4. Vascular Risk

Key Questions

What systems are available to assess vascular risk?

In what population and how often should vascular risk be assessed?

4.1. Importance of vascular risk

The etiology of stroke, myocardial infarction and peripheral arterial disease are multifactorial and the different SRs, mainly in secondary prevention, have demonstrated how several treatments not only prevent stroke but also other vascular episodes. Hence, the decision to initiate an intervention or preventive treatment should be guided by the estimation of the risk of developing one of these vascular episodes. Thus, preventive interventions do not only reduce the risk of having a stroke, but also the risk of myocardial infarction and peripheral arterial disease¹⁸.

4.2. Vascular risk factors

Coronary disease and stroke share several risk factors, but the importance of each one of them in these conditions is not the same. In contrast to coronary disease, the most important risk factor of stroke is hypertension (HT) (relative risk [RR]>4), this factor being the only one consistently associated with all types of strokes. Other factors, as occurs in coronary disease, present more moderate associations (RR=2 to 4)¹⁹.

SR of RCT
1+

Although numerous markers (biochemical, ankle-arm index, carotid intima-media thickness via ultrasound, coronary calcium index via computerised tomography) have recently been described, their use is yet unclear and their application would be aimed, in theory, at a more detailed assessment of people with moderate vascular risk ^{20, 21}.

Observational studies
2+

4.3. Vascular risk calculation tables

Due to the multifactorial etiology of vascular disease, when the effect of a certain risk factor is estimated in an individual, other factors should be taken into account. An individual’s vascular risk is calculated using equations of vascular risk, which establish excess risk in relation to the population’s average.

The most widely used tables to calculate vascular risk in our setting are: the Framingham table, the REGICOR (Registre Gironí del Cor) table and the SCORE (Systematic Coronary Risk Evaluation)^22-24 table, which differentiate sex and age assessments as non-modifiable risk factors and, additionally, incorporate blood pressure and cholesterol values, being a smoker or not, and, sometimes, the presence of diabetes.

Cohort studies
2+

Table 1 shows, for example, REGICOR’s different estimations of coronary risk at 10 years in a 50-year old person taking into account the presence or absence of one or several risk factors and specific cholesterol, cholesterol HDL (high density lipoprotein) and blood pressure values.

Table 1. Impact of exposure to one or multiple risk factors on absolute coronary risk in a 50-year old man ³⁵

Cholesterol total (mg/dl)	Cholesterol HDL (mg/dl)	Diabetes	Blood pressure (mmHg)	Smoking	Coronary risk at 10 years
275	62	No	115/76	No	3%
210	50	No	170/94	No	5%
210	50	No	138/88	Sí	5%
230	34	No	152/94	Sí	10%
250	32	Sí	144/90	Sí	19%

*Risk calculated using the REGICOR table, valid for the Spanish population.

Adapted from: Department of Health of the Generalitat de Catalonia. Llibre blanc. Consens sobre les activitats preventives a l’edat adulta dins l’atenció primària. Barcelona: Directorate General for Public Health, 2005.

Framingham’s tables have been used very frequently. Recently a new equation has been developed that includes the risk of stroke, although it overestimates risk in low-risk populations, and underestimates risk in higher risk populations ^{25 , 26}.

Cohort studies
2+

The REGICOR tables are the calibration of Framingham’s equation in our setting. These tables estimate the risk of coronary morbimortality in individuals aged between 35 and 74 years, differentiate diabetic patients from those who are not and include the assessment of HDL cholesterol²⁷. The SCORE tables include populations from different European regions and estimate the probability of vascular death in the population aged up to 65 years. These tables recommend a corrective factor for the calculation of risk in the diabetic population and include stroke in the estimation of vascular risk²⁴.

Table 2 shows the main differentiating characteristics of the REGICOR and SCORE tables. Annex 2 presents the SCORE tables for the low risk areas of Europe and REGICOR.

Table 2. Comparison of the main differences between the REGICOR and SCORE tables³⁵

	REGICOR	SCORE
Type of measure	Morbimortality	Mortality
Events included	Fatal or non-fatal or silent myocardial infarction, angina	Coronary death, cerebral vascular disease, peripheral arteriopathy, cardiac insufficiency, amongst others
Definition of high risk	>10%	>5%
Methodology	• Calibration of the equation based on a cohort study • Validated in our setting	• Equation based on a cohort study • Calibrated in our setting
Specific assessment of diabetic patients	Yes	No*

*The SCORE equation considers them to be high risk.

