In 1982 Ramsdale et al reported 2 discriminant scores for preoperatively evaluating patients with valvular heart disease for significant coronary artery disease. One goal was to identify patients at low risk for coronary artery disease who would not require coronary angiography prior to surgery. The authors are from the Manchester, England.
The populations consisted of adult patients with valvular heart disease assessed by coronary angiography prior to surgery:
(1) retrospective study: 643 adults with mean age 55 (+/- SD 8)
(2) prospective study: 387 adults with mean age 54.6 +/- SD 9.3)
Discriminant scores developed:
(1) retrospective study
(2) prospective study
Data elements for retrospective score:
(1) history of angina
(2) family history of ischemic heart disease
(3) age
(4) cigarette smoking
(5) mitral valve disease
(6) sex
(7) ECG evidence of myocardial infarction
Parameter |
Finding |
Points |
---|---|---|
history of angina |
no |
0 |
|
yes |
1379 |
family history of ischemic heart disease |
no |
0 |
|
yes |
1250 |
age |
|
84 * (age in years) |
cigarette smoking |
no |
0 |
|
yes |
1068 |
mitral valve disease |
no |
0 |
|
yes |
1162 |
sex |
male |
0 |
|
female |
(-893) |
ECG evidence of myocardial infarction |
no |
0 |
|
yes |
1798 |
retrospective discriminant score =
= SUM(points for all 7 parameters) - 4700
Parameters for prospective score
(1) diastolic blood pressure
(2) total number of cigarettes in life
(3) severity of angina
(4) family history of ischemic heart disease
(5) age
(6) current cigarette smoker
(7) total cholesterol to HDL cholesterol ratio
Parameter |
Finding |
Points |
---|---|---|
diastolic blood pressure |
|
87 * (diastolic blood pressure in mm Hg) |
total number of cigarettes smoked in life |
|
0.0106 * (number of years smoked) * (average number smoked annually) |
severity of angina |
none |
0 * 683 = 0 |
|
on strenuous exertion |
1 *683 = 683 |
|
on moderate exertion |
2 * 683 = 1366 |
|
on slight exertion |
3 * 683 = 2049 |
|
at rest |
4 * 683 = 2732 |
family history of ischemic heart disease |
no |
0 |
|
yes |
1167 |
age |
|
64.6 * (age in years) |
current cigarette smoker |
no |
0 |
|
yes |
997 |
ratio total cholesterol to HDL cholesterol |
|
196.3 * (total cholesterol) / (HDL cholesterol) |
where:
• The simplest method of calculating the average number of cigarettes smoked annually = 365 * (average number smoked daily). If a person's smoking varies widely, then tallying the number may be more accurate.
• "Current" smoking needs to separate people who quit very recently (last week) from those who quit in the near past and the remote past. Regular cigarette smoking in the retrospective study was defined as smoking >= 10 cigarettes a day for >= 10 years within the last 10 years.
• The impact of cigar or pipe smoking is not included in the score.
prospective discriminant score =
= SUM(points for all 7 parameters) - 12058
Interpretation:
• minimum retrospective score: about –3000 (see Figure 2 page 225)
• maximum retrospective score: > +6,000
• minimum prospective score: about –3700
• maximum prospective score: > +17,000
• The prospective score has better performance characteristics than the retrospective score.
Performance characteristics for different breakpoints
Score |
Breakpoint |
Sensitivity |
Specificity |
---|---|---|---|
retrospective |
0 |
100% |
19% |
|
300 |
98% |
26.6% |
|
600 |
95.9% |
36.5% |
|
750 |
95.9% |
42% |
prospective |
0 |
100% |
41.2% |
|
250 |
96.9% |
48.8% |
|
500 |
95.9% |
55.5% |
Prospective Score |
Angiograms Saved |
Patients with Coronary Artery Disease Missed |
---|---|---|
0 |
29.6% |
0% |
250 |
35.9% |
3% |
500 |
40.8% |
4% |
Limitations:
• The scores were developed in 1982.
• The study populations were patients with valvular heart disease severe enough to require valve replacement. Performance of the scores in patients without valvular heart disease would be interesting. Since it based on known risk factors for coronary artery disease, simply adjusting the point assignments might keep it current.
Specialty: Cardiology
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