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Abstract
Objectives To determine levels of cardiovascular disease (CVD) prevention and to model the potential impact of improved prevention strategies for a large rural Indian region.
Design A cross-sectional study with modelling of coronary heart disease (CHD) events over 10 years.
Setting Rural Andhra Pradesh, India.
Participants A stratified random sample of 1079 adults 30 years and older.
Main outcome measures Proportion on medical and behavioural treatments for prevention of CVD; estimated number of CHD events using a locally recalibrated Framingham risk equation.
Results Among the 3.5% (95% CI 2.1% to 4.9%) with existing CVD, 49.3% (95% CI 28.8% to 69.8%) were on blood pressure (BP)-lowering medication, 4.7% (95% CI 0 to 10.4%) were on cholesterol-lowering medication, 24.6% (95% CI 9% to 40.3%) had increased exercise and 26.9% (95% CI 2.6% to 51.1%) attempted to quit smoking. Among the 7.6% (95% CI 6.2% to 8.9%) with a high global CHD risk (>20% over 10 years), 29.5% (95% CI 19.5 to 39.5%) were on BP-lowering medication, 2.8% (95% CI 0 to 6.7%) were on cholesterol-lowering medication, 19.4% (95% CI 10.9% to 28%) had increased exercise and 24.8% (95% CI 15.8% to 33.8%) attempted to quit smoking. If confirmed drug therapies were provided to all individuals at high risk there would be a 28% reduction in cardiovascular events over 10 years at an approximate annual treatment cost of US$533 per event avoided.
Conclusions There are serious deficiencies in CVD prevention in rural areas of India. Addressing these with simple confirmed drug treatments could produce a large reduction in the future cardiovascular burden in India.
- Epidemiology
- public health
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Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide.1 Historically, it has been more common in high-income countries. However, in developing low and middle-income countries, the adoption of western lifestyles has led to an increase in non-communicable diseases, such as CVD.2 It is estimated that more than 80% of deaths due to CVD now occur in low and middle-income countries and this is expected to rise further.3
In India, CVD is now the leading cause of mortality.2 Age of onset is lower than in high-income countries,4 and the increasing incidence among adults of working age poses a threat to economic development.5 To date, most studies conducted in India have focused on urban populations; however, 70% of the Indian population live in rural areas,6 where poverty and poor education are common. These areas are starting to undergo economic transition,7 and recent studies from the selected areas indicate that CVD is now the leading cause of death in rural areas and there are high levels of cardiovascular risk factors including diabetes, hypertension, smoking and obesity.8–12A sharp increase in the overall burden of CVD can only be avoided if effective preventive strategies are implemented as a matter of urgency.
Targeted treatment of individuals with high overall cardiovascular risk is more effective than treating individual risk factors and is more cost-efficient.13 14 The implementation of global risk strategies in resource-poor environments is therefore likely to be the best way to maximise scarce resources.15 There is, however, currently a paucity of data to inform health policy in rural India. The aims of our study were to determine the level of primary and secondary preventive treatments of CVD and smoking, weight, exercise and dietary modification in a region of rural India and to model the impact of improved preventive strategies that utilise an absolute risk-based approach for this region.
Methods
Data sources and study population
In 2005, a cross-sectional study was conducted among a stratified random sample of adults who were 30 years or older and resident in 20 villages (total population 34 533). The study was approved by the ethics committees of the CARE Hospital, Hyderbad in India, and the University of Sydney in Australia. The sample was selected to be representative of the rural populations living in east and west Godavari in Andhra Pradesh, on the south-eastern coast of India.16 17 The villages were randomly selected from a list of 88 for which community leaders consented to participate and the Byrraju Foundation, a local non-governmental organisation, had census data available, with proportionate sampling according to population size, region and distance from the regional centre. Residents of the eligible villages were also stratified by age (30–39, 40–49, 50–59 and ≥60 years) and sex. Equal numbers of individuals were selected randomly from each stratum and invited to participate. Of the 5627 individuals contacted, 4535 (81%) participated in the study. Data were obtained from all participants by means of a questionnaire and physical examination.16 17 One in four participants were selected randomly from each age–sex stratum and were invited to provide a venous blood sample and 1079 (95%) complied. Information on screening, prevalent disease, knowledge and behavioural modification was based on self-report. The global coronary heart disease (CHD) risk for each participant was calculated using a locally recalibrated Framingham equation. The method used to derive this has been reported in detail previously.18 High global risk was defined as a greater than 20% risk of a fatal or non-fatal CHD event over 10 years, moderate risk as 10–20% and low risk as less than 10%.19
Definitions
Diabetes was defined as fasting plasma glucose 7.0 mmol/l or greater or a previous diagnosis of diabetes. Hypertension was defined as a mean of two systolic blood pressures of 140 mm Hg or greater and/or a mean diastolic blood pressure of 90 mm Hg or greater and/or treatment with blood pressure-lowering medication. Established CVD was defined as a self-report of a medical diagnosis of heart attack or stroke.
