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Moving from risk factor assessment to atherosclerosis imaging to select the most appropriate patient for primary prevention: CVD algorithms underestimate risk in HIV+
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Reported by Jules Levin
EACS Nov 11-14 2009 Cologne Germany
Giovanni Guaraldi1, Stefano Zona1, Alberto Roverato2, Gabriella Orlando1, Federica Carli1, Guido Ligabue3, Rosario Rossi4, Maria
Grazia Modena4, and Paolo Raggi5
Picture of the famous old cathedral on the river in Cologne
AUTHOR DISCUSSION & CONCLUSION
As expected, Framingham risk prediction algorithm is not a reliable clinical tool for identification of patient who qualify for primary prevention. Agreement between Framingham and clinical tools is less than ideal.
NCEP and ESH showed a similar proportion of patients who qualify for primary prevention. Both of them underestimate the proportion of patients identified with Framingham combined with CAC score.
From 22% to 41 % of HIV infected patients were eligible for treatment according to applied clinical tools. Proper identification of these patients may be clinically relevant in the prevention of CVD.
This study suggests that HIV asymptomatic young individuals may be reasonable candidates for electron bean CT as a potential means of modifying risk prediction and altering therapy.
From Jules: Figure 2 below depicts that 8.3% of HIV+ individuals do not need primary prevention intervention for heart disease when using the Framingham Risk Score despite having a high risk score when evaluated by CT (computed tomography) for coronary artery calcium (CAC).
ABSTRACT
Objective
All HIV-infected adults should undergo coronary heart disease risk assessment with Framingham Risk Score (FRS) to guide preventive treatment intensity. European Hypertension Guidelines (ESH-ESC), National Cholesterol Education Program (NCEP) III and the Multi- Ethnic Study of Atherosclerosis developed algorithms to identify people who qualify for primary prevention, to avoid FRS intermediate risk category (10-20% cardiovascular disease probability) in
whom clinical decision making is most uncertain. These algorithms combine blood pressure measurement with cardiovascular risk factors (RF), FRS with RF and FRS with coronary artery calcium (CAC) respectively. The purpose of this study was to identify people who qualify and not qualify for primary prevention for CVD according to ESH-ESC, NCEP-FRS and CAC-FRS across coronary calcium score strata in all HIV infected patients and in the subset of female and young (<55 yrs if males and <65 if females) patients.
Methods
Observational cross-sectional study HIV-infected patients receiving ART.
All patients underwent estimation of cardiovascular RF, FRS and CAC assessed with computed tomography. Cohen's K statistics was used to measure the inter-rater agreement between ESH-ESC, NCEP-FRS and CAC-FRS.
Results
724 patients were analyzed, 522 (72%) were males, mean age was
47 (± 7) years.
FRS was low in 508 (71%) patients, intermediate in 150 (22%) and
high in 53 (7%) patients. CAC was null in 467 (66%), 1-99 in 177 (24%) and >100 in 71 (10%) of the patients.
Figure 1 compares the rate of patients who qualify for primary prevention according to ESH-ESC, NCEP-FRS and CAC-FRS.
Table 1 depicts agreement between algorithms.
Figure 2 compares in the whole population and in female and young subset the proportion of people not qualifying for treatment despite a CAC>100.
Conclusion
ESH-ESC, NCEP-FRS seem to underestimate cardiovascular risk in young and women, whom assessment of CAC may provide incremental value to global risk assessment.
BACKGROUND
All HIV-infected adults should undergo coronary heart disease (CVD) risk assessment with Framingham Risk Score (FRS) to guide preventive treatment intensity.
Framingham algorithm has been shown to predict CVD in the D:A:D cohort nevertheless it has not been validated in HIV infected patients.
Framingham algorithm underestimate CVD risk in young individuals (< 50 in males, < 60 if females) both HIV infected and general population. Moreover Framingham intermediate risk category (10%-20% risk prediction in 10 yrs) do
not provide meaningful clinical suggestion.
A renewed attitude for prevention of cardiovascular disease suggests a changing paradigm in clinical assessment, moving from risk prediction to identification of people who qualify for CVD primary prevention.
The following tools have been developed to help physicians in identification who qualify for primary prevention:
1. National Cholesterol Educational Programs (NCEP): treatment is offered according to LDL goals identified from the combination of the number of risk factors and Framingham categories;
2. European Society of Hypertention (ESH): treatment is offered according to cross match between BP value and and Framingham categories;
3. Coronary Plaque as a replacement for age as a risk factor in Framingham algoritm (CAC- FRS): treatment is offered for CAC-FRS>20%; Coronary artery calcium (CAC) is a vascular marker of sub-clinical atherosclerosis that has
been used as a surrogate marker of CVD by virtue of its strong association with subsequent cardiovascular events. Absolute CAC amount >100 is recognized as a reliable surrogate marker of cardiovascular events as shown by correlation with pathological specimen.
OBJECTIVE
The purpose of this study was to identify people who qualify and not qualify for primary prevention for CVD according to ESH, NCEP and CAC-FRS across coronary calcium score strata in all HIV infected patients and in the subset
of young (<55 yrs if males and <65 if females) patients.
METHODS
Observational cross-sectional study HIV-infected patients receiving ART.
All patients underwent estimation of cardiovascular RF, FRS and CAC screening with multidetector computed tomography imaging with a Volume CT 64-slice scanner (GE Medical Systems).
Cohen's K statistics was used to measure the inter-rater agreement between ESH-ESC, NCEP-FRS and CAC-FRS.
Differences of proportions were analyzed using the two-sample proportion test.
RESULTS
724 patients underwent multislice CT to assess coronary artery calcium (CAC). 5 patients were not evaluated with Framingham and were excluded. 519 (72%) were males, mean age was 47 (± 8) years. FRS was low in 508 (71%) patients, intermediate in 150 (22%) and high in 53 (7%) patients.
CAC was null in 467 (66%), 1-99 in 177 (24%) and >100 in 71 (10%) of the patients.
Table 1 shows patients' clinical characteristics.
Figure 1 compares the rate of patients who qualify for primary prevention according to Framingham, ESH, NCEP, and CAC-FRS.
Table 2 shows p-values of differences in proportions between algorithms.
Table 3 depicts inter-rater statistical agreement between clinical algorithms.
Figure 2 compares the proportion of people not qualifying for treatment according to different algorithms despite a CAC≥ 100.
BMI, Body Mass Index; IDU, Intravenous drug user; VL, Viral Load; HAART, Highly active anti-retroviral therapy; PI, protease inhibitor; NRTI, nucleoside reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase inhibitor; ATP-III, adult treatment panel III; HOMA-IR, homeostasis model assessment of insulin resistance.
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