Objectives - (I) To review the studies which investigated the frequency of psychiatric disorders among primary care attenders, using a standardized psychiatric interview as the case finding instrument; (II) to discuss the factors possibly explaining the different results found; (III) to highlight the central role of international multicenter collaborative studies, carried out in primary care settings. Method - the studies were reviewed, which were published in international journals between 1970 and 1993. The studies were located through a computerized search of the databases MEDLINE and Psychological Abstracts; in addition, the reference lists of the studies located in this way were examined and international journals were manually scanned in order to avoid possible omissions. Finally, the annotated bibliography, edited by Wilkinson (1985), was examined, since it included the studies having psychiatric focus, carried out in primary care and published between 1977 and 1985. Results - Thirty papers were traced, but 9 were excluded since they duplicated results or because of methodological limitations. So far, the overall frequency of psychiatric disorders among primary care attenders has been investigated using standardized procedures in 13 countries only. The frequency of psychiatric disorders ranged between approximately 10% and 50%. The possible reasons accounting for the differe- nces between the studies were discussed in the light of three factors: I) the research design and study characteristics; II) the reliability and comparability of different diagnostic categories and classificatory systems; and III) the different organization of health services across countries. Conclusions - In the light of the difficulties faced when the findings of independent studies, carried out in different countries or even in the same country, are compared, the central role of in- ternational multicenter collaborative studies conducted in this field is suggested.

Objective - To discuss some theoretical and practical problems related to classification in the medical and psychiatric fields, and to present the general structure of the Tenth Revision of the International Classification of Diseases (ICD-10), officially adopted as from January 1993. Results - This paper discusses the epistemological basis of classification, the various classification strategies adopted in the medical and psychiatric fields and the main theoretical models employed in this area. The problems related to the reliability and validity of psychiatric diagnoses are then reviewed, and the different strategies to be used in order to improve them are presented. Finally the principles which have led the development of the ICD-10, and the field trials carried out in order to test the appropriatness of this system are discussed. Conclusions - In the psychiatric field classification is essential in order to make possible an ordered systematization of new knowledge and to facilitate the communication between health workers and users of services. The ICD-10 represents the biggest effort ever carried out at an international level to build a reliable classification incorporating different psychiatric traditions.

Objective – The study of the relation between treatment costs and disability of psychiatric patient groups. Design – Perspective assessment of costs and disability of 1371 adult psychiatric patients in charge at two Operative Psychiatric Units (OPU), followed during an average period of 9 months. Data are related to all OPU's psychiatric services, including ambulatory, full or half-residential and psychiatric departments of acute hospital services. Setting — OPUs of Magenta (MI) and Desio (MI). Methods – The disability level has been measured by Health of the Nation Outcome Scales (HoNOS) filled in at the inclusion of the patient in the study and every three—months on average thereafter. Besides other HoNOSs have been filled in both at admission and discharge from psychiatric departments of acute hospitals, Residential Centres of psychiatric Therapies and Rehabilitation and Guarded Communities. All patients have been grouped using the main psychiatric diagnosis (first digit ICD—10) and the maximum disability level shown in the whole period of the study. Direct costs of publicly financed psychiatric services have only been considered. Their attribution to each patient has been made applying standard costs or tariffs (diagnostic procedures) to the data perspectively collected by the regional Register and a purposely designed protocol. Results – Total cost of 1371 patients has been 9771.1 million lire with a cost per patient of 7127000 lire (sd 19499000) and a cost per «day in charge» of 27172 lire (sd 68358). The cost per day has been found unrelated with the length of observed time frame. At the inclusion the mean level of disability has been 4.26 points (sd 3.73) and 3.19 points (sd 3.26) at the end of the study. Its value, measured at maximum level shown by each problem in the whole period of study, has been 6.00 points (sd 4.64). Disability and treatment cost of each patient did result directly related (r = 0.626, p = 0.0001). All patients have been grouped in 12 classes with a significant (p = 0,0001) overall difference on both their disability level and treatment cost. Conclusion – All adult psychiatric patients could be grouped in disability related classes which sometimes have also a different treatment cost. A study on a greater number of patients is needed to confirm these results. It may also provide a more reliable basis for a new financing system of psychiatric services.

Scope - To discuss, after a description of the main attempts of classification of schizophrenic disorders made from the last century up to now, the main features of the ICD-10 classification of schizophrenia and related dis-orders. The main features of this chapter of the ICD-10 are then compared to the ICD-9 and DSM-III-R classifications. Results - The ICD-10 diagnostic criteria for schizophrenia require a duration of only 1 month (compared to the 6 month duration criterion of the DSM-III-R); positive symptoms of psychosis, in particular Schneiderian symptoms, are given more prominence than they are in the DSM-III-R. Moreover, it is foreseen the possibility of a favourable outcome of the disorder; this has been based on the results of several follow-up studies, including some major WHO multicentric studies showing a positive outcome in substantial proportion of patients. Conclusions - On the whole, ICD-10 broadens the diagnostic concept of schizophrenia in comparison to other diagnostic systems, whereas the emphasis placed on Schneiderian first-rank symptoms tends to overweight this tendency and makes the criteria for inclusion more narrow.