Predictors of recurrence in affective disorder. A case register study.

BACKGROUND: The risk of recurrence in affective disorder is affected by socio-demographic variables such as gender, age at onset and marital status and by illness related factors as the length of previous episodes and the total duration of the illness. The present study investigated how the effect of these variables changed with the progression of the illness.
METHOD: Using survival analysis, the risk of recurrence was estimated in a case register study including all hospital admissions with primary affective disorder in Denmark during 1971-1993.
RESULTS: Totally, 20350 first admission patients had been discharged with a diagnosis of affective disorder, depressive or manic/circular type. Initially in the course of the illness, bipolar patients had a substantial greater risk of recurrence compared with unipolar patients. At this time, gender, age and marital status together with the total duration of the illness predicted the risk of recurrence in both unipolar and bipolar illness. Some variables had different predictive effect in the two types of illness. Later, especially the duration of the previous illness predicted the risk of recurrence.
CONCLUSION: It seems as initially in the course of affective disorder socio-demographic variables such as gender, age at onset and marital status act as risk factors for further recurrence. Later, however, the illness itself seem to follow its own rhythm regardless of prior predictors. LIMITATION: The data relate to re-admissions rather than recurrence and the findings may be due to decreasing sample sizes during the course of illness. CLINICAL RELEVANCE: The study underscores the importance of the illness process itself.