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What is a high-risk patient? 

What is a high-risk patient?
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What is a high-risk patient?
DOI:
10.1093/med/9780199674039.003.0002
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date: 25 February 2021

The association between total CVD risk and the benefits of prevention

  • The magnitude of cardiovascular benefits from preventive interventions is determined mainly by a person’s total CVD risk, rather than by the level of an individual risk factor or how much a risk factor is lowered. This is demonstrated in Fig. 2.1, a meta-analysis of trials of low-density lipoprotein cholesterol (LDL-C) lowering.

  • A similar meta-analysis has shown that the benefits of lowering BP are also determined primarily by a person’s total CVD risk rather than by the BP level or by how much BP is lowered.

Figure 2.1 Vascular deaths avoided through lowering LDL-C with statins by different amounts in people at different levels of pre-intervention total CVD risk (based on a meta-analysis of randomized controlled trials (RCTs) of statins).

Figure 2.1 Vascular deaths avoided through lowering LDL-C with statins by different amounts in people at different levels of pre-intervention total CVD risk (based on a meta-analysis of randomized controlled trials (RCTs) of statins).

Reprinted from Lancet, 280/9841, Cholesterol Treatment Trialists’ (CTT) Collaborators, The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials, 581–90, Copyright (2012) with permission from Elsevier.

Estimating total CVD risk

  • Total CVD risk (i.e. the probability of having a CVD event during a defined time period) is determined by the combined effect of all CVD risk factors present.

  • People with identical BP levels (or another single risk factor) may have more than tenfold differences in their total CVD risk, depending on the presence or absence of other CVD risk factors, as illustrated in Fig. 2.2.

  • CVD risk factors interact, sometime multiplicatively, so it is not possible to estimate a person’s total CVD risk simply by summing risk factors.

  • Total CVD risk is typically estimated using a two-step process. First, people with evidence of pre-existing CVD or end-organ damage are classified at very high risk. For the remainder, total CVD risk is usually estimated using a chart or computer program derived from mathematical risk algorithms that are based on studies that have followed people after measuring their CVD risk factor profiles.

  • A wide range of risk charts and computer algorithms are available for estimating total CVD risk (e.g. Systematic COronary Risk Estimation (SCORE)).

Figure 2.2 Total CVD risk (%) over 5 years by systolic BP (SBP) level (each set of vertical bars represents the same range of SBP levels from 110 to 180 mmHg) depending on the accumulation of other CVD risk factors. Reference category are 50-year-old, non-smoking, non-diabetic women with total cholesterol (TC) = 4.0 mmol/L and HDL = 1.6 mmol/L.

Figure 2.2 Total CVD risk (%) over 5 years by systolic BP (SBP) level (each set of vertical bars represents the same range of SBP levels from 110 to 180 mmHg) depending on the accumulation of other CVD risk factors. Reference category are 50-year-old, non-smoking, non-diabetic women with total cholesterol (TC) = 4.0 mmol/L and HDL = 1.6 mmol/L.

Reprinted from Lancet, 365, Jackson R, Lawes C, Bennett D, Milne R, Rodgers A., Treatment with drugs to lower blood pressure and blood cholesterol based on an individual’s absolute cardiovascular risk, 434–41, Copyright (2005) with permission from Elsevier.

Categories of total CVD risk

  • The European Joint Societies Task Force on Cardiovascular Disease Prevention in Clinical Practice state that ‘the higher the risk the greater the benefits from preventive efforts’.

  • The Task Force uses four priority groups (see Table 2.1) to classify people according to their estimated risk. Those at highest risk gain most from risk factor management.

  • Each of the common risk reduction interventions (smoking cessation, lipid lowering, BP lowering, antiplatelet therapies) is estimated to reduce the total CVD risk by 15–30% over about 5 years, while a combination of at least three of these interventions is likely to reduce risk by over 50%.

  • Therefore after categorizing a person according to their total CVD risk, it is possible to estimate the approximate number of people with a similar risk who would need to be treated to prevent one CVD event over a defined time period.

Key reading

Blood Pressure Lowering Treatment Trials (BPLTT) Collaboration. Blood pressure-lowering treatment based on cardiovascular risk: a meta-analysis of individual patient data. Lancet 2014; 384:591–98.Find this resource:

Cholesterol Treatment Trialists’ (CTT) Collaborators. The effects of lowering LDL cholesterol with statin therapy in people at low risk of vascular disease: meta-analysis of individual data from 27 randomised trials. Lancet 2012; 380:581–90.Find this resource:

European Society for Cardiology, European Association for Cardiovascular Prevention & Rehabilitation. HeartScore. [Online] http://www.heartscore.org/Pages/welcome.aspx

Jackson R, Lawes C, Bennett D, et al. Treatment with drugs to lower blood pressure and blood cholesterol based on an individual’s absolute cardiovascular risk. Lancet 2005; 365:434–41.Find this resource:

Perk J, De Backer G, Gohlke H, et al. European Guidelines on cardiovascular disease prevention in clinical practice (version 2012). The Fifth Joint Task Force of the European Society of Cardiology and Other Societies on Cardiovascular Disease Prevention in Clinical Practice (constituted by representatives of nine societies and by invited experts). Eur Heart J 2012; 33:1635–701.Find this resource:

Wald NJ, Law MR. A strategy to reduce cardiovascular disease by more than 80%. BMJ 2003; 326:1419.Find this resource: