ABSTRACT
Along with the use of diagnostic criteria, there has been a gradual narrowing of definitions of disorders to reduce within-category heterogeneity and improve reliability. This effort to improve within-category homogeneity has led to a problem of poor coverage. That is, many cases typically referred for consultation cannot be classified into clearly defined categories using either system. Two strategies have been adopted to deal with the poor coverage problem. The first is to include an undefined subcategory for many disorders to accommodate individuals who show constellations of symptoms which fall between two clearly defined clinical syndromes. In the DSM such categories are labelled not otherwise specified (NOS) and in the ICD the term unspecified is used, for example, conduct disorder, unspecified. The second solution to the coverage problem has been to include a list of problems, concerns and factors that may lead to referral but which fall outside the overall diagnostic framework. In the ICD system these are termed Z codes and in the DSM, they are referred to as V codes. For example, in the ICD 10, code Z64.0 is used when a person has problems related to unwanted pregnancy. In DSM IV TR, code V61.20 is used if there is a parent-child relational problem.
