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 ::  Abstract
 :: Introduction
 :: Methodology
 :: Results
 :: Discussion
 :: Conclusion
 ::  References
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  Table of Contents     
Year : 2017  |  Volume : 63  |  Issue : 4  |  Page : 232-236

Is rule of halves still an occurrence in South India: Findings from community-based survey in a selected urban area of Puducherry

1 Department of Preventive and Social Medicine, JIPMER, Puducherry, India
2 Department of Community Medicine, PIMS, Puducherry, India
3 Department of Community Medicine, MAMC, New Delhi, India

Date of Submission27-Mar-2017
Date of Decision04-May-2017
Date of Acceptance22-May-2017
Date of Web Publication11-Oct-2017

Correspondence Address:
S S Kar
Department of Preventive and Social Medicine, JIPMER, Puducherry
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jpgm.JPGM_164_17

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 :: Abstract 

Background: The objective of the present study was to assess the applicability of the rule of halves in an urban population of Puducherry, South India. We also aimed to find the correlates associated with undiagnosed hypertension to facilitate targeted screening. Methodology: We derive our observation from a community-based cross-sectional study conducted using the World Health Organization STEPwise approach to surveillance in urban slum of Puducherry during 2014–15. Blood pressure (BP) was measured for all the study subjects (n = 2399), and the subjects were classified as hypertensive using Joint National Committee 8 criteria, systolic BP (SBP) ≥140 mm Hg and/or diastolic BP (DBP) ≥90 mmHg and/or known hypertensives and/or treatment with antihypertensive drugs. Controlled hypertension was defined as SBP <140 mmHg and DBP <90 mmHg. Results: Of 2399, 799 (33.3%; 95% confidence interval [CI]: 31.4%–35.2%) adults were found to have raised BP by any means (known and unknown hypertensives). Of the 799, 367 (15.3%; 95%CI: 13.9%–16.8%) of study participants were known hypertensives. Of the known hypertensives, 74.7% (274/367) were put on treatment (drugs and or lifestyle modification), and 80% (218/274) were on regular treatment. Higher proportions of men were found to have undiagnosed hypertension compared to women (26.1 vs. 19.8%, P < 0.001). Similarly, adult from below poverty line (23.8 vs. 20%, P < 0.001), unskilled laborer (26.6 vs. 20%, P < 0.001), and literacy less than middle school (12.3 vs. 23%, P < 0.001) had more undiagnosed hypertension. Conclusion: In the selected urban area of Puducherry around one-third of the adult populations are having hypertension, including the 54% of undiagnosed hypertension. Adults from the vulnerable subgroups such as lower level of literacy, below poverty line, and unskilled work are found to have higher proportions of undiagnosed hypertension.

Keywords: Community-based survey, hypertension, rule.of.halves

How to cite this article:
Kar S S, Kalaiselvi S, Archana R, Saya G K, Premarajan K C. Is rule of halves still an occurrence in South India: Findings from community-based survey in a selected urban area of Puducherry. J Postgrad Med 2017;63:232-6

How to cite this URL:
Kar S S, Kalaiselvi S, Archana R, Saya G K, Premarajan K C. Is rule of halves still an occurrence in South India: Findings from community-based survey in a selected urban area of Puducherry. J Postgrad Med [serial online] 2017 [cited 2023 Sep 29];63:232-6. Available from:

 :: Introduction Top

Hypertension, commonly referred to as “high blood pressure (BP)” is a serious medical condition and happens when blood flows through the blood vessels with a force greater than normal.[1] Hypertension is one of the most important preventable contributors to disease and death worldwide, leading to myocardial infarction, stroke, and renal failure when it is not detected early and treated appropriately. Around one-third of the adult population in SEA have elevated BP with nearly 1.5 million deaths (9.4% of total deaths) attributable to hypertension annually.[2]

Eighth Joint National Committee (JNC 8) recommends evidence-based guidelines for treatment initiation and goals for BP control in various age groups and also with comorbid conditions.[3] However, most of the hypertensives are unaware of their hypertensive status, most of those who are diagnosed are untreated. Of those who are treated, most of them are inadequately treated and do not achieve the BP control goal. This phenomena has been described as the “rule of halves” and was coined in 1970s in the America,[4] was reported in Scotland in the 1990s,[5] and has been reported previously from some parts of India.[6],[7] Early detection through surveillance, increasing the access to primary care for hypertension is proposed to be an urgent measure in many international agendas, including the recent United Nations high-level meeting on noncommunicable diseases (NCDs).[8] In India also, recently, major thrust is being given to early diagnosis and treatment for NCD under the realm of National Programme on Prevention and Control of Cancer, Diabetes, Cardio Vascular Disease and Stroke (NPCDCS).[9] The trend in awareness, prevalence, treatment, and control related to hypertension after the roll out of NPCDCS is not being tested.

