1. Funded by US Department of Homeland Security FEMA #EMW-2006-FP-01744
Framingham Risk Score Is Poorly Associated With Subclinical Carotid Atherosclerosis: Results From Firefighter Heart Disease Prevention Project
Funded by US Department of Homeland Security FEMA #EMW-2006-FP-01744

2. Background
Firefighters are fit and generally believed to follow a vigorous life-style
Cardiovascular disease and cardiovascular mortality has been reported to be highly prevalent in firefighters
In the Toronto Fire Department study the mortality ratio for fire fighters aged years was 1.73 (p<0.005) compared to non-firefighters
CDC has reported that among volunteer firefighters sudden cardiac death and MVA during emergency response are the leading cause of death and among career firefighters, sudden cardiac death and asphyxiation are the leading causes of death
Compared to non-emergency duties, fire suppression and alarm response carried significantly higher risks (OR =6.4 and 5.6 respectively) of CHD death
Bates JT. J Occup Med Feb;29(2):132-5
MMWR Morb Mortal Wkly Rep 2006;55:
Kales SN. Environ Health 2003;2:14
Kales SN N Engl J Med. 2007;356(12):

3. Background

4. Background More than one million firefighters in US
About 100 firefighters die each year on-Duty (1 in 10,000 per year)
, CVD has caused ~45% on-Duty Deaths
% of On-Duty Deaths
caused by CVD
Firefighters %
Police %
Overall* %
Construction %%

5. Background
Etiology of this high CVD risk in firefighters is unclear
Various biologically plausible explanations include smoke and chemical exposure, irregular physical exertion, the handling of heavy equipment, heat stress, shift work, a high prevalence of cardiovascular risk factors, and psychological stressors
One study describing the prevalence of CHD risk factors among 200 firefighters has reported that the prevalence of obesity, elevated blood cholesterol, and elevated BP exceeded the Healthy People 2010 targets and were higher than the general population
We investigated the relationship between noninvasive measures of atherosclerosis to phenotypic and genotypic markers of atheroslcerosis risk in asymptomatic professional firefighters in order to determine which factors were most closely linked to evidence of atherosclerosis and thus, increased risk for cardiovascular events
Byczek L. AAOHN J. 2004;52:66-76

6. Methods
300 active duty firefighters over the age of 40 years were recruited from the Gwinnett County Fire Department which serves a population of approximately 800,000 individuals
Series of questionnaires that address standard demographic, nutrition, exercise, lifestyle, and family history variables. Standard physiologic measurements were obtained including, resting 12-lead EKG, blood pressure, ankle-brachial index (ABI), height/weight, and waist-to-hip measurements
Coronary Artery Calcium Scoring, carotid intima media thickness
Blood samples were obtained following a 16 hour fast for Plasma lipid and lipoprotein cholesterol, Apolipoprotein B, Lp(a), CRP (hs-CRP), homocysteine and other serological markers

7. Methods
Framingham risk scores (FRS) are used to estimate the 10-year coronary heart disease (CHD) risk in individuals
Non-invasive assessment of subclinical atherosclerosis by means of carotid intima media thickness (cIMT) and coronary artery calcium score (CAC) could improve risk stratification in high risk groups like firefighters
We examined the distribution of FRS scores of cIMT, CAC positive and negative individuals
We hypothesize that FRS is a poor indicator of sub-clinical atherosclerosis in professional firefighters

8. Methods
We studied 159 male firefighters (age, 47±5 yrs) without known coronary, peripheral, or cerebral vascular disease. Each participant underwent clinical and serologic risk factor screening, cIMT, and CAC. Abnormal cIMT was defined as >0.9 mm and CAC score > 0 was considered as evidence of early atherosclerosis

9. Distribution of various cardiovascular risk factors in cIMT+ and cIMT – firefighters
p-value
Age
53.21±5.59
45.91±4.58
1.01E-07
hsCRP
3.42±1.45
2.06±3.53
0.155
Total cholesterol
213.57±31.15
202.73±35.22
0.2689
HDL2b
20.21±3.96
21.60±4.69
0.2869
Lp(a)
64.85±56.04
58.13±67.37
0.7183
logLp(a)
3.73±1.09
3.41±1.18
0.346
HDL-C
46.78±12.82
48.54±13.95
0.652
LDL-C
148.00±32.15
132.95±13.55
0.09 TG
140.92±55.90
137.53±89.14
0.889
SBP average
133.47±14.36
123.22±10.40
DBP average
82.71±8.21
77.75±7.90
0.026
Insulin
9.64±5.10
9.46±5.71
0.909
Glucose
89.43±5.10
86.32±9.22
0.245
BMI
29.48±5.86
29.19±3.93
0.807 WH
0.92±0.056
0.91±0.064
0.668

11. Distribution of cIMT+ and cIMT – firefighters based on Framingham risk scores

13. FRS threshold of 20% (corresponding to low-medium risk) has poor sensitivity for identifying people with abnormal CIMT
FRS(>20%)
FRS(0-20%)
CIMT + - 2 30
145
false negative rate of 93%
false positive rate of 0%.
When using a 20% FRS threshold to predict subclinical carotid atherosclerosis, FRS offers 100% specificity with 7% sensitivity. Thus while this FRS threshold avoids misidentifying individuals without atherosclerosis as being high risk, this same threshold fails to identify individuals who do have atherosclerosis.

