Prevalence and determinants of hypertension among urban tribal communities in Nagaland, India—A community-based study

ABSTRACT

Background:

There is a paucity of data on the burden and factors associated with hypertension among the Nagas (collective term for tribal ethnic groups predominantly residing in Nagaland) living in an urban environment. Insights from this study will aid in mapping focused community-based and primary care interventions for hypertension.

Objectives:

To determine the prevalence and risk factors associated with hypertension among Nagas aged 30–50 years residing in urban Dimapur, Nagaland.

Methods:

A community-based cross-sectional study was conducted between January and July 2019. This study screened 660 participants for hypertension using a digital blood pressure apparatus. A semi-structured questionnaire was used to assess the risk factors, and anthropometric measurements were recorded using standard guidelines.

Results:

The prevalence of hypertension and pre-hypertension was 25.9% and 44.5%, respectively. Non-modifiable risk factors such as male gender (adjusted odds ratio [AOR]: 2.02; 95% confidence interval [CI]: 1.32–3.09), age > 40 years (AOR: 2.32; 95% CI: 1.57–3.41), family history of hypertension (AOR, 1.87, 95% CI: 1.19–2.92) and modifiable risk factors such as current alcohol consumption (AOR: 2.05; 95% CI: 1.27–3.31), high/very high perceived stress (AOR: 2.15; 95% CI: 1.28–3.62), lack of participation in stress relief activities (AOR: 2.08; 95% CI: 1.17–3.71) and overweight/obesity (AOR: 2.26; 95% CI: 1.55–3.30) were independently associated with hypertension in this study.

Conclusion:

To avert an impending health crisis in this community, a multipronged approach involving primary-care/family physicians, culturally appropriate awareness, and targeted community-based screening programs with an adept referral system must be implemented to curtail this emerging threat.

Introduction

The World Health Organization (WHO) has rated hypertension as one of the most important causes of early death worldwide.[1] It has been projected that the prevalence of hypertension among adults will increase by about 60% to a total of 1.56 billion in 2025, of which two-thirds of the burden would be in developing countries such as India.[2,3] Simple interventions implemented in primary care settings, such as early detection, consistent lifestyle modifications, and initiation of drug therapy, considerably lower blood pressure (BP), decreasing the incidence of cardiovascular events.[4] Further, primary prevention of established modifiable risk factors like unhealthy diet, physical inactivity, consumption of tobacco and alcohol, and being overweight or obese are also crucial in preventing hypertension.[5]

Nearly 90% of the population living in Nagaland are tribal or indigenous people and are classified as a scheduled tribe (Nagas are disadvantaged communities or groups of people listed in a schedule of the Indian constitution under article 342 by the Government of India).[6] With globalization, the Nagas are rapidly transitioning from traditional living to adopting a more modernized lifestyle.[7] Recently, there has been a transition in occupational preferences—from an agrarian society to white collar jobs and a preference for westernized fast foods that are soon replacing traditional food on their plates. Recent migration from the rural areas has led to a rapid expansion of the urban boundaries, thus stretching an already overwhelmed public service system.[8]

The recent National Family Health Survey-5 (2019–2020) indicated that the prevalence of hypertension among females and males aged between 30 and 49 years in Nagaland was 22.9% and 29.9%, respectively, which is comparable with estimates from larger cities in other states.[9] Tushi et al.[10] reported a high prevalence of individual risk factors for non-communicable diseases (NCD), including hypertension, in a rural community in Nagaland; however, specific risk factors associated with hypertension were not determined. To alleviate escalating numbers of NCDs, especially hypertension, facility-based NCD clinics were set up in all the district hospitals and selected community health centers by the government to facilitate screening and treatment since 2014.[11] Population-based screening has also been introduced in selected rural areas of the state and is slowly gaining momentum; however, city dwellers have to avail of these services from district hospitals which can be challenging to access.[11]

This study aimed to determine the prevalence and determinants of hypertension among tribal communities in Nagaland, India. The burden of hypertension and pre-hypertension will inform primary care physicians, family physicians, and health authorities of the magnitude of this disease. The data will also help predict the burden of complications that may arise if blood pressures in the community continue to follow the current trend. The social and cultural practices are unique to this tribal community, so it is imperative to understand the modifiable and non-modifiable factors associated with hypertension specific to this community in an urban environment. Identifying specific risk factors will aid primary health care workers and family physicians in focusing on high-risk individuals. This will also steer policymakers to plan and implement community-based primary care interventions to mitigate this issue.

