Diagnosing borderline. A contribution to the question of its conceptual validity.

A total of 437 acute psychiatric inpatients were investigated with the help of a questionnaire containing DSM-III diagnostic criteria for schizotypal as well as for borderline personality disorder and criteria of the Flexible System for the diagnosis of schizophrenia. All patients were also independently diagnosed according to the ICD-9. The clinical ICD-9 diagnoses were compared with the diagnoses given on the basis of the three operational criteria sets mentioned. Patients fulfilling the operational criteria for schizotypal personality disorder were clinically diagnosed as mostly schizophrenic, and there was also a considerable overlap between the two groups of patients, those fulfilling the operational criteria for schizotypal personality disorder and those fulfilling the criteria of the Flexible System for the diagnosis of schizophrenia. Schizotypal personality disorder does not seem to be a clinical entity in the sense of a traditional personality disorder. The majority of patients diagnosed as borderline personality disorder received a clinical diagnosis of a personality disorder. The DSM-III criteria of borderline personality disorder discriminated satisfactorily against schizophrenia as diagnosed by the Flexible System and as diagnosed according to ICD-9. On the other hand, there was no relationship between the borderline personality disorder diagnosis and any single of the ICD-9 personality disorder types. The patients fulfilling the criteria of the borderline personality disorder were equally distributed across all ICD-9 personality disorder types. They were also significantly younger than both the non-borderline and the ICD-9 personality disorder patients. The relationship between borderline personality disorder criteria and age might thus be of a greater relevance than the relationship between these criteria and a clinical type.