3.1
The use of extended sources of information is an important part of the diagnostic process, since they corroborate, complement or correct information provided by the patients themselves.
3.2
Sources of information relevant to the diagnostic enterprise should be selected according to the objectives of the evaluation and the setting where it is taking place (school, emergency room, police station, or detention centre, for example). Normally, the minimum standard would be to consult the records of any previous treatment and to contact one relevant person.
3.3
The use of extended sources is essential in circumstances that prevent the patient from providing adequate information: in the emergency room, when the patient is too young or too old, or when the patient is in a psychotic state, intoxicated or unconscious.
3.4
The type of data to be collected through extended sources of information varies according to the patient's individual circumstances. Developmental history, family history, diagnoses made during previous hospitalisations, and current functioning are examples of data that frequently the patient is unable to provide fully and must be obtained from other sources.
3.5
The need to use other sources of information should be discussed with the patient, whose consent should be requested whenever possible and in accordance with cultural norms. Specific thoughts and feelings that the patient might have about these sources should be explored. The patient should be assured of confidentiality to the fullest extent possible. This may be crucial in circumstances where revealing a family secret might have serious consequences for the relationship with the patient's primary support group. Whenever confidentiality on the part of the clinician cannot be complete, this should be made explicit.
3.6
If the patient is a young child, the clinician should interview the parents, other caregivers, teachers, youth-camp counsellors, school psychologists, paediatricians, other relatives, and anyone else who can provide information about the current behaviour and functioning of the child, as well as the child's psychosocial functioning and adaptation.
3.7
Information from other sources should be treated with the same thoughtful and critical attitude used for information provided by the patient. One must remember that information offered by other sources is not the ultimate truth about the condition of the patient, but a different perspective, and it might be in fact another source of unreliability. Clinical judgement and experience should be employed to detect sources of unreliability, and to weigh the diagnostic value of all collected data.
3.8
Confidentiality should be assured to the person giving information, to the fullest extent permissible by law and local customs. One must be aware that the informant could be involved in a conflictual relationship with the patient.
3.9
The patient's records and the records of relatives, as well as judicial, social, counselling and educational records, are all useful documentary sources of information (Fig. 3.1). Usually the consent of the patient is necessary to consult these sources.
Fig. 3.1 Use of extended sources of information.
3.10
Past records may be helpful but they should be reviewed with a critical attitude. For example, when using old records one must be attentive to diagnostic practices prevalent at the time the record was prepared: for instance, bipolar disorder or borderline personality disorder could have been erroneously diagnosed as schizophrenia.
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