A small subset of patients with above average admissions to psychiatric inpatient units is recognized in clinical practice. These frequent users tend to be younger and to have a diagnosis of schizophrenia or affective disorder. Social conditions and the severity of the illness seem to be associated with this increased number of admissions.

To study demographic and clinical characteristics of frequent and non-frequent users of a psychiatric inpatient unit.

Retrospective data of all the patients admitted to a psychiatric inpatient unit from January 2004 to December 2008 were reviewed. Frequent-users were defined as patients with 3 or more admissions over that period of time, and non-frequent users as those with less than 3 admissions. The two groups were compared in terms of age, gender, ethnicity, psychiatric diagnosis and compulsory admissions

In a total of 2018 admissions and 1348 patients, the frequent-user group represented 10.2% (n = 137) of the patients and 28.9%(n = 584) of the admissions. Frequent-users were significantly younger (39.5 vs. 44.5 years, p = .001), more frequently black (22.6 vs. 19.4%, p < .001) and compulsorily admitted (27.7 vs. 14%, p < .001) than non-frequent users. Patients with bipolar disorder (p = .001), schizophrenia (p = .003) belonged significantly more to frequent-users group, while unipolar depressive patients (p = .016) and other diagnosis (p = .011) was more significantly represented in the non-frequent users group. Frequency of admission did not differ with gender.

The results concerning age and psychiatric diagnosis are consistent with previous studies. Compulsory admissions and black ethnicity were significantly higher among frequent- users.