Clinical trials (CT) are the main scientific support of the recommendations of pharmacological treatment of patients with schizophrenia. However, CT tend to strengthen the internal validity at the expense of external validity and the ability to generalize the results to the clinical population. For this reason, in recent years have developed large practical clinical trials that expand the inclusion criteria to incorporate as many real patients as possible. The first and most significant of these trials was the CATIE study (Lieberman et al, 2005).

To analyze eligibility for participation in CATIE of patients admitted during 2009 in a psychiatric inpatient unit with a diagnosis of schizophrenia.

A total of 145 patients (27.6% females, mean age 39.6+/−12.8 years), consecutively admitted to an inpatient psychiatric ward with a clinical diagnosis of schizophrenia were assessed to test if they would fulfill criteria for participation in CATIE.

60 (41.4%) patients did not fulfill CATIE inclusion criteria. Mental retardation (n = 22, p < 0.001), absence of informed consent (n = 15, p < 0.001) and refusal to take oral medication (n = 12, p < 0.001) were the main factors responsible for not meeting inclusion criteria.

Meeting the criteria was not significantly related to gender or specific diagnosis.

41.4% of patients admitted to a psychiatric inpatient unit with a diagnosis of schizophrenia did not meet criteria for participation in the CATIE study.