It classifies substance abuse as a biopsychosocial disease and bases its system on the dependence model explained above. This system was set up separate from the DSM classification scheme to eliminate some of the ambiguity of DSM, to avoid being based on any particular theory, and instead to correlate diagnoses with empirical findings. A clinically useful mnemonic for recognizing a pattern of substance abuse is the sequence UCR, which stands for Use, Consequences and Repetition. Abuse, dependence and addiction are characterized by patients who use drugs, experience negative consequences, repeat their use of drugs, incur further consequences, and do not seem able to break the cycle. If this pattern is evident, it is highly suggestive of substance abuse.
Patients are sometimes the last ones to admit their diagnosis of substance abuse.
Denial is often said to be a cornerstone of the diagnosis of addiction, though in the 1990s it has been debated whether such denial has the same meaning as the classical defense mechanism from psychological theory. Patients are sometimes ignorant of the effects of their own substance abuse or will not admit to a problem for fear of negative consequences if their diagnosis becomes known. All too often, substance abusers continue to undergo physical, psychological and social deterioration. In many cases, the disease is fatal. In failing to inform patients of their diagnosis, physicians bypass opportunities to help them get into treatment.