Because it is important to audit control of BP in a subnational level with high coronary mortality and stroke mortality,[10] we explored to test this concept in our population from the data of a community-based survey to see whether the rule of halves still applies in the selected urban population of Puducherry, south India. We also aimed to find the correlates associated with undiagnosed hypertension to facilitate targeted screening.

 :: Methodology Top

A community-based survey using the World Health Organization (WHO) STEPwise approach to surveillance (STEPS) was conducted in urban slum of Puducherry in 2014–15.[11] The study area has four urban census enumeration blocks covering a population of 9500 which are linked under the care of tertiary teaching care institute as urban health training center. All adults aged 18 years and more living in these four enumeration blocks for more than 6 months constituted the study target population. Initially, from the recent updated census of 2014, household with adults aged 18 years and above were extracted. These houses were visited by the trained personnel during the survey. During the house-to-house survey after obtaining informed consent, information was verified regarding the number of adults aged 18 years or more living in that household. If eligible adults are present, following information was obtained using WHOs STEPS survey tool: sociodemographic characteristics, risk factors related to NCD such as tobacco and alcohol use, patterns of fruit and vegetable, salt and oil consumption, history of hypertension diagnosed in the past, family history of hypertension, details of treatment for hypertension, and associated comorbidities. In case, eligible adults are not available during the first visit, further two more visits were made to meet the eligible individuals in their convenient time. Regardless of the self-reported status of hypertension, BP of all eligible participants was measured using standardized automatic electronic BP monitors (Omron BP785 10 Series). Over 10-min interval, BP was measured again, and the average of these two measures was considered for classification of hypertension as recommended by JNC 8 guideline.[3] In case, if the individual was reported by any health-care provider to have hypertension or they reported under antihypertensive medications, it was classified as diagnosed hypertension. Among these adults with diagnosed hypertension and on treatment, average BP obtained from two readings was classified as optimum BP control and BP not under controlled limit using JNC 8 criteria. Individuals are considered to be on treatment if any they were diagnosed to have hypertension by any health-care provider and reported to follow any of the following methods: antihypertensive medication, treatment under alternate systems of medicine such as AYUSH, lifestyle modifications such as change in the diet, regular physical activity, weight reduction, and quit from alcohol and tobacco. This study was approved by the Institute Ethics Committee.

Single data entry operator did the data entry. However, the investigators randomly checked 20% of the dataset for accuracy, and after the field data collection, 10% of the forms were checked for completeness. Data were analyzed using EpiData analysis software.[12] State of hypertension, awareness of hypertension status, treatment and control for the same is summarized as proportions with 95% confidence interval (CI). Different sociodemographic correlates were identified using Chi-square test. P < 0.05 was considered statistically significant.

 :: Results Top

Burden of undiagnosed hypertension

There were totally 2399 adults who were 18 years or more had participated in the STEPS survey. Of the 2399, 367 (15.3%–95%CI: 13.9%–16.8%) of them has reported that they have been informed as a hypertensive by health-care providers (known hypertensives). Of the rest 2032 adults, 1847 had their BP checked during the survey with an overall response rate of 94%. Of 1847 screened, 432 (21.3%) found to have BP in the hypertension range (either systolic BP ≥ 140 mmHg or diastolic BP ≥90 mmHg or both) (unknown/occult hypertensives). Thus, totally 799 (33.3%; 95%CI: 31.4%–35.2%) adults were found to have raised BP by any means. This house-to-house survey had facilitated to identify 54.1% (432/799) of undermined occult hypertensive cases in the community [Figure 1].
Figure 1: Distribution of known and unknown hypertensives in urban Puducherry, 2014–15

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Treatment seeking among diagnosed hypertension patients

