Considerations on the ICD-11 classification of psychotic depression.

were too vague to merit a further distinction between the two entities than that defined by the DSM-III-R (psychosis designated by a qualifying decimal point under the severity code) [17] . Therefore PD remained classified under severe depression in both the DSM-IV and the ICD-10. During the DSM-IV/ICD-10 era a number of studies reporting significant differences between PD and nonPD have been published (for a review, see Rothschild [10] ). Consequently, the discussion regarding the classification of PD goes on [18, 19] and is of the utmost importance at a time when the current diagnostic manuals are under revision [20, 21] . Below, we discuss the arguments in favour of and against classifying PD as a distinct syndrome under the affective disorders. In order to cover all aspects, the discussion will build upon the five criteria for the ‘valid psychiatric syndrome’ as defined by Robins and Guze [22] – here accompanied by a sixth criterion covering ‘treatment response’. Finally, based on this evaluation of the current evidence, we give an outline for a redefinition of PD for the upcoming 11th revision of the International Classification of Disease (ICD-11), which is due in 2015. Introduction