Delusional disorder is a mental illness in which delusions are the dominant symptom. Delusional disorder is not well studied relative to other psychotic disorders - it is poorly understood in practically every aspect of its nature, including cause, phenomenology, prevalence, comorbidity, course, treatment, and prognosis.

To study the clinical and sociodemographic characteristics of individuals admitted for inpatient treatment with the diagnosis of delusional disorder, in particular the adherence to treatment.

Retrospective observational study of inpatient treatment of patients with delusional disorder diagnosis between january 1st2007 and 31th december of 2017 in the Psychiatry Service of CHUSJ. Follow up of 2 years from discharge. Data collected included sociodemographic characteristics and clinical features. Descriptive analysis of the results was performed using SPSS (v.26).

In the period of time analyzed, 152 hospitalizations were identified, corresponding to 114 patients: 38.2% male and 62.8% female. The average age was 58 years. 3 months after discharge: 65% of patients were going to the medical appointments, which dropped to 60% in 6 months, 55% in 12 months, 53% in 12 and 24 months. Regarding adherence to the treatment: 65% of patients were still adherent to medication in 3 months time, 55% in 6 months, dropping to 50% in a year and to 48% in 2 years. There is a relation between involuntary discharge and adherence to consultations and medication.

A cardinal characteristic of delusional disorder, conviction that one is not mentally ill, contributes complexity to the treatment challenges and profoundly affects the therapeutic relationship.