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Keller P F Pagano S Roux Lombard P Sigaud P Rutschmann OT Mach F Hochstrasser D Vuilleumier N (Geneva University Hospitals Geneva). Autoantibodies against apolipoprotein A 1 and phosphorylcholine for diagnosis of non ST segment elevation myocardial infarction. J Intern Med 2011; doi: 10.1111/j.1365 2796.2011.02479.x Objectives. To explore the diagnostic accuracies of anti apolipoproteinA 1 (anti ApoA 1) IgG and anti phosphorylcholine (anti PC) IgM alone expressed as a ratio (anti ApoA 1 IgG/anti PC IgM) and combined with the Thrombolysis In Myocardial Infarction (TIMI) score for non ST segment elevation myocardial infarction (NSTEMI) (NSTEMI TIMI score) to create a new diagnostic algorithm the Clinical Autoantibody Ratio (CABR) score for the diagnosis of NSTEMI and subsequent cardiac troponin I (cTnI) elevation in patients with acute chest pain (ACP). Methods. In this single centre prospective study 138 patients presented at the emergency department with ACP without ST segment elevation myocardial infarction. Anti ApoA 1 IgG and anti PC IgM were assessed by enzyme linked immunosorbent assay on admission. Post hoc determination of the CABR score cut off was performed by receiver operating characteristics analyses. Results. The adjudicated final diagnosis was NSTEMI in 17 (24/138) of patients. Both autoantibodies alone were found to be significant predictors of NSTEMI diagnosis but the CABR score had the best diagnostic accuracy [area under the curve (AUC): 0.88; 95 confidence interval (CI): 0.82 0.95]. At the optimal cut off of 3.3 the CABR score negative predictive value (NPV) was 97 (95 CI: 90 99). Logistic regression analysis showed that a CABR score >3.3 increased the risk of subsequent NSTEMI diagnosis 19 fold (odds ratio: 18.7; 95 CI: 5.2 67.3). For subsequent cTnI positivity only anti ApoA 1 IgG and CABR score displayed adequate predictive accuracies with AUCs of 0.80 (95 CI: 0.68 0.91) and 0.82 (95 CI: 0.70 0.94) respectively; the NPVs were 95 (95 CI: 90 98) and 99 (95 CI: 94 100) respectively. Conclusion. The CABR score derived from adding the anti ApoA 1 IgG/anti PC IgM ratio to the NSTEMI TIMI score could be a useful measure to rule out NSTEMI in patients presenting with ACP at the emergency department without electrocardiographic changes.