Josephine van Dongen

Chapter 3 78 Supplementary Material Additional file 1: Model Input Data Table S1 – Assumed herd protection effects for vaccinated and unvaccinated age cohorts Vaccinated Unvaccinated Age group Study estimates Source Model input Study estimates Source Model input <2-3 months 61% 1,2 30% NA 0 3 mo -1 year 37-65%* 3 25% NA 1-5 0 1-2 years 37-65%* 25% 33-72% 28% 2-3 years 37-65%* 25% 38-62% 28% 3-4 years 37-65%* 25% 36-65% 28% 4-5 years 37-65%* 25% 25-65% 28% 6-10 years NA 0 39-61% 25% 10-14 years NA 0 50-55% 25% * age-group not specified, average of ages < 5 Intussusception length of hospital stay Administrative hospital discharge data were retrospectively collected from the Dutch National Medical Registration (LMR) database.The LMR database covers around 90% of the total Dutch population of 17 million people. It contains anonymized data on hospital admissions, outpatient consultation and emergency depar tment visits including discharge diagnoses according to the International Classification of Diseases (ICD) codes, date of admission and discharge, patient age and gender. For diagnostic coding, the Ninth Revision (ICD-9) was used up to 2012 and ICD-10 thereafter. A validation study showed high accuracy of coding and concluded that the discharge data are generally of high quality 6 . For the period from 1 January 2008 to 31 December 2012, we extracted all cases with a primary or secondary discharge diagnosis of intussusception (ICD-9 CM code 560.0) in children aged between 0 and 12 months (i.e. children aged 0–35 months).A total of 276 cases were retrieved. The average length of stay was 2.11 days and 95% of patients were discharged within 6 days of hospitalization. For the complicated IS cases, we assumed their hospital stay represented the upper 5% of the length of stay distribution which was > 6 days, 3 times more than the average length of stay. We thus assumed a three times longer hospital stay for complicated IS cases, compared to uncomplicated IS cases. A similar assumption was applied for utility losses, such that QALY losses for complicated IS were three times that of uncomplicated IS.