Clinical correlates of atypical depression and validation of the French version of the Scale for Atypical Symptoms (SAS)

BackgroundThe 8-item “Scale for Atypical Symptoms” (SAS) and its structured interview, the SIGH-SAD, have been developed to assess atypical symptoms of depression in winter depression. Although they are commonly used, no validation study has yet been conducted.Methods270 consecutive depressed inpatients were assessed prospectively. Pearson's correlation coefficients between fulfilment of Liebowitz criteria for atypical depression and both the SAS score and the atypical balance [ratio of the AS score to the total score on the Hamilton Depression Rating Scale 29-item (HDRS-29)] were calculated. The SAS was evaluated against Liebowitz criteria using binary logistic regression. A ROC curve was performed with the atypical balance against the fulfilment of Liebowitz criteria.Results18.5% of patients met the criteria for atypical depression. The presence of an atypical depression was significantly correlated with both the atypical score (r = 0.42) and the atypical balance (r =  0.51). The logistic regression showed that a higher score on the SAS, the absence of a somatic syndrome (ICD-10) and a lower HDRS-21 score were independent predictors of an atypical depression while age, gender and bipolarity were not. The ROC curve showed that an atypical balance of 29% was the optimal threshold for the diagnosis of atypical depression (sensitivity = 0.86, specificity = 0.79).LimitationPatients with bipolar I and II were not distinguished.ConclusionAtypical depression is relatively frequent in hospitalised patients. The concurrent validity of the French version of the SAS and its structured interview, the SIGH-SAD is satisfactory.