Adapted from: Department of Health of the Generalitat of Catalonia. Llibre blanc. Consens sobre les activitats preventives a l’edat adulta dins l’atenció primària. Barcelona: Directorate General of Public Health, 2005.

Different studies on the calibration, validation and comparative analysis of different tables demonstrate that all of them still provide inaccurate estimations^29-31. Hence, these tables are at present a complementary diagnostic tool that should be considered jointly with the individual characteristics of each specific patient¹⁸. The subsequent decision to implement a preventive strategy and, even more importantly, if it is pharmacological, should consider the risk-benefit balance of this strategy and the patient’s values and preferences.

Cohort studies
2+

The differences highlighted amongst the different tables of vascular risk estimation demonstrate that they do not identify the same profile of high-risk patients. Therefore, the same patient may or may not be a candidate for treatment depending on the risk calculation table used³². The economic impact of recommending the generalised use of one of the existing tables is a very relevant question but one that exceeds the scope of this guideline.

4.4. Vascular risk reduction strategies

The decision to initiate preventive strategies in the high-risk general population is still linked to a widespread debate regarding its real effectiveness and efficiency in relation to the cost and allocation of resources. Usually, high vascular risk is deemed to be an estimation higher than 5% of having a fatal vascular episode at 10 years according to SCORE tables or an estimation higher than 20% of having a coronary episode (fatal or not) at 10 years in the case of the REGICOR tables ^{24 , 27}.

All these tables are for specific use in patients without known vascular disease. People with evidence of previous vascular disease present, regardless of the result obtained in the table, high vascular risk and should undergo more intensive preventive and therapeutic strategies ¹⁸. Figure 2 shows an intervention algorithm proposal based on the estimation of vascular risk.

Figure 2. Intervention algorithm based on the estimation of vascular risk¹⁴

Figura 2

Adapted from: Diez Tejedor E, Fuentes B, Gil Núñez AC, Gil Peralta A, Matías Guiu J, by the ad hoc committee of the SEN’s (Spanish Society of Neurology) Study Group for Cerebrovascular Diseases. “Guía para el tratamiento preventivo de la isquemia cerebral”. At: Guía para el tratamiento y prevención del ictus. Guidelines and procotocols of the SEN. In Díez Tejedor (ed.). Ed. ISBN: 84-8124-225-X. Barcelona: Prous Science, 2006: 133-183.

Despite the previous information, there are no clinical trials that assess the efficacy of different preventive strategies on populations with different vascular risk. Additionally, a systematic review (SR) showed that the use of vascular risk tables does not reduce overall vascular risk²⁵. However, in recent monitoring of patients with elevated plasma cholesterol levels that required hypolipemiant treatment, those who were informed on their level of vascular risk showed a more significant decrease of cholesterol values, and, essentially, of the risk profile³³.

RCT
SR of RCT
1+

It is important to calculate overall vascular risk in patients who so require it, a calculation that is not habitually performed at the present time. Specifically, a European study conducted in primary care reported that only 13% of the physicians consulted performed this calculation systematically on their patients, while 43% only does it occasionally.³⁴

Summary of the Evidence

2+	There are different systems to assess vascular risk in the general population, although all of but all of them present certain limitations ^22-32.
2+	Framingham’s table overestimates vascular risk in our setting .^25,26
2+	The SCORE table evaluates vascular mortality and includes the risk of death due to stroke.²⁴
2+	The REGICOR table assesses the risk of coronary morbimortality validated in our setting.²³

Recommendations

B	The calculation of vascular risk using one of the available risk tables (REGICOR or SCORE) is recommended as a complementary diagnostic tool in the clinical assessment of patients.
B	The SCORE table is recommended to calculate the risk of stroke.
√	Vascular risk should be assessed at least once every five years after the age of 40.
√	In patients with high vascular risk, it should be assessed at least once every year.
√	It is important that health care professionals be adequately trained for vascular risk calculation, and that such vascular risk calculation be integrated into the IT systems available at the medical consultation office.

Section 04 Bibliography

Access to the full bibliography

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