Inter-rater reliability of the French version of the core index for melancholia.

BACKGROUND: Assuming that psychomotor disturbances represent the core and are specific of melancholia, Parker et al. have developed the CORE, an 18-item scale assessing retardation, agitation and non-interactivity by behavioural observation which is able to distinguish melancholia from other depressive disorders. We report an inter-rater reliability study of the French version of the CORE.

METHODS: 35 French-speaking in-patients, with ICD-10 criteria for major depression underwent a video-recorded interview aimed to rate the CORE. Each patient's recording was rated by 5 psychiatrists. We tested the inter-rater reliability of the total CORE score and of each of its three subscales' scores using the intra-class correlation coefficient (ICC). A cut-off score for melancholia was established against the opinion of the psychiatrist in charge of the patient using a ROC curve. We used Cohen's kappa to assess the agreement between raters as to rate patients above the cut-off, namely the allocation of melancholia.

RESULTS: The global ICC for the total score was 0.88 and ranged from 0.97 to 0.75 for the varying rater dyads. A ROC curve yielded an optimal cut-off of 5 for melancholia. The global kappa for the agreement on melancholia allocation was good (0.65).

LIMITATIONS: The five raters had not exactly the same condition of quotation. The agreement for the "agitation" subscale was poor.

CONCLUSION: The French version of the CORE, has a good to excellent inter-rater reliability for the total score as for the allocation of melancholia according to a cut-off. Further validation studies are required to allow research application.