|Year : 2016 | Volume
| Issue : 1 | Page : 51-56
Application of “rule of halves” in an urban adult population, Himachal Pradesh: A study from North India
Kanica Kaushal, Anjali Mahajan, SR Mazta
Department of Community Medicine, IG Medical College, Shimla, Himachal Pradesh, India
|Date of Web Publication||13-Jan-2016|
Department of Community Medicine, IG Medical College, Shimla - 171 001, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Introduction: Approximately half of most common chronic disorders are undetected that half of those detected are not treated, and that half of those treated are not controlled. This is true of hypertension as well: The “rule of halves.” However, the relevance of this is being questioned now.
Objective: The aim of the present study was to assess the applicability of the rule of halves in an urban adult population in North India to evaluate its relevance in establishing levels of awareness, thus control of hypertension in general population.
Materials and Methods: A cross-sectional community survey was done to include 187 men and 213 women aged >20 years of age in Shimla city, Himachal Pradesh. Hypertension was assessed using standardized recording, structured schedule on diagnosis and antihypertensive drug treatment according to The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure.
Results: The data were expressed in percentages, and Chi-square test was used to list the significance of sociodemographic factors. Of the total 400 participates, 208 individuals (52%) had hypertension. The prevalence of self-reported hypertension was 35% (139/400). However, the prevalence of self-reported hypertension (aware) among diagnosed patients of hypertension on examination by investigator was 139/208.
Conclusion: The relevance of “rule of halves” in establishing the levels of awareness and control of hypertension is undervalued and cannot be undermined especially in context of developing countries.
Keywords: Hypertension, population, rule of halves, urban
|How to cite this article:|
Kaushal K, Mahajan A, Mazta S R. Application of “rule of halves” in an urban adult population, Himachal Pradesh: A study from North India. Nig J Cardiol 2016;13:51-6
|How to cite this URL:|
Kaushal K, Mahajan A, Mazta S R. Application of “rule of halves” in an urban adult population, Himachal Pradesh: A study from North India. Nig J Cardiol [serial online] 2016 [cited 2019 Dec 13];13:51-6. Available from: http://www.nigjcardiol.org/text.asp?2016/13/1/51/165165
| Introduction|| |
Cardiovascular diseases (CVD) are the leading cause of death and disability in low-income countries including India. In India, hypertension is the leading risk and is estimated to attribute for 10% of all deaths. Prevalence has risen dramatically over the past three decades. The number of hypertensive individuals is anticipated to nearly double from 2000 to 2025. One of the factors usually associated with increasing burden of noncommunicable diseases like CVD's is inability to obtain preventive services. This is true of hypertension as well. In spite of the efforts, prevention, early detection and treatment, control of hypertension is still suboptimal and unsatisfactory not only in developing countries like India but also in well-developed countries.
A review of medical literature suggests that approximately half of patients with raised blood pressure (BP) are undetected that half of those detected are not treated, and that half of those treated are not controlled (rule of halves). Studies across populations in developed world have shown that awareness and management of high BP levels are far from optimal., The studies speak of rule of halves as not being valid for screening and treatment of hypertension in industrialized countries; however, it might still be valid for developing countries., The disagreement on the validity of this rule serves as crude reminder that BP control is far from optimal.
Keeping this in view, a study was planned to understand the relevance of “rule of halves” in establishing the levels of awareness and control of hypertension.
The aim of the present study was to assess the applicability of the rule of halves in an urban adult population catered by Urban Health Training Center (UHTC), IGMC Shimla to evaluate its relevance in establishing levels of awareness, thus control of hypertension in general population.
| Materials and Methods|| |
A community based cross-sectional survey was done at Boileauganj, Shimla; Himachal Pradesh, a state in Northern India. UHTC Boileauganj provides outpatient facilities to the area falling under urban training facility for teaching and training of undergraduate and postgraduate students in Department of Community Medicine, IGMC Shimla. Boileauganj has a total population of 8205 individuals living in 2243 households as per census 2011.
A total of 400 participants were included in the study consisting of comprising of 187 men and 213 women aged >20 years. All the individuals who were more than 20 years old were screened for high BP.
Taking the total population of Municipal Corporation Shimla as 1, 70,000 as per 2011 census, hypothesized frequency of awareness levels of hypertension amongst residents of Shimla city as 50%, confidence limits as 5% of 100 and design effect of 1, the sample size calculated for the study using the formula n = [(DEFF × Np (1 − p)]/[(d 2/Z 21-α/2 × (N − 1) +p × (1 − p)] came out to be 384. Therefore, 400 participants were included for the study.