Statistical analyses
Baseline information on risk factors was expressed as frequencies and percentages for categorical data, and means and standard errors for continuous data. Differences between subgroups were tested using χ2 tests and t tests, respectively. t Tests for trend were used to examine patterns across risk categories.
Each age–sex stratum was weighted to ensure that the risk factor data for participants were representative of the total eligible population (n=34 532) resident in the 20 villages. The weights used in the analyses were derived from the population (from local census data) to sample size ratios for each combination of age, sex and village. Statistical analyses were carried out using STATA 9.0.
Modelling of intervention strategies
We modelled the potential impact of various intervention strategies that targeted high global risk individuals and those with known CVD with medical treatments among the 34 533 adults (≥30 years) living in the 20 study villages.
First, we estimated the number of CHD events that would occur in this population in 10 years, if there was no intervention. The pre-treatment blood pressure levels of individuals who were already on blood pressure-lowering medication were estimated by adding 10 mm Hg to the systolic blood pressure and 5 mm Hg to the diastolic pressure.20 We did not alter the cholesterol level of the pre-treatment population because only a small percentage (0.5%) reported the use of cholesterol-lowering medication and no individuals were on cholesterol-lowering medication alone. We then estimated the number of expected CHD events that would be prevented in 10 years assuming ‘status quo’, ie, if individuals reporting treatment in the survey continued their current treatment for 10 years.
Second, assuming the effectiveness of blood pressure-lowering and cholesterol-lowering therapies as per meta-analyses of these types of drugs,21 22 we estimated the number of events that could be prevented with the introduction of various strategies that targeted treatment to all individuals who have established CVD and additionally targeted treatment to all individuals at high global CHD risk.
For each target group we investigated the potential impact of three drug treatment scenarios: blood pressure-lowering treatment; blood pressure and cholesterol-lowering treatment and treatment with a combination pill (one pill containing three blood pressure-lowering drugs, a statin and aspirin). There is less evidence justifying the effectiveness and safety of antiplatelet therapy in primary prevention;23 24 however, it is a constituent of current combination pill formulations. We assumed a RR of 0.8 associated with any blood pressure-lowering monotherapy (ie, reduction in the number of events by 20%)22 and a RR of 0.8 with any cholesterol-lowering medication (the majority of which were statins).21 We assumed that the effects of the two treatments were multiplicative, producing a RR for both therapies of 0.64 (reduction in the number of events by 36%).25 We also estimated the effects of a combination pill using an optimistic RR of 0.38.26
In addition, for each scenario we calculated the cost of medications required for each strategy using prices obtained in November 2010 from CIMS and Cadila, producer of the Polycap trade mark, for hydrochlorothiazide 25 mg (Indian rupees (INR) 1.1=US$0.025 per tablet), simvastatin 40 mg (INR 7.5=US$0.17 per tablet) and the combination pill, Polycap (INR 14=US$0.32 per tablet). Finally, to provide a comparison with a single risk factor strategy, we modelled the anticipated events avoided and the costs of intervention strategies for single risk factor treatment (either an elevated blood pressure and/or total cholesterol) and not on the basis of the absolute CHD risk.
