A 1998 study of 12 inpatient alcoholism treatment facilities for U.S. Navy personnel yielded similar results (Trent 1998). A planned reduction from a 6-week to a 4-week treatment program allowed researchers to conduct a natural experiment of treatment outcomes under the two plans. Patients treated in the 4-week program achieved outcomes similar to those treated in the 6-week program. The researchers also noted that participation in aftercare (principally attendance at AA) was the best predictor of treatment outcomes at 1-year follow-up.