Material and Methods

Setting and study design

This community-based cross-sectional study was conducted in Diphupar ‘A,’ Dimapur Nagaland, India, from January to July 2019. Dimapur is the district headquarters and is the most densely populated city in Nagaland, home to nearly 2,00,000 people. The health needs are catered to by a government-run district hospital and a few private hospitals located mainly in the city center. In contrast to the topography of the rest of Nagaland, Dimapur is located in the plains bordering Assam, the neighboring North-eastern state.[12]

Sample size and selection of participants

Prevalence of hypertension in Dimapur (21.5%) was used to calculate the sample size (660) with a permissible error of 15% with a 95% Confidence Interval (CI).[13] The list of all households was acquired from the Diphupar ‘A’ area council census data, and the list of potential households was randomly selected using a random integer generator. Naga adults aged 30–50 years residing in the selected households were approached and invited to participate in the survey. People with severe cognitive impairment, pregnant women, and lactating mothers were excluded.

Study tools and techniques

Data were collected door to door using a pilot-tested, back-translated, semi-structured questionnaire administered by the trained interviewer in Nagamese, the local language. The questionnaire included the socio-demographic characteristics of the participants, the WHO STEPS instrument for chronic disease risk factor surveillance,[14] cardiovascular risk assessment,[15] and the Perceived Stress Scale (PSS) by Sheldon Cohen.[16] Modified BG Prasad socioeconomic scale (SES) -2018 was used to determine the socio-economic status and modified Kuppuswamy scale to classify the occupational categories.[17,18] Height (up to the nearest 1 mm) and weight (up to the nearest 100 g) were measured using standard guidelines.[14] The BP of the participants was assessed using an automated oscillometric machine (HEM-7113, Omron Health Care Co., Kyoto, Japan) calibrated weekly. The average of 3 readings, rounded off to the nearest whole number, was used to estimate the final BP of the respondents. The BP was recorded at intervals of 5 min (usually in the afternoon) in a sitting position on the left arm. Body Mass Index (BMI) and BP were categorized using standard guidelines.[19,20] The participants with high BP were referred to the nearest healthcare center or hospital for further management.

Statistical analysis

Epi-Info 7 (CDC, Atlanta, GAUSA, 2011) was used to enter the data and SPSS 16 (SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc.) for the analysis. The outcome variable assessed was hypertension, defined as the mean systolic pressure ≥140 mmHg or diastolic pressure ≥90 mmHg.[21] Descriptive statistics are presented as proportions. Pearson’s Chi-square test of significance was carried out at a 5% significance level (P < 0.05) with a 95% CI to identify associations between risk factors and hypertension. The statistically significant predictors in the bivariate analysis were included in the multivariate logistic regression model with the outcome variable as hypertension. The adjusted odds ratios with 95% CI were calculated independently for the risk factors. The statistically significant exposure variables in the bivariate analysis were gender, age, family history of hypertension, family history of diabetes, tobacco/alcohol consumption, saturated oil consumption, perceived stress, participation in stress relief activities, and BMI.

Ethical considerations

The study was approved by the Institutional Review Board and Ethics Committee (IRB Min No: 11776, dated 07.01.2019) with prior permission from the Diphupar area council. Written informed consent was obtained from the participants after providing the details using an information sheet in Nagamese.

Results

Overall, 660 individuals consented to participate in the study, of which 306 (46.0%) were male and 355 (54.0%) were female. The mean age of the study participants was 38.33 years (standard deviation (SD)—6.4). Most participants were married (416, 63.0%), completed high school (531, 80.6%), unemployed (303, 46.0%) or belonged to the upper-class SES category (290, 44.0%). The details of the participants’ background characteristics are listed in Table 1.

Table 1.

Background characteristics of the participants (n=660)

Characteristics	Category	n (%)
Gender	Male	305 (46.0)
	Female	355 (54.0)
Age (years)	30-35	269 ( 41.0)
	36-40	157 (24.0)
	41-45	119 (18.0)
	46-50	115 (17.0)
Marital status	Married	416 (63.0)
	Unmarried	209 (32.0)
	Separated/divorced/widowed	35 (5.0)
Education	No formal education	24 (3.6)
	Primary school	30 (4.5)
	Middle school	75 (11.4)
	High school	182 (27.6)
	Higher secondary school	93 (14.1)
	Diploma/certificate/under-graduate	4 (0.7)
	Graduate	202 (30.6)
	Post-graduation and above	50 (7.6)
Occupation (Kuppuswamy classification)	Professional	6 (1.0)
	Semi-professional	146 (22.0)
	Clerical/shop/farm	122 (18.0)
	Skilled workers	24 (4.0)
	Semi-skilled workers	40 (6.0)
	Unskilled workers	19 (3.0)
	Unemployed	303 (46.0)
BG Prasad Socio-economic status	Lower class (Rs. 985 and below)	4 (1.0)
	Lower middle class (Rs. 986-1971)	29 (4.0)
	Middle class (Rs. 1972-3286)	106 (16)
	Upper middle class (Rs. 3287-6573)	231 (35)
	Upper class (Rs. 6574 and above)	290 (44)

