Alcoholism treatment episodes validly defined using mental health care utilization records

We propose a method for defining and empirically validating episodes of alcoholism treatment from health care utilization records.

The study includes utilization records from 86,207 patients enrolled in a large managed behavioral care company who had at least one alcoholism encounter between 1991 and 1998. Treatment episodes are defined as a minimum number of alcoholism treatment encounters with the behavioral care company prior to a "clear zone" of no encounters. Statistical procedures to select a subset of episode definitions from a number of candidate definitions and methods for assessing the convergent and criterion validity of the definitions are presented.

The percentage of patients having at least one episode of alcoholism treatment varies from 43% to 77%, with the results being more sensitive to the minimum number of encounters required than the length of the clear zone. Criterion validity does not reveal any clear "winning" definitions; positive predictive ability increases most rapidly when going from 2 to 3 encounters required.

The most robust definitions of an alcoholism treatment episode entail 3 to 4 encounters with a clear zone of 3 to 4 months.