Clinical variables in pharmacoepidemiology

Pharmacoepidemiology traditionally concerns itself with the rates at which drugs are prescribed and used in the general population. Interpretations of these data frequently assume that the rates--for psychotropic drugs--reflect primarily the reinforcing properties of the drugs. This paper, in contrast, focuses on the influence of certain clinical characteristics of consumers on patterns of psychotherapeutic drug use. The data are from a nationwide (US) probability sample of 3,161 persons aged 18-79 years surveyed in 1979. One-year prevalence rates of use and the longest period of regular daily use serve as indices of drug consumption. Scores on a 43-item checklist of psychological symptoms were used to compute two clinical descriptors of the respondents--a quantitative index of the level of psychic distress and a qualitative syndromal classification including depression, agoraphobia/panic, other phobias, and generalized anxiety. The data showed that, although anxiolytics and antidepressants have characteristic patterns of prevalence and duration of use, the clinical characteristics of users (severity and pattern of symptoms) strongly influence these patterns. Prevalence and duration of drug use alone do not suffice to illuminate the social functions and significance of psychotherapeutic agents, to provide a basis for value judgments about the use of such compounds, and to guide medical decision-making. Since clinical variables play such a major role in the consumption of these agents, it is crucial to include information about these variables in the analysis and interpretation of patterns of psychotherapeutic drug use.