Results
Risk distribution, risk factor screening and awareness of risk
Based on data from 1079 participants who provided questionnaire, measurement and blood assay data 3.5% (95% CI 2.1% to 4.9%) of adults aged 30 years or older in the 20 villages had established CVD, 7.6% (95% CI 6.2% to 8.9%) had a high global CHD risk, 15.6% (95% CI 13.4% to 17.8%) had a moderate global CHD risk and 76.8% (95% CI 74.6% to 79.1%) had a low global CHD risk. Risk factor levels are described in table 1.
Risk factor profile of all participants, broken down according to their risk factor category
Sixty-seven per cent (95% CI 63.6% to 70.3%) had previously received blood pressure screening and this was higher in women compared with men, p<0.001. Thirty-seven per cent (95% CI 33.7% to 40.3%) reported receiving diabetes screening and only 5.9% (95% CI 4.2% to 7.5%) cholesterol screening, with similar results for men and women.
Of the participants, 56.7% (95% CI 53.1% to 60.2%) understood the risk of heart disease would be reduced by smoking cessation, 47.6% (95% CI 44.1% to 51.2%) by physical activity, 59.6% (95% CI 56.1% to 63.1%) by reducing dietary fat and 59.2% (95% CI 55.7% to 62.8%) by reducing salt consumption. In every response, men were better informed than women.
Preventive treatments
Individuals with CVD
In patients with established disease 49.3% (95% CI 28.8% to 69.8%), 19 people, reported taking blood pressure-lowering medication, 24.1% (95% CI 7.7% to 40.6%), 11 people, were taking antiplatelet therapy and 4.6% (95% CI 0% to 10.4%), three people, were taking cholesterol-lowering therapy. (Note, we have reported secondary prevention treatment levels in this population previously.9 The levels here are slightly different as the definition of CVD in this paper does not include angina and these calculations are based on the 1079 with complete data including lipids).
With respect to behaviour modification, 26.9% (95% CI 2.6% to 51.1%) of smokers, five people, tried to quit, 16.7% (95% CI 0.9% to 32.4%) of overweight individuals, two people, tried to lose weight, 24.6% (95% CI 9% to 40.3%), 10 people, had increased their physical activity, 76.4% (95% CI 56.3% to 96.5%), 31 people, had decreased dietary salt or fat and 68.5% (95% CI 48.9% to 88.1%), 24 people, had increased their fruit or vegetable intake.
Individuals without CVD
In patients at high global CHD risk 29.5% (95% CI 19.5% to 39.5%), 29 people, reported taking blood pressure-lowering medication, 9.6% (95% CI 2.7% to 16.6%), nine people, were taking antiplatelet treatment and 2.8% (95% CI 0% to 6.7%), two people, were taking cholesterol-lowering medication. Treatment levels were lower for lower risk individuals (figure 1). The average CHD risk of individuals who were receiving any form of treatment was 14.6% (95% CI 12.4% to 16.8%), compared with 6.4% (95% CI 5.9% to 6.8%) in the untreated population and 7.4% (95% CI 5.9% to 6.8%) overall.
Percentage of individuals aged 30 years and older from 20 villages in rural Andhra Pradesh, India, who reported taking blood pressure (BP)- lowering, cholesterol-lowering or antiplatelet medications or who reported losing weight, increasing exercise, modifying their diet or quitting smoking in the past 12 months. Individuals are stratified by absolute CHD risk using a recalibration of the Framingham risk equation. High risk are those with a 10-year CHD risk of over 20%, moderate risk are those with a 10-year CHD risk of 10-20% and low risk are those with a 10-year CHD risk of less than 10%.
With respect to behaviour modification: Among high global CHD risk individuals 24.8% (95% CI 15.8% to 33.8%) of smokers, 35 people, reported attempting to quit in the past 12 months, 28.3% (95% CI 7.6% to 49%) of overweight individuals, six people, reported trying to lose weight, 19.4% (95% CI 10.9% to 28%), 20 people, increased physical activity, 60.1% (95% CI 49.3% to 71%), 63 people, reduced dietary fat or salt and 52.9% (95% CI 41.9% to 63.8%), 48 people, increased fruit or vegetable intake. This was similar to lower risk individuals (p values for trend across high, moderate, low risk groups all >0.087; figure 1).
