Clinical presentation of intussusception in Swedish children under 3 years of age and the validity of diagnostic coding.

Purpose: Intussusception has been associated with rotavirus vaccine. The rotavirus vaccine will soon be introduced in the Swedish national immunization program. A validation of the diagnosis of intussusception among Swedish children in the Swedish National Patient Register is needed, as a basis for future vaccine safety surveillance by Swedish registers.

Methods: This diagnostic study reviewed the medical admission records of 392 Swedish children with intussusception from 1987 to 2013. The records were randomly selected by The National Board of Health and Welfare from all Sweden and from both pediatric and pediatric surgery care. Positive predictive values (PPV) were calculated to study the concordance between the diagnosis coded in the Swedish Patient Register and the accepted international criteria of case definitions.

Results: The PPV for a definitive diagnosis, based on certain radiology findings or surgery, was 84%. When clinically probable cases were added the PPV was 87%. When cases of possible intussusception were added the PPV was 89%. The PPV for the 240 children under 1 year was 88%.

Conclusion: Swedish health care registers can be used in the evaluation of incidences of intussusception when rotavirus vaccine will be introduced, due to a high validity of the diagnosis of intussusception in the registers.