Development of a short form of the Cardiac Distress Inventory

A total of 405 participants reporting an acute coronary event in the previous 12 months was recruited from three hospitals, through social media and by direct enrolment on the study website. Participants completed an online survey which included the full version of the CDI and general distress measures including the Kessler K6, Patient Health Questionnaire-4, and Emotion Thermometers. Relationship of the CDI with these instruments, Rasch analysis model fit and clinical expertise were all used to select items for the short form (CDI-SF). Construct validity and receiver operating characteristics in relation to the Kessler K6 were examined.

The final 12 item CDI-SF exhibited excellent internal consistency indicative of unidimensionality and good convergent and discriminant validity in comparison to clinical status measures, all indicative of good construct validity. Using the K6 validated cutoff of ≥ 18 as the reference variable, the CDI-SF had a very high Area Under the Curve (AUC) (AUC = 0.913 (95% CI: 0.88 to 0.94). A CDI-SF score of ≥ 13 was found to indicate general cardiac distress which may warrant further investigation using the original CDI.

The psychometric findings detailed here indicate that the CDI-SF provides a brief psychometrically sound screening measure indicative of general cardiac distress, that can be used in both clinical and research settings.