The prevalence of hypertension was 25.9 (95% CI: 19.4–32.4), with mean systolic BP—127 mmHg (SD—16.2) and mean diastolic BP—82 mmHg (SD—16.1), respectively. The prevalence of pre-hypertension was 44.5% (95% CI: 36.8–52.2). More males (101,33.0%) had hypertension compared to females (70, 20.0%) [Table 2]. Of the 171 participants with high BP recorded, 43 (25.1%) participants already knew they had hypertension.

Table 2.

Prevalence of hypertension and pre-hypertension stratified by gender

Blood pressure categories (mmHg)	n (%)
	Male (n=305)	Female (n=355)	Total (n=660)
Normal (<120/<80)	57 (19.0)	138 (39.0)	195 (29.6)
Pre-hypertension (120-139/80-89)	147 (48.0)	147 (41.0)	294 (44.5)
Hypertension (≥140/≥90)	101 (33.0)	70 (20.0)	171 (25.9)

Family history of diabetes and hypertension were reported by 113 (17.0%) and 150 (23.0%) participants, respectively [Table 3]. The prevalence of tobacco use in any form, i.e., both smoking and smokeless tobacco, among the participants was 57.6% (382). Although a third (33.4%) of the male participants currently smoked, 61.5% (406) reported regular second-hand exposure to smoking. The overall prevalence of current alcohol consumption was 22.7% (149). Only 4.7% (31) of the population were consuming ≥ five servings of fruits and vegetables daily, and 15.3% (101) were consuming ≤ five grams of salt per day as recommended by the WHO. Many (214, 32.4%) reported regularly using saturated oils (lard, ghee, butter, and cheese) for household cooking. The majority (528, 80.0%) of the participants were engaged in highly active physical activity. Around 25.4% perceived no/low stress, while 61.4%, 12.9%, and 0.3% perceived moderately low, high, and very high-stress levels, respectively. Only 10.5% (69) of the participants did not participate in activities that alleviate stress (prayer/meditation, exercise/stretching, community/social events, or playing with pets). The proportion of participants who were underweight, normal, overweight, and obese (I, II, III) based on their BMIs were 3.9%, 53.2%, 32.0%, and 10.9%, respectively.

Table 3.

Multivariate logistic regression model for independent factors associated with hypertension

Characteristics	Category	Total (n=660)	Hypertension		χ2, P	UOR (95% CI)	χ2, P	AOR (95% CI)
			Yes (n=171), n (%)	No (n=489), n (%)
Gender	Male*	305	101 (33.0)	204 (67.0)	<0.001	2.02 (1.42-2.87)	0.001†, ‡	2.02 (1.32-3.09)
	Female	355	70 (20.0)	285 (80.0)
Age	>40 years	234	87 (37.0)	147 (63.0)	<0.001	2.41 (1.69-3.44)	<0.001†, ‡	2.32 (1.57-3.41)
	≤40 years	426	84 (20.0)	342 (80.0)
Family history of hypertension	Yes	150	56 (37.0)	94 (63.0)	<0.001	2.05 (1.39-3.02)	0.006†, ‡	1.87 (1.19-2.92)
	No	510	115 (23.0)	395 (77.0)
Family history of diabetes	Yes	113	42 (37.0)	71 (63.0)	0.003	1.92 (1.25-2.95)	0.14	1.45 (0.89-2.38)
	No	547	129 (24.0)	418 (76.0)
Currently smoking	Yes	102	35 (34.0)	67 (66.0)	0.035	1.62 (1.03-2.55)	0.736	1.1 (0.64-1.89)
	No	558	136 (24.0)	422 (76.0)
Currently consuming alcohol	Yes	147	57 (39.0)	90 (61.0)	<0.001	2.22 (1.50-3.28)	0.003†, ‡	2.05 (1.27-3.31)
	No	513	114 (22.0)	399 (78.0)
Cooking with saturated oils/fat	Yes	214	68 (32.0)	146 (68.0)	0.017	1.55 (1.08-2.23)	0.1	1.4 (0.94-2.09)
	No	446	103 (23.0)	343 (77.0)
Perceived stress	High and very high stress	85	33 (39.0)	52 (61.0)	0.004	2.01 (1.25-3.24)	0.004†, ‡	2.15 (1.28-3.62)
	No and low stress	575	138 (24.0)	437 (76.0)
Participation in stress relief activities	No	69	26 (38.0)	43 (62.0)	0.018	1.86 (1.10-3.13)	0.013†, ‡	2.08 (1.17-3.71)
	Yes	591	145 (25.0)	446 (75.0)
BMI Category	Overweight/obese	283	102 (36.0)	181 (64.0)	<0.001	2.52 (1.76-3.59)	<0.001†, ‡	2.26 (1.55-3.30)
	Normal/under-weight	377	69 (18.0)	308 (82.0)

