1. The Research Question
Has this patient with chest pain coronary artery disease? Diagnostic utility of a clinical decision rule. J Haasenritter, S Bösner, N Donner-Banzhoff (Philipps University Marburg, Germany)
Question: What is the diagnostic utility of the Marburg Heart Score (MHS) in terms of improving the accuracy of the GP‘s initial clinical diagnosis?
Why this is important?
GPs must identify patients with CAD while avoiding unnecessary testing and hospital admissions in the large majority of patients with non-cardiac pain.
The Marburg Heart Score (MHS) is an easy to use, valid, and robust tool for ruling out CAD in chest pain patients. (Bösner et al. 2010, Haasenritter et al )
Its impact on improving the GP’s initial clinical diagnosis is unclear.
CA22: Has This Patient With Chest Pain Coronary Artery Disease: Diagnostic Utility of a Clinical Prediction Rule. (Oral Presentation On Completed Research) Joerg Haasenritter; Stefan Boesner; Erika Baum; Norbert Donner-Banzhoff (Philipps University Marburg, Department of General Practice/ Family Medicine, Germany)
Cited references:
Bösner S, Haasenritter J, Becker A, Karatolios K, Vaucher P, Gencer B, Herzig L, Heinzel-Gutenbrunner M, Schaefer JR, Abu Hani M, Keller H, Sönnichsen AC, Baum E, Donner-Banzhoff N. Ruling out coronary artery disease in primary care: development and validation of a simple prediction rule. CMAJ. 2010;182(12):1295–300.
Haasenritter J, Bösner S, Vaucher P, Herzig L, Heinzel-Gutenbrunner M, Baum E, Donner-Banzhoff N. Ruling out coronary heart disease in primary care: external validation of a clinical prediction rule. Br J Gen Pract J R Coll Gen Pract ;62(599):e415–421.

2. What the Researchers Did
Population/Subjects: 832 consecutive patients aged ≥ 35 years presenting with chest pain in primary care/56 general practitioners (GPs)
Design: Comparative diagnostic accuracy study
Basic Method/Intervention
Comparative test: GP’s unaided clinical judgment based on history and physical examination.
New/ index tests: 1) Marburg Heart Score (MHS); 2) GP’s aided clinical judgment based on history, physical examination and results of the MHS; 3) Using the MHS as a triage, only patients with a score value of 3 were further assessed by GPs.
Reference diagnosis was established using a delayed-type reference standard in combination with an independent expert panel.
Authors compared 3 index tests, all three based on using the MHS, with the GPs’ unaided clinical judgment (comparative test).
Comparative test
Unaided clinical judgment: GPs were not aware of the MHS and rated the probability of CAD as the underlying cause of the chest pain.
Index tests:
MHS: The probability of CAD was determined based on the MHS alone.
Aided clinical diagnosis: GPs calculated the MHS and combined the results with their own assessment.
Triage: The MHS was used as a triage test. GPs assessed only patients with an intermediate MHS score.

3. Marburg Heart Score (MHS)
Easy to use, valid and robust tool for ruling out CAD in chest pain patients
Item
Value
Age
female≥65, male≥55
1 P
Known vascular disease (CAD, stroke, PAD)
Pain worse
during exercise
Pain not reproducible
by palpation
Patient assumes
pain is of cardiac origin
Score
Probability of CAD
0-2 points
2.3% (1)
2.1% (2)
3-5 points
39.6% (1)
23.3% (2)
Cited references:
Bösner S, Haasenritter J, Becker A, Karatolios K, Vaucher P, Gencer B, Herzig L, Heinzel-Gutenbrunner M, Schaefer JR, Abu Hani M, Keller H, Sönnichsen AC, Baum E, Donner-Banzhoff N. Ruling out coronary artery disease in primary care: development and validation of a simple prediction rule. CMAJ. 2010;182(12):1295–300.
Haasenritter J, Bösner S, Vaucher P, Herzig L, Heinzel-Gutenbrunner M, Baum E, Donner-Banzhoff N. Ruling out coronary heart disease in primary care: external validation of a clinical prediction rule. Br J Gen Pract J R Coll Gen Pract ;62(599):e415–421.
Bösner et al. CMAJ 2010;182:1295
Haasenritter et al. Br J Gen Pract. 2012;62:e415

4. What the Researchers Found
The figure shows the sensitivity and specificity of the comparative test (unaided clinical judgment) and each index test (MHS, aided clinical judgment, triage), and the difference in both measures for each comparison between the comparative test and one of the index tests.
The specificity of the unaided clinical judgement was 61% and the sensitivity was 83%. Compared to that the MHS had a similar specificity but a higher sensitivity. The Confidence intervals of the differences indicated that these differences were not significant.
The specificity of the aided clinical judgement was 67% and the sensitivity was 91%. Compared to the unaided clinical judgment the aided clinical judgment had both, a higher specificity and sensitivity. However, again the confidence intervals of the differences indicated that these differences were not significant.
The specificity of the triage was 73% and the sensitivity was 81%. Compared to the unaided clinical judgment the triage had a significant higher specificity and a similar sensitivity.
Summary
1. The performance of the MHS was at least equal to that of the unaided clinical judgment. Strictly spoken we have not conducted a non-inferiority study, but looking at the confidence intervals of the differences this conclusion seems to be reasonable. Considering the simplicity of the MHS, this result is remarkable.
2. We found evidence that using the MHS as a triage test can improve the accuracy of the family doctor’s clinical diagnosis.
3. Integrating the MHS into the clinical reasoning seems also to be a promising approach. The differences that we found were not significant.- However, this was a secondary analysis and the study was not adequately powered for this analysis. For example, the power to detect the difference of 8% in sensitivity between the aided and unaided clinical judgment was 14%.

5. What This Means for Clinical Practice
Results of the current study suggest that using the MHS may improve the accuracy of the GP’s clinical diagnosis.
Considering also other aspects of the MHS (simplicity) and previous study results (validity, robustness) we recommend the MHS as a useful tool for ruling out CAD in chest pain patients in primary care.
We found evidence that using the MHS may improve the accuracy of the GP’s clinical diagnosis and that it be suitable for initial triage in a primary care setting.
Limitations:
- Misclassification bias  We cannot consider our reference standard to be perfect. However, it was the best available reference standard.
- Review bias  Reference panel was not blinded to results of the index tests. On the other side, we have no reason to assume that this affected the accuracy of the single tests in different ways, so one can assume the comparisons to be unbiased.
- Selection bias  No randomized allocation of GPs to different groups. This would only affect the comparison between the aided and the unaided clinical judgment (unpaired design), while the other comparisons are based on a paired design.
- Secondary analysis  not adequately powered to detect clinically relevant differences between tests. Our results must be confirmed in an adequately designed study. Considering the factors that determine the sample size it becomes clear that such a confirmation study would require thousands of patients and therefore we are very pessimistic that such a study will ever be conducted. So this is the evidence we have to rely on.