Because SUD symptom count shows a continuous and roughly linear association with other measures of substance involvement, a diagnostic threshold will not be determined by finding clear discontinuities in the association of symptom count with external validators. However, this does not mean that the choice of diagnostic threshold is arbitrary. Instead, the threshold should be explicitly designed to avoid what can be considered false-positive diagnostic assignments, and to reflect professional judgments of the importance of diagnosing substance problems at a certain level of severity and the costs of not doing so (Krueger et al. 2004). Choosing the threshold for an SUD diagnosis involves weighing the relative importance and cost of type I and type II errors. When a threshold is higher, there can be concerns about the availability of treatment for those who are subthreshold for a diagnosis, especially with regards to insurance coverage. However, a low threshold can lead to a highly inefficient allocation of scarce and expensive healthcare resources, and stigmatization of individuals lacking meaningful pathology (Room, 2006).