* A multivariate logistic regression model was performed for the male gender alone. In the analysis, the adjusted odds for current smoking were 1.179 (95% CI: 0.687-2.023) with a P value of 0.551. No significant association was observed. ^†Chi-square test. ^‡Statistically significant at P<0.05. Acronyms—OR: Odds ratio, UOR: Unadjusted OR, AOR: Adjusted OR, CI: Confidence interval

The multivariate logistic regression model revealed that non-modifiable risk factors such as male gender (adjusted odds ratio [AOR]: 2.02; 95% confidence interval [CI]: 1.32–3.09), age >40 years (AOR: 2.32; 95% CI: 1.57–3.41), family history of hypertension (AOR, 1.87, 95% CI: 1.19–2.92) and modifiable risk-factors such as current alcohol consumption (AOR: 2.05; 95% CI: 1.27–3.31), high/very high perceived stress (AOR: 2.15; 95% CI: 1.28–3.62), lack of participation in stress relief activities (AOR: 2.08; 95% CI: 1.17–3.71) and overweight/obesity (AOR: 2.26; 95% CI: 1.55–3.30) were independently associated with hypertension in this study [Table 3].

Discussion

Our study intended to determine the prevalence and factors associated with hypertension in middle-aged Nagas living in urban Dimapur, Nagaland. A high prevalence of hypertension (26%) and pre-hypertension (45%) among our participants was observed. Male gender, age >40 years, family history with hypertension, current use of alcohol, high and very high perceived stress, lack of participation in stress relief activities, and overweight/obesity were independent risk factors associated with hypertension in our study.

Concurrent with our study findings, the estimates for hypertension in all regions have been steadily increasing as India is experiencing a demographic transition due to lifestyle changes and dietary habits attributed to rapid urbanization.[22,23,24] This urban phenomenon seen in large Indian cities is now percolating to smaller cities and towns where traditional communities are now exposed to a more urbanized environment. The implications of this may not be palpable at the moment, but this naive population will face the medical and economic impact of the complications of hypertension and other lifestyle diseases eventually. Nagaland also has the lowest health index among all small Indian states.[25] Eventually, the burden of complications due to hypertension will also increase, and the state’s health system will face the brunt of this emerging health issue in addition to existing difficulties due to rugged terrain, internal conflict, unsubstantial private investments, and misappropriation of funds.[26] Only a quarter of the study participants with hypertension already knew their status compared to the pooled Indian estimate of 37.6% reported by Anchala et al.[27] End organ pathology due to uncontrolled BP often starts long before symptoms surface and would have considerably progressed by the time medical care is sought. The low level of awareness is probably due to fewer screening opportunities and the lack of adequate primary health care for this community.

A salient finding in our study was that pre-hypertension prevalence was significantly higher than in other Indian studies.[23] Meshram et al.[28] have also recently reported higher estimates of pre-hypertension among women in Nagaland (36.5%) compared to other North-eastern states like Meghalaya (18.3%). People with pre-hypertension are 2 and 3.5 times more likely to develop hypertension and heart disease, respectively.[29] Early screening will ensure people are aware of their pre-hypertension status, and simple conservative interventions at this point will impact the community’s hypertension-related morbidity and mortality in the long haul.

This study identified key non-modifiable risk factors associated with hypertension in this community. Similar to another north Indian study, the male gender was an independent risk factor for hypertension.[30] Males are also more likely to develop heart disease ten years earlier and fatal complications like myocardial infarction 20 years earlier before threatening women, affecting their most productive years.[29] As corroborated by another study, we noticed nearly a two-fold increased risk for hypertension with age and family history.[30] In time, the blood vessels in the human body gradually lose pliancy with hormonal changes and contributes to the increase in BP.[31] People with hypertension in the family are also more likely to share a common environment and other potential factors (like dietary habits, exposure to smoking, etc.) that increase their risk. Since the intention to screen for hypertension in Nagaland is predominantly opportunistic or often incidental during a visit to a health care facility, implementing community-based screening programs will improve access to this community’s members.