Estimated effects of improved prevention strategies
No treatment
In the total population of 34 533 individuals aged 30 years or more in the 20 study villages an estimated 1203 people had established CVD and were assigned an absolute CHD risk of 40%.27 Based on pre-treatment risk factor levels, an estimated 2655 (8%, 95% CI 6.6% to 9.4%) people were at high CHD risk, 5366 (16.1%, 95% CI 13.8% to 18.4%) at moderate risk and 25 309 (75.9%, 95% CI 73.7% to 78.2%) people were at low global CHD risk. The mean 10-year global CHD risks of the high, moderate and low-risk groups were 32.6% (95% CI 30% to 35.2%), 14% (95% CI 13.6% to 14.5%) and 3.5% (95% CI 3.3% to 3.7%), respectively. We estimate 2984 fatal or non-fatal CHD events to occur in 10 years if this population was left untreated.
Status quo treatment
We calculated the number of events that would be expected to be avoided in 10 years if the levels of treatment of blood pressure and cholesterol reported in this survey continued. The survey indicates an estimated 593 of the 1203 with established CVD are taking blood pressure-lowering medication and 56 of these people are taking both blood pressure-lowering and cholesterol-lowering medications. In addition, 4158 people without established CVD reported taking blood pressure-lowering medication and 213 of these people were also taking cholesterol-lowering medication. No one in the population was taking cholesterol-lowering medication alone. Therefore, in the entire population 4752 (14%) were on blood pressure-lowering medication with or without cholesterol-lowering medication. If current treatment levels were to continue we estimate 5.5% of CHD events over 10 years would be avoided: 2984 events would be reduced to 2821 events, thereby avoiding 163 events.
Intervention strategies
If all patients with established CVD and all those at high risk of CHD were treated with blood pressure-lowering treatment, we would expect 9% of anticipated events to be avoided at an estimated total medication cost of US$349 461 over 10 years or US$1299 per event avoided. If, in addition, such patients received cholesterol-lowering treatment, we would expect 16% of events to be avoided at a cost of US$5633 per event avoided. If all were treated with a combination pill, we would expect 28% of events to be avoided at a cost of US$5327 per event avoided (table 2).
Comparison of modelled absolute risk-based strategies if implemented in an untreated population
Comparison with single risk factor strategies
If all patients with hypertension were to receive blood pressure-lowering treatment, a larger number of individuals in the population would receive treatment compared with a high-risk strategy (27% vs 11%) but a similar number of events would be avoided. Therefore, the cost per event avoided would be higher: US$2990/event avoided versus US$1299/event avoided. Targeting individuals with high blood pressure or cholesterol would be less efficient (table 3).
Comparison of modelled single risk factor-based strategies if implemented in an untreated population
Discussion
This study finds serious deficiencies in the prevention of CVD in this rural region of India. The use of confirmed preventive drug treatments and behaviour modification in those with existing CVD and those at high global CHD risk was very low in this population. We demonstrate here that strategies that target the relatively small number of individuals at very high cardiovascular risk with evidence-based treatments could prevent as many as 28% of cardiovascular events over 10 years. Such risk-based strategies are likely to be affordable in India because of low-cost generic drugs. The annual cost of the treatments for a programme for this region, based on current costs of medications in India, is US$444 800 or US$13 per person. This is far more efficient than single risk factor strategies or the status quo for this region. A targeted intervention strategy in an area such as Andhra Pradesh, where the prevalence of CVD is still relatively low, has the potential for enormous cost savings because it would treat a relatively small number of people and lead to a substantial reduction in cardiovascular events in the short to medium term.