Of the 367 (46%) adults who were already diagnosed as hypertension around 74.7% (274/367) were put on treatment by either antihypertensive drugs or by lifestyle modifications. In this subset, only 80% (218/274) had reported that they were regularly taking drugs and going for regular medical check-up as per the physician instructions. The subgroup analysis considering gender, age group, and family history was provided in [Figure 2] and [Table 1]. Treatment seeking was lesser in selected subgroups such as illiterate and semi-skilled workers. Similarly, higher proportions of adult men, unskilled laborers, and illiterates had poor control of BP compared to adult women, professionals, and postgraduates, respectively (P < 0.05).
Figure 2: Distribution of hypertension status based on gender, age, and family history

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Table 1: Burden of diagnosed and undiagnosed hypertension by sociodemographic characteristics from the World Health Organization STEPwise approach to surveillance survey in urban slum of Puducherry 2014-2015

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Correlates associated with undiagnosed hypertension

Higher proportions of men were found to have undiagnosed hypertension compared to women (26.1 vs. 19.8%, P < 0.001). Similarly, adult from below poverty line (23.8 vs. 20%), unskilled laborer (26.6 vs. 20%), and literacy less than middle school (12.3 vs. 23%) had more undiagnosed hypertension compared to above poverty line, unemployed, and literacy high school or more respectively. There was an increasing trend observed with age and undiagnosed hypertension [Table 1].

 :: Discussion Top

The major problem in achieving better control of hypertension in a community is the silent and asymptomatic nature of the disease. Ignorance of the general population to the nature of elevated BP, its morbid effects, and the methods of maintaining its control is widespread and contributes to the large percentage of undetected and untreated hypertensive subjects in a community.

This community-based study involving house-to-house BP measurement by a trained data collector provides many opportunities to understand the dynamics of hypertension control in Puducherry - a relatively better health care system in India. Although more than half (54%) of the hypertensive population were unaware about the condition, it was observed that about two-third (75%) were receiving some form of medical care (medicine and/or lifestyle measures) and 80% of them were on regular medication.

Across the different global settings, undiagnosed hypertension was more commonly observed in developing countries (50%–65%) compared to developed countries (25%–50%). Similarly, the proportions of hypertensives started on regular treatment also more in developed countries (70%–85%) compared to developing nations (29%–50%).[2],[7],[13],[14],[15],[16],[17],[18],[19],[20]

The Chennai Urban Population Studies (CUPS) in 2003 reported that only 37.3% were known hypertensives, among these known hypertensives, only 50% were under any kind of antihypertensive therapy, and of these, only 40% had BP under control.[6] Our study results were comparatively better than the CUPS finding and may be because of the year, in which the study was conducted (2003 vs. 2014–15). During this period, a lot of initiatives were undertaken by Ministry of Health, Government of India, in the form of a launching of NPCDCS in 2010. A lot of capacity building activities were undertaken nationwide and through state government to prevent and control cardiovascular diseases and management of chronic NCDs, especially cancer, diabetes, CVDs and stroke through early diagnosis, treatment, and follow-up through setting up of NCD clinics were the major objectives envisaged.[9]

Another study conducted in the rural village of Aligarh district of Uttar Pradesh of India reported the awareness regarding hypertension to be 40.3% among adults of more than 40 years.[7] These two studies from south and north India had concluded that rule of halves is still prevalent in India scenario; however, our study findings are similar as far as the awareness regarding hypertension goes. We found that once a person who is hypertensive comes to the fold of health-care system in Puducherry, on treatment and compliance to treatment increases significantly (at least two-thirds). This indicates that Puducherry has a good mechanism to follow-up known cases, but our performance is similar to the reported studies (around half) pertaining identifying the new/occult cases.

In this study, adults being a male, increasing age, illiterate, unskilled work, below poverty line, and no family members affected due to hypertension were more likely to be associated with undiagnosed hypertension. This could be due to the influence of synergistic factors such as ignorance, lack of affordability, and fear of losing wages. The paradox on lesser undiagnosed hypertension found among adults with family history of hypertension could be the reflection of high-risk opportunistic screening conducted for family members of the affected individuals.

This study has following strengths. In this study, house-to-house survey was conducted preferably within their convenient time for participation. Hence, it reflects the accurate burden on hypertension. In this study, without any sampling, large number of adults were included which would minimize the sampling error. This study used the comprehensive tool as suggested by WHO STEPS approach.

 :: Conclusion Top

Although the rule of halves phenomena is still applicable in our set up, we observed that once study participants know regarding hypertension, regular intake of medication increases substantially. It is suggested that community screening programs combined with simplified diagnostic evaluation, intense patient education, and follow-up may greatly increase the percentages under continuous treatment and control.