In the first stage, the households were selected by systematic random sampling. The household constituted the primary sampling unit. The whole study area was mapped, and all the main roads were identified. UHTC Boileauganj was taken as the starting point for the purpose of this study. Four directions were identified, and one direction was selected randomly. The main road leading in that direction was approached first, and the first house reached was considered as the first household for the study. Thereafter every third household was selected and visited for the purpose of the study. Once the boundary of population served by Boileauganj in that direction was reached; the adjacent direction starting from UHTC was approached for the same.
In the second stage, a single eligible participant was chosen from the selected household that formed the secondary sampling unit. An enquiry regarding an eligible participant (based on the inclusion criteria, i.e., individuals more than 20 years of age) was made in the selected household. For households with only one eligible participant that person became the designated participant and was included in the study. In case of more than one eligible participant in the selected household, lottery method was used to select a single participant by simple random sampling.
The study was verbally explained to the participant, and adequate opportunities were given for discussion of any of their questions. A written description of the study was shown to the participant for obtaining his/her consent. If the selected participant refuses to give consent for the study, the next eligible participant was selected from that household by repeating the selection process.
The research was carried out in two phases: A screening phase and an evaluation phase.
The participants were screened for presence or absence of BP and were classified as hypertensive or nonhypertensive as per the criteria and definitions used in the study. BP was recorded in the sitting position in the right arm to the nearest 2 mmHg with a mercury sphygmomanometer. Two readings were taken 5 min apart, and the mean of the two was taken as the BP. The first and the fifth Korotkoff sounds were used to define systolic BP (SBP) and diastolic BP (DBP), respectively. Variation in BP measurements was minimized by (a) ensuring 10 min rest before BP recording, (b) using standard cuffs for adults fitted with standard mercury sphygmomanometer, (c) placing the stethoscope bell lightly over the pulsatile brachial artery and (d) the same observer recording the BP.
After the screening phase, all the study participants were evaluated for the relevance of the rule of halves in the study population by administering a structured schedule. The schedule had questions on sociodemography of the participants. A question on awareness about their BP was also a part of the schedule.
The process was conducted in a manner and location that ensures participant privacy and after obtaining the participant's consent to participate.
Definitions and diagnostic criteria
Hypertension was diagnosed if subjects included in the study were known hypertensive's (as per records, i.e., with “noncommunicable diseases” registers being maintained at UHTC Boileauganj and patients personal records) and were under antihypertensive medication and/or had SBP of 140 mmHg or greater and/or DBP of 90 mmHg or greater, without a co-morbid condition like diabetes or chronic kidney disease. Controlled hypertension was defined as those who were on treatment and had a BP of <140/90 mmHg or a BP of 130/80 in case of those with co-morbidity like diabetes or chronic kidney disease.
Statistical analysis was performed using the CDC Open Epi version 3.03 and IBM SPSS version 17 package. A P ≤ 0.05 was taken as statistically significant. The data were expressed in percentages, and Chi-square test was used to list the significance of sociodemographic factors. Fischer exact test was applied where more than 20% of cells had expected value <5.
Free and informed consent was obtained from the study subjects. Confidentiality of information was maintained in accordance with the principles embodied in the Declaration of Helsinki and the International Guidelines for Ethical Review of Epidemiological Studies.
| Results|| |
Totally, 400 participants comprising of 187 men and 213 women aged >20 years were recruited for this study. Of the total 400 participants, 208 individuals (208/400) that is 52% had hypertension.
The prevalence of self-reported hypertension among patients reporting to UHTC was 35% (139/400). However, the prevalence of self-reported hypertension among diagnosed patients of hypertension (aware) on examination by investigator was (139/208; 67%). Of these 139 aware hypertensive subjects, 88% (123/139) were under treatment for hypertension.
Of those 123 treated, 43 got adequately treated that is 35% (43/123) got their BP under control.