This study identified important modifiable risk factors associated with hypertension in this community. Alcohol was independently associated with hypertension, consistent with other studies.[32,33] Despite the legal prohibitions, the prevalence of alcohol and tobacco use is still high in Nagaland.[34] Stress is another important factor associated with hypertension and is often underdocumented. Participants with high and moderately high perceived stress were nearly two times more likely to be hypertensive. A recurrent increase in BP and stimulation of the nervous system results in more significant amounts of vasoconstriction hormones contributing to elevated BP.[35] People use various coping mechanisms to combat stress. We found a two-fold increased risk for hypertension in participants who do not participate in prayer/meditation, social and community events, exercises/stretching/sports, and playing with pets. Personal spiritual practices, social participation, exercise, and other preventative measures have been documented to lower high BP.[36,37] Although limited, studies have found that spending time with pets like dogs, cats, and other animals can positively impact a person’s mood and health. Pet owners had better stress coping mechanisms than non-owners, particularly when they have higher-quality relationships with their pets.[38] More studies are required to establish a relationship between participation in the above coping styles and hypertension. Nonetheless, it can be concluded that a significant relationship does exist.[39]

An increase in BMI has been observed in the region, mainly due to changes in lifestyle and dietary habits.[40] Being overweight and obese significantly increased the odds of increased BP, which was consistent with other studies.[23,40] Increased vascular resistance in the obese and overweight increases the workload of the heart to pump blood throughout the body, thus increasing the BP. Most people living in Nagaland belong to tribal or indigenous groups. They were previously engaged in agrarian activities scattered in the hilly rural terrain of Nagaland and were predominantly involved with intense physical activity and healthy traditional diets but are now migrating to the cities. Eventually, the labor-intensive physical activities related to their previous vocation necessitated by rugged hilly terrain are replaced with sedentary jobs, and their traditional diet is replaced with non-healthy options as they accept and adopt the urban experience. Although indirect, these factors may eventually influence the mean weight gain of the community, increasing the burden of hypertension.

In this study, 26% and 45% of the participants had hypertension and pre-hypertension, respectively. Males, individuals above 40 years of age, with a family history of hypertension, current alcohol users, and overweight/obese are at a higher risk of hypertension in this community. We also identified that individuals with high and very high perceived stress and lack of participation in stress relief activities were also at a higher risk of hypertension in this community. Very few studies have reported the burden and determinants of hypertension, especially pre-hypertension, in communities in North-east India that differ socially and culturally from the rest of the country.

Hypertension is a multifaceted disease that requires a comprehensive approach. Evidence suggests that primary care and family physicians effectively detect, evaluate, manage and control hypertension in a primary care setting, preventing unnecessary spillover of patients to the few tertiary hospitals.[41,42] The role of primary care health providers, especially family physicians, becomes apparent since they are often the first point of contact. The management of hypertension requires regular follow-ups, and family physicians are best positioned as they cultivate long-term relationships with patients. Like other NCDs, the prevention and control of hypertension also depend on the individual’s commitment to consistent lifestyle modifications. Reducing the harmful use of alcohol/tobacco and improving diets, nutrition, and physical activity requires regular monitoring reinforced with constant motivation to quit or control, a role best played by the family physician. They can also detect complications before they manifest and identify secondary hypertension requiring a timely referral. So far, the system has failed to identify, treat and control hypertension which provides a unique opportunity for family physicians, the cornerstone for prevention and care, to successfully manage and prevent hypertension in this community.

Limitations

A limitation of this study was the cross-sectional design of the study, as it cannot establish causal associations between the risk factors and the outcome. To avert information bias, the investigator tried to conduct one-on-one interviews; however, this was not possible in some cases. Also, the authenticity of the morbidity stated by the family could not be ascertained since it was done verbally.

Conclusion

The burden of hypertension, especially pre-hypertension, is considerably high in this community. Efforts to increase awareness regarding hypertension and its risk factors (with emphasis on avoiding tobacco/alcohol, coping with stressors, and controlling body weight by consuming a healthy diet) through culturally appropriate methods may improve this community’s health-seeking behavior. We recommend targeted screening of males, >40 years, history of hypertension in the family, current alcohol users, and overweight/obese individuals in this community. Implementing a tailored community-based screening program with an adept referral system using trained volunteers, primarily targeting those with the aforementioned non-modifiable/modifiable risk factors, will ensure that high-risk groups are prioritized while decentralizing the screening process. Prompt efforts must be made to curtail this growing threat to avert an impending health catastrophe for this community.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

This research was conducted with internal funding support from Christian Medical College, Vellore.

Conflicts of interest

There are no conflicts of interest.