Study Reveals Shaken Baby Syndrome Statistics in Scotland

Karen M. Barlow, MRCP (UK) Royal Hospital for Sick Children The cost to society for shaken baby syndrome cases is immense. This high cost was highlighted for me personally in a very emotive way last year at the Third National Conference on Shaken Baby Syndrome in Salt Lake City.

Financially, there is not only the cost of the acute illness, the forensic and police investigations and the judicial process, but since almost 78 percent of survivors have neurodevelopmental abnormalities, there is the cost of the continuing medical and special educational needs of these children1. The cost to the affected families cannot be measured and it is clear that there are more victims than the child himself.

Until now, it has been difficult to accurately assess the effectiveness of educational materials and strategies aimed at preventing shaken baby syndrome. Accurate incidence studies did not exist and without proof of the effectiveness of prevention efforts, it is difficult to get governments to commit to financing these programs.

Non-accidental head injury (NAHI) is a term frequently used to include not only shaken baby syndrome (with or without impact), but also inflicted compression, penetrating and pure impact head injuries. The incidence of NAHI was previously estimated from the incidence studies of subdural haematoma in infancy.

In southwest England and south Wales the incidence of subdural haematoma was 21.0 per 100,000 children under one year of age (95% CI: 7.5 � 34.4) and it was estimated that non-accidental injury accounted for 82 percent of these2.

A 15-year retrospective study in Scotland suggested that an estimated incidence of NAHI of 11.2 per 100,000 children under one year was an underestimate because shaken impact syndrome is not a single coding entity in the international classification of diseases (ICD)3.

We therefore undertook a prospective study to assess the incidence and demography of NAHI in Scotland during 1998 and 1999. We registered all cases by weekly contact with all hospital paediatric departments, paediatric intensive care units and neurosurgical unit admitting children.

Validation was done by 6-monthly questionnaires. A separate search from Information and Statistics Division of the Scottish Health Service using the ICD-10 coding system was undertaken. To ensure that children who died due to NAHI before admission to hospital were not omitted, we searched the Registrar General database for childhood deaths in Scotland. Only anonymous details were obtained.

With these methods we are confident that no cases of NAHI were missed and none doubly recorded. We obtained multicentre and local ethical approval before the study began.

We looked at the incidence and demography of NAHI in a prospective population-based study in paediatric units in Scotland during 1998-99. Shaken baby syndrome occurs with an annual incidence of 24.6 per 100,000 children under one year (95% CI: 14.9 � 38.5).

Cases are more common in urban regions and in autumn and winter months. The risk of a child suffering non-accidental head injury by one year is one in 4,058. These brain injuries occur almost exclusively in young infants. The median age at acute admission was 2.2 months (range: 4 weeks � 8.8 months), younger than the average age of 5 months reported by other series2, and no child was older than 12 months. The age distribution of cases is shown in the figure one on page two of this publication.

A Swedish study concluded that children at risk of child abuse can be identified, and the incidence reduced by legislation banning corporal punishment. Currently the UK, including the devolved parliaments, has issued consultation documents on the law relating to reasonable chastisement - in particular questioning whether shaking children, blows to the head and the physical punishment of very young children should always be unlawful.

At the Third National Conference on Shaken Baby Syndrome, Dr. Mark Dias presented some very exciting results of the Western New York SBS Education Project suggesting that timely parental education is one way to reduce the incidence of SBS.

Our, more precise, measurement of incidence for NAHI in infants less than one year will enable epidemiological surveillance to assess the impact of any future legislative changes and the effectiveness of health education packages in preventing shaken baby syndrome.

References
1. Barlow KM, Thomas E, Minns RA. The neurological and neuropsychological outcome of non-accidental head injury. European Journal Of Paediatric Neurology 1999; 3: 6:A139(Abstract).

2. Jayawant S, Rawlinson A, Gibbon F, et al. Subdural haemorrhages in infants: population based study. BMJ 1998; 317: 1558�1561.

3. Barlow, K. M., Milne, S., and Minns, R. A. A retrospective epidemiological analysis of non-accidental head injury in children in Scotland over the last 15 years. Scottish Medical Journal 43, 1121�14. 1998.