The benefits of blood pressure-lowering, cholesterol-lowering and antiplatelet medications have been clearly demonstrated,21–23 and their prescription to those at high CHD risk for the prevention of events is universally recommended by treatment guidelines.28 29 The treatment gaps in high CHD risk people found in this study, less than one third on blood pressure-lowering therapy and less than 10% on cholesterol-lowering medications, are substantially greater than the gaps documented in high-income countries. For example, two-thirds of Australian individuals at high CHD risk are prescribed blood pressure-lowering therapy and more than one-third are taking cholesterol-lowering medications.30 This could be because high-risk individuals are not identified as well by health services in India, although in this population a large proportion had received some CHD risk screening (∼70% had received a blood pressure check). The high rates of risk factor screening can be attributed to a recent blood pressure and diabetes screening programme run in this region by the Byrraju Foundation, a not-for-profit organisation.
Modification of behavioural risk factors such as smoking cessation, improving diet quality and increasing physical activity was also poor in this population. This could be because of low awareness of these factors being important determinants of CVD. Only approximately half of the participants knew there was an association between smoking or decreased physical exercise and heart disease. Our findings are consistent with those reported in other low and middle-income countries, for example, in tertiary care hospitals in Pakistan one-third of people recognised smoking as a risk factor for CVD and one-fifth recognised exercise.31
The information on costs provided in this analysis is limited to a rough comparison of medication costs only. While the costs of blood pressure medications are already low, it is possible that the costs of cholesterol medications and combination pills may be reduced in the future. It is also of note that costs associated with prescribing a combination pill may be less than prescribing all the components separately, and this may make a combination pill strategy more efficient. However, while this comparison of costs is simplistic it does highlight the cost benefit of a risk-targeted approach in comparison with single risk factor strategies and gives some indication of the costs of preventing CVD in rural India.
With respect to the broader applicability of our findings, this study was performed in a single region of rural India. This region is more affluent and better developed than many other rural areas of India, with the support of a local not-for-profit organisation conducting hypertension and diabetes programmes in this region. It is therefore possible that treatment gaps could be even greater in less privileged rural areas. Regarding other limitations, much of this study relied on self-reported information. Ideally, we would have validated self-reported information against medical records, but there is epidemiological evidence for the validity of using self-reporting to obtain information on cardiovascular risk factors and disease status,32 33 and this has specifically been addressed in this population.9 The estimates of events prevented were based on modelling of survey results and cannot be corroborated by data from cohort studies as none exist in India at this time. The strengths of this study include that it is a large observational study, utilising a carefully designed and representative population sampling method with high response rate and comprehensive measures of cardiovascular risk factors.
The main implication of our findings is that while cardiovascular prevention is seriously suboptimal in this rural region of India, prevention strategies that put those at high global risk on simple confirmed treatments have potential to curtail an epidemic of cardiovascular events substantially. Such strategies are likely to be efficient and highly cost effective in India.
Acknowledgments
The authors would like to thank all the collaborators of the Andhra Pradesh Rural Health Initiative, which is a is a collaboration between four partners, the Byrraju Foundation in Hyderabad, India, the Center for Chronic Disease Control in Delhi, India, the Care Foundation in Hyderabad, India and the George Institute for Global Health in Sydney, Australia. They would also like to thank the communities of the participating villages in east and west Godavari districts for their tremendous support of the project.
References
Footnotes
Funding This work was supported by the Byrraju Foundation and the George Institute for Global Health. The authors did not receive any specific financial support with respect to the writing or development of this manuscript. CKC is supported by a fellowship cofounded by the National Heart and Medical Research Council of Australia, the National Heart Foundation of Australia and the Sydney University Chapman fellowship. BN and AP were supported by fellowships from the National Heart Foundation of Australia while doing this work. This work was also supported by a NHMRC grant (358395).
Competing interests All authors have completed the unified competing interest form at http://www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that AW, JP, AP, BN, KJ and CKC have support from the George Institute for the submitted work; AW, JP, AP, BN, KJ and CKC have no relationships with companies that might have an interest in the submitted work in the previous 3 years; their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and AW, JP, AP, BN, PKR and CKC have no non-financial interests that may be relevant to the submitted work.
Patient consent Obtained.
Ethics approval This study was conducted with the approval of the ethics committees of the CARE Hospital (Hyderabad, India) and the University of Sydney, Australia.
Provenance and peer review Not commissioned; externally peer reviewed.