Background: Hypoalgesia has been identified in patients with DM and hypertension. In addition, endogenous opioid system has been proven to be activated during myoischemia. The aim of the study was to test if pain scales could enhance the diagnostic accuracy of CAD.
Methods: Patients (n=249) with symptomatic chest pain with Myocardial Infarction (MI) suspicion, or with positive stress test were prospectively enrolled for diagnostic coronary angiography by the left trans-radial approach. The pain elicited by arterial puncture was assessed using 3 different pain-scale questionnaires, namely the Numerical Rating Scale (NRS), Verbal Rating Scale (VRS), and Visual Analogue Scale (VAS), immediately after the procedure. The pain scales were compared between patients with CAD and non-CAD to find the associations.
Results: All the values of pain scales, including NRS, VRS, and VAS were significantly lower in patients with CAD (n=138) compared to those without CAD (n=111). The optimal cut-off points (sensitivity/ specificity) of pain scales were 3.25 (0.74/0.75) in NSR, 1.5 (0.69/0.79) in VRS, and 4.25 (0.68/0.78) in VAS. In addition, these three pain scales improved c-statistics for CAD prediction from 0.50 to 0.73~0.75. Patients with low pain scales of NSR 3.25 (or 3) had >8-fold higher risk of CAD than those with NSR>3.25 (or 3).
Conclusions: These findings suggest that low pain scales can enhance diagnostic accuracy in patients with symptomatic chest pain suspicious of MI or with positive stress tests. NSR was the best pain scale among these three for enhancing diagnosis of CAD.