Validity of the MacAndrew scale in a general medical population

The Minnesota Multiphasic Personality Inventory (MMPI) was scored for the MacAndrew (MAC) Scale in a series of samples totaling 14,789 subjects. These samples included 1077 substance-dependent patients (739 men), 7090 selected medical outpatients (2853 men), 5000 unselected medical outpatients (2500 men), 214 psychiatric inpatients (92 men) and 1408 contemporary normal (646 men). Overall, the MAC Scale correctly classified only 70.7% of the men and 37.9% of the women alcoholics. However, when samples of men and women alcoholics were broken down into four age groups, the MAC Scale correctly identified 90% of men alcoholics in the 18- to 24-year age group but only 41% of women alcoholics in the same age group. In addition, the predicted rate of alcoholism in the samples that were not substance-dependent, using the MAC Scale, was approximately 1.5 to 4 times the estimated lifetime prevalence rate (this was also true in the 18- to 24-year age group). MMPI item 215 ("I have used alcohol excessively") correctly identified 95% of the men and 94% of the women alcoholics. It was concluded that, except for men less than 24 years old, the MAC Scale is not an appropriate screening test for substance dependence in a predominantly middle-class medical population.