Assessment of total cardiovascular risk using WHO/ISH risk prediction charts in three low and middle income countries in Asia.

Dugee Otgontuya,Ruth Bonita,Brian S Buckley,Sophal Oum

doi:10.1186/1471-2458-13-539

Abstract

BackgroundRecent research has used cardiovascular risk scores intended to estimate “total cardiovascular disease (CVD) risk” in individuals to assess the distribution of risk within populations. The research suggested that the adoption of the total risk approach, in comparison to treatment decisions being based on the level of a single risk factor, could lead to reductions in expenditure on preventive cardiovascular drug treatment in low- and middle-income countries. So that the patient benefit associated with savings is highlighted.MethodsThis study used data from national STEPS surveys (STEPwise Approach to Surveillance) conducted between 2005 and 2010 in Cambodia, Malaysia and Mongolia of men and women aged 40–64 years. The study compared the differences and implications of various approaches to risk estimation at a population level using the World Health Organization/International Society of Hypertension (WHO/ISH) risk score charts. To aid interpretation and adjustment of scores and inform treatment in individuals, the charts are accompanied by practice notes about risk factors not included in the risk score calculations. Total risk was calculated amongst the populations using the charts alone and also adjusted according to these notes. Prevalence of traditional single risk factors was also calculated.ResultsThe prevalence of WHO/ISH “high CVD risk” (≥20% chance of developing a cardiovascular event over 10 years) of 6%, 2.3% and 1.3% in Mongolia, Malaysia and Cambodia, respectively, is in line with recent research when charts alone are used. However, these proportions rise to 33.3%, 20.8% and 10.4%, respectively when individuals with blood pressure > = 160/100 mm/Hg and/or hypertension medication are attributed to “high risk”. Of those at “moderate risk” (10- < 20% chance of developing a cardio vascular event over 10 years), 100%, 94.3% and 30.1%, respectively are affected by at least one risk-increasing factor. Of all individuals, 44.6%, 29.0% and 15.0% are affected by hypertension as a single risk factor (systolic ≥ 140 mmHg or diastolic ≥ 90 mmHg or medication).ConclusionsUsed on a population level, cardiovascular risk scores may offer useful insights that can assist health service delivery planning. An approach based on overall risk without adjustment of specific risk factors however, may underestimate treatment needs.At the individual level, the total risk approach offers important clinical benefits. However, countries need to develop appropriate clinical guidelines and operational guidance for detection and management of CVD risk using total CVD-risk approach at different levels of health system. Operational research is needed to assess implementation issues.

Highlights

Recent research has used cardiovascular risk scores intended to estimate “total cardiovascular disease (CVD) risk” in individuals to assess the distribution of risk within populations
Total CVD risk is determined according to charts or equations that take into account the co-existence in an individual of a range of risk factors such as age, sex, tobacco use, body mass index, diabetes, raised blood pressure and a variety of biochemical indicators
Using nationally representative population data, this study provides first-ever estimates of population-distribution of CVD risk in three low- and middle-income countries (LMIC) (Cambodia, Mongolia, and Malaysia) countries at different stages of socio-economic, demographic and epidemiological transition

Summary

Introduction

Recent research has used cardiovascular risk scores intended to estimate “total cardiovascular disease (CVD) risk” in individuals to assess the distribution of risk within populations. The research suggested that the adoption of the total risk approach, in comparison to treatment decisions being based on the level of a single risk factor, could lead to reductions in expenditure on preventive cardiovascular drug treatment in low- and middleincome countries. A reduction of CVD morbidity and premature mortality has been achieved through a combination of three strategies: population-level risk factor reduction strategies; individual-based primary prevention strategies targeted at high-risk groups to prevent the onset of CVD through risk factor reduction; and secondary prevention and treatment to prevent disease progression in people with established CVD [3]. Research from several countries has consistently shown that treatments of established CVD explain less of the decline than reductions in risk factors to prevent development of cardiovascular disease. Recent research suggests that compared with the vertical treatment approach, adopting pharmaceutical treatment strategies based on the total CVD risk assessment approach offers considerable savings [10,11]. The 2007 WHO guidelines for primary prevention of CVD recommend the second approach by targeting limited healthcare resources most cost-effectively at high-risk groups to prevent CVD [12]

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