcohol users had 4 times higher odds of having uncontrolled hypertension. A similar association was found between alcohol use and hypertension among the adult tribal population of Kerala.¹⁰ The current alcohol consumption is lower than the national prevalence (32%). The pathophysiology underlying the link between alcohol consumption and blood pressure is complex, and several mechanisms have been hypothesised. Endothelial dysfunction, intracellular calcium build-up, activation of the renin-angiotensin-aldosterone system, heightened sympathetic activity, vasoconstriction, and elevated oxidative stress are all probable explanations for the increased blood pressure.¹⁵

The study was done at a tribal primary care centre, the findings cannot be applied to the broader tribal community. The majority of the risk variables were self-reported, which might have been prone to recall bias.

CONCLUSION

The proportion of uncontrolled blood pressure among the hypertensive tribal population was high at 70.7%. Limiting alcohol and improving education appear to be key to attaining target levels of blood pressure control. However, large scale population-based studies are necessary to corroborate these findings.

ACKNOWLEDGEMENTS

We would like to acknowledge all the staff at department of community medicine and public health at Amrita Institute of Medical Sciences, Kochi and also like to extend our gratitude to the study participants and all the staff working at Amrita Kripa Charitable Hospital, Kainatty, Kerala.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the Institutional Ethics Committee

REFERENCES

1. 1. Hypertension. WHO fact sheet. WHO. Available from: https://www.who.int/news-room/fact-sheets/detail/hypertension. Accessed on 20 May 2022.
2. 2. Hypertension. Health topics. WHO. Available from: https://www.who.int/westernpacific/health-topics/hypertension. Accessed on 20 May 2022.
3. 3. Tripathi N. Prevalence of hypertension in Indian tribal adult population: a scoping review. J Adv Res Med. 2020;07:5-13.
4. 4. Farron MR, Kabeto MU, Dey AB, Banerjee J, Levine DA, Langa KM. Hypertension and cognitive health among older adults in India. J Am Geriatr Soc. 2020;68 Suppl 3:S29-35.
5. 5. Rizwan SA, Kumar R, Singh AK, Kusuma YS, Yadav K, Pandav CS. Prevalence of hypertension in Indian tribes: a systematic review and meta-analysis of observational studies. PLoS One. 2014;9(5):e95896.
6. 6. Narain JP. Health of tribal populations in India: How long can we afford to neglect? Indian J Med Res. 2019;149(3):313-6.
7. 7. Population statistics 2011 census. Gov.in. Available from: https://www.stdd.kerala.gov.in/population-statistics-2011-census. Accessed on 30 May 2022.
8. 8. Tribals in Kerala. Kerala Institute for Research Training and Development Studies of Scheduled Caste and Scheduled Tribe. Available from: https://kirtads.kerala.gov.in/tribals-in-kerala/. Accessed on 30 May 2022.
9. 9. Acharya SK, Kshatriya GK. Social transformation, identity of Indian tribes in recent time: An anthropological prospective. Afro Asian J Anthropol Soc Pol. 2014;5(2):73.
10. 10. Meshram II, Arlappa N, Balkrishna N, Rao KM, Laxmaiah A, Brahmam GNV. Prevalence of hypertension, its correlates and awareness among adult tribal population of Kerala state, India. J Postgrad Med. 2012;58(4):255.
11. 11. Sajeev P, Soman B. Prevalence of noncommunicable disease risk factors among the Kani tribe in Thiruvananthapuram district, Kerala. Indian Heart J. 2018;70(5):598-603.
12. 12. Williams B, Mancia G, Spiering W, Al E, Bochud M, Messerli F, et al. 2018 ESC/ESH Guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Cardiology and the European Society of Hypertension. J Hypertens. 2018;36(10):1953-2041.
13. 13. World Health Organization. Regional Office for the Western Pacific. The Asia-Pacific perspective: redefining obesity and its treatment. Sydney: Health Communications Australia; 2000:55.
14. 14. Beyhaghi H, Reeve BB, Rodgers JE, Stearns SC. Psychometric properties of the four-item Morisky Green Levine Medication Adherence Scale among Atherosclerosis Risk in Communities Study (ARIC) Participants. Value Health. 2016;19(8):996-1001.
15. 15. Okojie OM, Javed F, Chiwome L, Hamid P. Hypertension and alcohol: a mechanistic approach. Cureus. 2020;12(8).