Of these 139 individuals (aware and treated), 31% (43/139) had BP under control (adequately treated) as per definitions. Of 139 aware hypertensive, 16 patients that is 12% (16/139) were not receiving any kind of drug treatment at all [Figure 1].
|Figure 1: Pictorial description of rule of halves as applied to urban adult population of Shimla|
Click here to view
The sociodemographic influences on awareness of hypertension showed that participant's occupation significantly affect the awareness level of hypertension (χ2 = 16.72, df = 2, P = 0.0002). Those women who were the homemakers had the maximum awareness about hypertension followed by those who were either retired or unemployed or were students (nonworking class). But it was seen that the increase in the number of years of education (χ2 = 0.02, df = 2, P = 0.98) and belonging to a certain type of family (χ2 = 4.85, df = 2, P = 0.0884) does not seem to have any significant effect on the level of awareness regarding hypertension [Table 1].
|Table 1: Sociodemographic influences on “awareness” of hypertension in study population|
Click here to view
A similar analysis of sociodemographic influences on adequacy of treatment of hypertension shows that those living in joint family are more likely to get adequately treated for hypertension than those living in nuclear families (exact test, χ2 = 12.087, df = 2, P = 0.002). On the other hand, we did not find any significant difference in either the occupational status of the participant (χ2 = 0.97, df = 2, P = 0.61) or his/her level of education (χ2 = 0.805, df = 2, P = 0.66) toward adequacy of treatment for hypertension [Table 2].
|Table 2: Sociodemographic influences on treatment of hypertension in study population|
Click here to view
[Figure 1] gives the pictorial description of the rule of halves as applied to the study population of Boileauganj, Shimla.
The influence of level of education on awareness and medication compliance in hypertensive subjects is complex, as other factors such as cultural beliefs; religion, peer influences and personality do modify the inclination of subjects to comply with medications.
| Discussion|| |
The 1992 Victoria Declaration on Heart Health has advised adoption of a public health approach for the prevention and control of CVD by adopting four cornerstone approach to heart health by controlling risk factors of hypertension.
The focus of public health and prevention in particular with regard to CVD like hypertension is early detection and drug treatment (antihypertensive) of patients with high BP. The key to early detection will always be the level of awareness among the general population about hypertension. No doubt, with the efforts of national and international health organizations, the awareness of hypertension has increased in the last decade, particularly in industrialized nations., However, despite efforts, awareness and management of high BP levels are far from optimal., The famous rule of halves comprehensively brought into focus our level of awareness and management of hypertension in past. The rule of halves has remained, for long, the standard referral point on the level of awareness and treatment (adequate or inadequate) in the general population. However, the relevance of this rule needs evaluation keeping in view the debate going on to prove its validity. Its evaluation works as an efficient surrogate for the assessment of awareness and management of high BP. Its evaluation also reflects on our inability to establish better referral points for establishing awareness levels in the general population because studies in past have reflected differently on awareness about hypertension.
A study by Deepa et al. found that only one-third (37.3%) of the hypertensive knew about their condition. About 50% of known hypertensive subjects were treated, and 40% of the treated cases were controlled. Thus, only 7.5% of the total hypertensive subjects in this study were under control despite 18.6% being under treatment. Whereas our study showed higher figure of 67% of hypertensive's who knew about their condition. Of that, 88.4% of the known hypertensive subjects were treated but only 35% were controlled. But in contrast to the findings in our study, both the awareness and treatment of hypertension among the higher social class were significantly higher compared to lower income group (P < 0.05).
In a study by Mohan et al., among the known hypertensive subjects, 70.8% were under treatment for hypertension; however, only 45.9% had BP under control which represents 15.4% of the total hypertensive group.
In a study conducted in South India, only 37.3% of the total subjects with hypertension were aware that they had hypertension. However, our findings on the awareness on hypertension report with higher figures of 67%. Further our findings are also higher than that reported in a study from Northern India (22.05%). In spite of the numbers reported being higher than studies conducted previously in India, we may not fully agree with the rule of halves concept for hypertension. The study per se reflects on this disagreement.
Interestingly our study also reports a higher awareness than a study conducted in the Northern China (25%). Despite increased rates of BP–lowering treatment, few have their hypertension effectively controlled. Among those individuals receiving treatment, adequate control of BP (140/90 mmHg) was achieved in 24% only.
The rule of halves of hypertension was put forth based on cross-sectional community-based study in Scotland in the year 1990. The report itself has spoken on the validity of this rule for developing countries and that the success rate in case detection, treatment and control could all be improved. This study concluded that the situation is better in women than in men with the poorest control of hypertension in men in the younger age groups.
In a study by Rocella et al. to study 20-year trend data in changes in hypertension awareness, treatment, and control rates in USA, public knowledge, awareness, treatment, and control of high BP have changed remarkably. The authors have agreed that without a control group it is always difficult to attribute causality; however, the improving levels are remarkably large and consistent.
