Validity and reliability of the Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA) in Brazilian bipolar patients.

INTRODUCTION

In Brazil, there is no valid instrument to measure subjective cognitive dysfunction in bipolar disorder. The present study analyzed the psychometric properties of the Cognitive Complaints in Bipolar Disorder Rating Assessment (COBRA) in Brazilian bipolar patients. We further investigated the relationship between the COBRA, objective cognitive measures, and illness course variables.

METHODS

The total sample (N=150) included 85 bipolar disorder patients and 65 healthy controls. The psychometric properties of the COBRA (e.g., internal consistency, concurrent validity, discriminative validity, factor analyses, ROC curve, and feasibility) were analyzed.

RESULTS

The COBRA showed a one-factor structure with very high internal consistency (Cronbach's alpha=0.890). Concurrent validity was indicated by a strong correlation with the cognitive domain of the FAST (r=0.811, p<0.001). Bipolar patients experienced greater cognitive complaints (mean=14.69; standard deviation [SD]=10.03) than healthy controls (mean=6.78; SD=5.49; p<0.001), suggesting discriminative validity of the instrument. No significant correlations were found between the COBRA and objective cognitive measures. Furthermore, higher COBRA scores were associated with residual depressive (r=0.448; p<0.001) and manic (r=0.376; p<0.001) symptoms, number of depressive episodes (r=0.306; p=0.011), number of total episodes (r=0.256; p=0.038), and suicide attempts (r=0.356; p=0.003).

CONCLUSION

The COBRA is a valid instrument to assess cognitive complaints, and the combined use of subjective-objective cognitive measures enables the correct identification of cognitive dysfunctions in bipolar disorder.