A first diagnosis related to psychiatry and substance abuse was found in 2.7% of all events at the casualty clinics, and the most frequent diagnoses were due to substance abuse, depression/suicidal behaviour, or anxiety. The prevalence of P-diagnoses was relatively constant throughout the ages 15–59 years and almost absent in patients younger than 15 years. The data were collected at two casualty clinics representing different organizational models. The total rate of events in the two clinics differed, possibly due to differences in availability of rGPs and daytime attendance at the casualty clinic. However, the findings from the clinics were similar regarding use of diagnoses from the chapter P of ICPC-2, suggesting that the results might be generalized to Norwegian casualty clinics. The main findings also compare well with numbers previously reported from out-of-hours services 
ICPC-2 is not unambiguous for classification of symptoms and diseases. We have probably missed some cases of deliberate self-harm, intoxication, and anxiety presented as physical symptoms, thus somewhat underestimating the actual prevalence. We focused on first diagnosis. By convention, the dominant problem reported by the patient is written first. Due to concurrence of P-diagnoses, to include the events with a P-diagnosis as second diagnosis would have been deceptive regarding age and gender distribution of the patient group. Adding P-diagnoses given as second diagnoses would also have overestimated the actual proportion of events given a diagnosis from the chapter P when compared with other chapters in ICPC-2.
The events were registered retrospectively by searching diagnoses filed in the billing cards in the computer software. The billing cards are usually written at the end of the patient–doctor contact. Hence, the time registered for initiating the billing card gives a good estimate for time of contact with the patient.
We found that psychiatric diagnoses are seldom given at casualty clinics, although they are more frequent in out-of-office events than in consultations. Other studies have shown that approximately 5% of home visits are caused by psychiatric problems 
, figures comparable to our finding of 8.4% of all out-of-office events. Out-of-office events often have a higher priority grade due to higher urgency of the medical problem. The higher prevalence in out-of-office events may therefore indicate that out-of-hours services play an important role in emergency psychiatric care.
Even if the P-chapter was relatively seldom used, it was used approximately as much as the chapter covering cardiovascular problems. A study of Norwegian out-of-hours services found that the lowest priority grade was given in a minimum 65% of the encounters 
, of which a major proportion would receive respiratory and musculoskeletal diagnoses. Another study showed that acute psychiatry is among the emergency situations most commonly experienced by GPs participating in Norwegian out-of-hours services 
. Nearly all GPs (92%) had experienced at least one emergency situation related to psychiatric illness during the last year. In addition, 69% had experienced an intoxication or overdose. This might imply that even if the P-diagnoses are seldom used, the urgency of the problems presented may be high.
The majority of out-of-office events with P-diagnoses appeared in the age group 15–29 years. This probably reflects the young adulthood onset of most psychiatric diseases. In addition, binge drinking and use of illegal drugs are more common among young people, and this may create a need for medical help and also indirectly contribute to the need for acute care by destabilizing well-managed psychiatric illness.
We found gender differences in the subgroups of substance abuse and anxiety. Men between 15 and 45 years accounted for 56% of the total number of patients receiving substance abuse-related diagnoses, probably reflecting the higher prevalence and more aggressive behaviour related to substance misuse among men. Diagnoses related to anxiety were more common among women than men, which might reflect both differences in prevalence of the disease and a possible higher tendency among men to report anxiety as a physical symptom.
The fact that events due to psychiatry are relatively more common during the night and particularly prevalent during July (a holiday month), might reflect the importance of the casualty clinics as a supplement when the regular GPs and professional psychiatric services are unavailable. Opening hours of psychiatric healthcare may also not be adapted to these patients’ needs, a viewpoint shared by psychiatric specialists 
In conclusion, psychiatric and substance misuse-related problems are relatively seldom presented at casualty clinics in Norway, but their prevalence seems to increase at times of decreased availability of primary and specialist psychiatric healthcare. Alcohol plays an important role as contributor to the contacts with casualty clinics, especially during the night and at weekends. Further research is needed to establish the appropriateness and quality of the services at casualty clinics.