Byrne et al ^{Reference Byrne, Power, Boylan, Iqbal, Anglim and Fitzpatrick1} describe a model of a specialist child and adolescent mental health service (CAMHS) which provides 24 hours’ care. We must congratulate them on this unique study and using a model which combines a traditional on-call psychiatric provision with a paediatric liaison model of service delivery. However, we would like to make a few points here and request the authors to clarify three issues for us.

The authors said they were unable to find any published evidence regarding demands on or experience of a 24-hour specialist CAMHS or how in clinical practice in the UK and Ireland service models are implemented. However, a year before the publication of Byrne et al's paper a British study ^{Reference Hillen and Szaniecki2} was published in this journal which highlighted some of the aspects of the service model and analysed the cyclic variations in demand for out-of-hours services in child and adolescent psychiatry, considering it an important factor for service planning. Hillen & Szaniecki's study included 323 individuals recruited from three London teaching hospitals over 4 years and reported that out-of-hours bedside assessments were required in 37% of cases. There were 50% more referrals in the spring compared with the rest of the year but no more referrals than usual during the holidays, a finding which was also seen in Byrne et al's study.

First, we would like to know about the retrospective case study design as it is not clear in the paper and the authors claimed that data were collected prospectively on all presentations during the period reviewed. Second, 52% of the assessed patients required admission in general paediatric wards but there was no information given regarding any psychiatric admission and one would assume that the 7 patients who presented with psychotic symptoms would have been admitted to a psychiatric unit. Finally, we know interdisciplinary liaison appears to carry many advantages but it has both clinical and resource implications, ^{Reference Black, Wright, Williams and Smith3} more so in the current climate where availability of funds is limited. We would be interested to know how the authors dealt with it.