The present study found that two-third (67%) of the hypertensive were aware about their condition, which is in disagreement with the rule of halves. This could be because almost one full generation of the population has passed on after this concept was developed. This could also be because of the awareness created by initiation of National Programs Focusing on noncommunicable diseases like National Program for prevention and control of diabetes, CVD and stroke (NPCDCS) where awareness generation is a key component. The implementation of NPCDCS could also be the reason for the fact that 88% of aware hypertensive subjects are being treated with medication.
However, the fact that only 35% of treated cases are controlled is a cause of concern. It is this group of population which needs to be targeted to ensure better management of hypertension. Therefore, the rule of halves as suggestive of awareness and treatment probably needs to be split into individualized areas of awareness and treatment and then targeted as such.
The results in our study report of a much better awareness and control of hypertension than from a similar study conducted in South India. The reasons for the same could lie in the strong public health sector in Himachal Pradesh. Herein again, the universality of the rule of halves will be tested. A strong public health infrastructure should be used to build a more targeted approach.
Studies in past have reflected on the importance of various sociodemographic factors influencing awareness. The present study points to a similarity in levels of awareness and treatment across different sociodemographic parameters. Therefore, probably interventions with broad-based public health approach may be the key.
| Limitations|| |
As it was a cross-sectional study (1-time study), the patients were not followed up, and it was just the snapshot of awareness and adequacy of treatment of hypertension in the community. Therefore inherent to the study design, the cause-effect relationship could not be ascertained.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Gersh BJ, Sliwa K, Mayosi BM, Yusuf S. Novel therapeutic concepts: The epidemic of cardiovascular disease in the developing world: Global implications. Eur Heart J 2010;31:642-8.
Mohan S, Campbell N, Chockalingam A. Time to effectively address hypertension in India. Indian J Med Res 2013;137:627-31.
Gupta R, Guptha S, Joshi R, Xavier D. Translating evidence into policy for cardiovascular disease control in India. Health Res Policy Syst 2011;9:8.
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.
Hart JT. Rule of halves: Implications of increasing diagnosis and reducing dropout for future workload and prescribing costs in primary care. Br J Gen Pract 1992;42:116-9.
Marques-Vidal P, Tuomilehto J. Hypertension awareness, treatment and control in the community: Is the 'rule of halves' still valid? J Hum Hypertens 1997;11:213-20.
Awobusuyi J, Adebola A, Ajose F. Prevalence and socio-demographic profile of hypertensive patients in a Nigerian general out-patients' department. Internet J Third World Med 2012;10:1.
Burt VL, Cutler JA, Higgins M, Horan MJ, Labarthe D, Whelton P, et al.
Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the health examination surveys, 1960 to 1991. Hypertension 1995;26:60-9.
Chockalingam A, Abbott D, Bass M, Battista R, Cameron R, de Champlain J, et al.
Recommendations of the Canadian Consensus conference on non-pharmacological approaches to the management of high blood pressure, Mar 21-23, 1989, Halifax, Nova Scotia. CMAJ 1990;142:1397-409.
Mohan V, Deepa M, Farooq S, Datta M, Deepa R. Prevalence, awareness and control of hypertension in Chennai – The Chennai Urban Rural Epidemiology Study (CURES-52). J Assoc Physicians India 2007;55:326-32.
Gupta AK, Ahluwalia SK, Negi PC, Sood RK, Gupta BP, Dhadwal D. Awareness of hypertension among a North Indian population. J Indian Med Assoc 1998;96:298-9, 311.
Tao S, Wu X, Duan X, Fang W, Hao J, Fan D, et al.
Hypertension prevalence and status of awareness, treatment and control in China. Chin Med J (Engl) 1995;108:483-9.
Smith WC, Lee AJ, Crombie IK, Tunstall-Pedoe H. Control of blood pressure in Scotland: The rule of halves. BMJ 1990;300:981-3.
Rocella EJ, Burt V, Horan MJ, Cutler J. Changes in hypertension awareness, treatment, and control rates 20-year trend data. Ann Epidemiol 1993;3:547-9.
National Programme for Prevention and Control of Diabetes. Cardiovascular diseases and stroke. In: Park K, editor. Textbook of Preventive and Social Medicine. 21st
ed. Jabalpur: Banarsidas Bhanot Publishers; 2014. p. 417.
[Table 1], [Table 2]