14. A substantial number of low FRS individuals (defined as those with scores < 10%) and medium FRS individuals (defined as those who have scores between 10% and 20%) have clinically significant carotid intima-media thickness (> 0.9 mm)

15. Distribution of various cardiovascular risk factors in CAC+ and
CAC – firefighters
N=159
CAC +
CAC -
p-value
Age
48.72±5.62
45.89±4.76
2.73E-03
hsCRP
2.29±1.88
2.15±3.77
0.821
Total cholesterol
209.43±40.71
201.94±32.97
0.254
HDL2b
21.19±4.57
21.56±4.67
0.667
Lp(a)
64.21±69.35
55.84±65.39
0.321
Log Lp(a)
3.68±1.11
3.37±1.19
0.158
HDL-C
49.78±16.77
47.95±12.84
0.483
LDL-C
139.89±39.02
132.57±29.22
0.221 TG
132.81±58.44
139.36±93.62
0.688
SBP average
128.64±13.56
122.76±9.96
DBP average
81.21±8.92
77.27±7.53
0.0084
Insulin
10.24±6.02
9.24±5.71
0.348
Glucose
89.62±9.79
85.79±9.28
0.026
BMI
29.90±4.07
29.02±4.12
0.249
WHR
0.92±0.06
0.91±0.066
0.6

17. Distribution of CAC+ and CAC – firefighters based on
Framingham risk scores (FRS)

19. FRS threshold of 20% (corresponding to low-medium risk) has poor sensitivity for abnormal CAC+ - 2 35
122
false negative rate of 95%
false positive rate of 0%.
When using a 20% FRS threshold to predict CAC, FRS offers 100% specificity but only 5% sensitivity
A substantial number of low FRS individuals (defined as those with scores < 10%) and medium FRS individuals (defined as those who have scores between 10% and 20%) have clinically significant coronary calcification
There is no significant correlation between CAC and FRS (B = and p-value 0.675, age adjusted)

20. Conclusions
In this active professional firefighter cohort, FRS underestimated the presence of premature, subclinical carotid and coronary atherosclerosis. In our observations, a large number of firefighters with low to moderate Framingham risk scores who are not currently treated to the maximal goals have already have evidence of early carotid atherosclerosis.

21. Age adjusted logistic Regression P value
In Asymptomatic Firefighters the Burden of Subclinical Atherosclerosis as Measured by both Coronary Artery Calcification and Carotid Intimal Medial Thickening is associated with Metabolic Abnormalities and but Not with Standard Traditional Serological Risk Factors
n=219
CAC+ CIMT+ (n=52)
CAC- CIMT- (n=167)
P value
Age adjusted logistic Regression P value
log Lp(a)
0.116
0.106 TC
0.175
0.567
LDL-C
0.138
0.499 TG
0.128
0.11
HDL-C
0.31
0.67
HDL 2b%
21 + 5
21 + 4
0.78
0.537
Apo B
93.64+/-25.32
98.58+/-24.98
0.23
0.73
BMI
31 + 5
30 + 4
0.135
0.018
WHR
0.03
0.046
SBP
0.003 WC
7.1+/-2.45
5.92+/-1/24
7.41E-006
0.01
Insulin
0.24
0.26
Glucose
99.29+/-26.49
88.41+/-15.44
30.65+/-5.26
29.53+/-4.5
0.13
0.02

22. Metabolic syndrome +(n=59) Metabolic syndrome -(n=236) P value
Metabolic Syndrome in Firefighters is Associated with Increased Thrombotic and Inflammatory Markers
n=295
Metabolic syndrome +(n=59)
Metabolic syndrome -(n=236)
P value
Age adjusted logisticregression P value
CAC (AU)
124±342
39±174
0.007
0.022
cIMT (mm)
0.76±0.28
0.66±0.20
0.001
0.005
Total Chol
197±39
201±40
0.425
0.386
Lp(a) (mg/dl)
48±73
65±77
0.140
0.171
Fibrinogen (mg/dl)
351±67
330±58
0.019
0.028
PAI-1 (U/ml)
29±17
15±10
2.543E-14
7.58E-09
hs CRP (mg/l)
4.5±7.2
2.3±4.9
0.031
WBC (x10^9/l)
7.0±1.7
6.0±1.7
0.0002
Ferritin (mg/l)
157±128
123±94
0.026
0.042
Distribution of Various risk factors in Firefighters with and with out Metabolic Syndrome

23. Our investigation found that 35
Our investigation found that 35.6% of active duty professional firefighters have evidence of subclinical CHD based on noninvasive imaging and was linked to characteristics of the insulin resistance, or the metabolic syndrome.