Prevalence of mixed mania using 3 definitions.

OBJECTIVES

Mixed episodes are a combination of depressive and manic symptoms in bipolar disorder (BD). We want to identify the proportion of patients who have depressive symptoms during an acute episode and also the validity of current methods for its diagnosis.

MATERIAL AND METHOD: Cross-sectional multicentre study of patients with type I BD who are admitted to specialized units. 368 patients in 76 centres were included. The patients should have a well established diagnosis of BD and need hospitalisation. The severity of the disorder and clinical status were evaluated upon admission and discharge using CGI-BP-M clinical impression scales, the Hamilton depression scale (HAMD-17) and the Young mania rating scale (YMRS). Upon admission, the necessary criteria for diagnosing a mixed type episode were recorded according to DSM-IV-TR, ICD-10 and McElroy criteria. Clinical judgment of the current type of episode was also recorded.

RESULTS

Prevalence estimations for mixed episodes were: 12.9% according to DSM-IV-TR (n=45), 9% according to ICD-10 (n=31), 16.7% according to McElroy criteria (n=58), and 23.2% according to clinical judgment (n=81). Statistically significant differences were found between the estimated prevalence rates (Cochrane's Q-test, p<0.0001), with the maximum concordance level found between the McElroy and ICD-10 (Kappa=0.66, 95% CI, 0.54-0.77). The DSM-IV-TR criteria only present moderate concordance with ICD-10 (Kappa=0.65, 95% CI, 0.52 to 0.78) and McElroy criteria (Kappa=0.62, 95% CI, 0.50 to 0.74).

CONCLUSIONS

The definition of mixed episodes for BD must be revised to improve consensus and, consequently, therapeutic management. Current diagnostic systems, based on DSM-IV and IDC-10, only capture a limited proportion of patients suffering from mixed episodes, giving rise to important limitations concerning the therapeutic management of BP patients.