Authors acknowledge the role of Dr. Vinod Kumar Kalidass and field investigators Mr. Abiraman, and Mrs. Nithya in data collection.

Financial support and sponsorship

The study was supported by the intramural research grant of JIPMER, Puducherry.

Conflicts of interest

There are no conflicts of interest.

 :: References Top

Hypertension – National Library of Medicine – PubMed Health. Available from: [Last cited on 2017 Mar 11].  Back to cited text no. 1
Castillo R. SSA 03-1 Prevalence and management of hypertension in Southeast Asia. J Hypertens 2016;34 Suppl 1:e4.  Back to cited text no. 2
Hernandez-Vila E. A review of the JNC 8 blood pressure guideline. Tex Heart Inst J 2015;42:226-8.  Back to cited text no. 3
Wilber JA. The problem of undetected and untreated hypertension in the community. Bull N Y Acad Med 1973;49:510-20.  Back to cited text no. 4
Smith WC, Lee AJ, Crombie IK, Tunstall-Pedoe H. Control of blood pressure in Scotland: The rule of halves. BMJ 1990;300:981-3.  Back to cited text no. 5
Deepa R, Shanthirani CS, Pradeepa R, Mohan V. Is the 'rule of halves' in hypertension still valid? – Evidence from the Chennai Urban population study. J Assoc Physicians India 2003;51:153-7.  Back to cited text no. 6
Faizi N, Ahmad A, Khalique N, Shah MS, Khan MS, Maroof M. Existence of rule of halves in hypertension: An exploratory analysis in an Indian village. Mater Sociomed 2016;28:95-8.  Back to cited text no. 7
WHO. United Nations High-Level Meeting on Noncommunicable Disease Prevention and Control. New York: WHO; 2015. Available from: [Last cited on 2017 Mar 12].  Back to cited text no. 8
National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke (NPCDCS) Programme Background. Available from: [Last cited on 2017 Mar 11].  Back to cited text no. 9
WHO. Global Status Report on NCDs. Geneva: WHO; 2015. Available from: [Last cited on 2017 Mar 11].  Back to cited text no. 10
WHO. STEPwise Approach to Surveillance (STEPS). Geneva: WHO; 2015. Available from: [Last cited on 2017 Mar 11].  Back to cited text no. 11
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Banerjee S, Mukherjee TK, Basu S. Prevalence, awareness, and control of hypertension in the slums of Kolkata. Indian Heart J 2016;68:286-94.  Back to cited text no. 13
Hypertension Study Group. Prevalence, awareness, treatment and control of hypertension among the elderly in Bangladesh and India: A multicentre study. Bull World Health Organ 2001;79:490-500.  Back to cited text no. 14
Irazola VE, Gutierrez L, Bloomfield G, Carrillo-Larco RM, Dorairaj P, Gaziano T, et al. Hypertension prevalence, awareness, treatment, and control in selected LMIC communities: Results from the NHLBI/UHG network of centers of excellence for chronic diseases. Glob Heart 2016;11:47-59.  Back to cited text no. 15
Jo I, Ahn Y, Lee J, Shin KR, Lee HK, Shin C. Prevalence, awareness, treatment, control and risk factors of hypertension in Korea: The Ansan study. J Hypertens 2001;19:1523-32.  Back to cited text no. 16
Joffres MR, Ghadirian P, Fodor JG, Petrasovits A, Chockalingam A, Hamet P. Awareness, treatment, and control of hypertension in Canada. Am J Hypertens 1997;10 (10 Pt 1):1097-102.  Back to cited text no. 17
Lee HS, Park YM, Kwon HS, Lee JH, Park YJ, Lim SY, et al. Prevalence, awareness, treatment, and control of hypertension among people over 40 years old in a rural area of South Korea: The Chungju Metabolic Disease Cohort (CMC) Study. Clin Exp Hypertens 2010;32:166-78.  Back to cited text no. 18
Perez-Fernandez R, Mariño AF, Cadarso-Suarez C, Botana MA, Tome MA, Solache I, et al. Prevalence, awareness, treatment and control of hypertension in Galicia (Spain) and association with related diseases. J Hum Hypertens 2007;21:366-73.  Back to cited text no. 19
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  [Figure 1], [Figure 2]

  [Table 1]

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