The effect of comorbid alcoholism on recurrence in affective disorder: a case register study

Background: Studies of the effect of comorbid alcoholism on the risk of recurrence in affective disorder have given contradictory results. Method: Using survival analysis, the rate of recurrence was calculated in a case register study including all hospital admissions with primary affective disorder in Denmark during 1971-1993. The rate of recurrence was estimated following each new affective episode. Results: In all, 20 350 patients were discharged after first admission with a main diagnosis of affective disorder of depressive or manic/circular type. Among these, 518 patients (2.6%) had an auxiliary diagnosis of alcoholism. Patients with a current auxiliary diagnosis of alcoholism had increased rate of recurrence following the first three affective episodes but not following subsequent episodes compared with patients without auxiliary diagnoses. The effect of alcoholism declined with the number of episodes. In contrast, no effect was found of other auxiliary diagnoses on the rate of recurrence. Conclusion: Rehospitalisation data suggest that concurrent alcoholism increases the risk of recurrence of affective episodes during the initial course of unipolar and bipolar disorder but has no effect on recurrence later in the course of the illnesses. Limitation: The data relate to re-admissions rather than recurrence. Clinical relevance: The study emphasises that alcoholism has a deteriorating effect on the course of affective disorder. (C) 1999 Elsevier Science B.V. All rights reserved.