Josephine van Dongen

2 Acute gastroenteritis disease burden among infants with medical risk conditions 35 Discussion In this prospective cohor t study we quantified the AGE disease burden among infants with medical risk conditions on several items; incidence, severity, healthcare attendance and family impact. For community AGE we found an IR of 73.5 per 100 PY, translating to at least one AGE episode in the first 18 months of life in medical risk infants. One in three AGE episodes required a doctor visit and one in thir teen required hospitalization. One third of episodes were classified as severe. In addition to the AGE disease burden incurred by the infant, we observed substantial societal burden. In 30% parents and ill infants were absent from paid work or daycare, respectively, in 40% families couldn’t fulfill their normal activities. Rotavirus and norovirus accounted for one third of all AGE episodes and rotavirus positive AGE was associated with more severe disease. In line with this, AGE episodes occurring during seasonally active months for rotavirus and norovirus were associated with more severe disease. We hypothesized that the burden of disease of AGE in medical risk infants is higher compared to healthy infants, because it is suggested that severe childhood infections are more prevalent 24,25 and harm these infants more 26 . However, the overall AGE IR found in our study is in line with repor ted IRs for healthy infant populations in the Netherlands. DeWit and colleagues found an IR of 74 per 100 PY in a population based setting for 0-1 year olds, and of 90 per 100 PY for 1-4 year olds 27 . Another Dutch community study (RotaFam) even found a three times higher all- cause AGE IR (301/100 PY in children up to two years of age) 28 , but this study was conducted during the high epidemic months only (January-May). In our study, the incidence of AGE was also twice higher during the seasonal months compared to the off-season months. Fur thermore, the RotaFam study used an interactive mobile application to monitor real-time AGE symptoms, which may have yielded higher case-ascer tainment than in our study which relied on active repor ting by parents and recording on monthly questionnaires. These IR comparisons suggest that medical risk infants do not have higher IRs compared to healthy infants. Compared to studies among healthy infants, we found that AGE healthcare attendance and severity appear to be increased among medical risk infants. In our study, 51% of infants required healthcare related to AGE, whereas this propor tion was only 18% in a Dutch community study among 1523 healthy infants 10 . Moreover, 7.5% of AGE episodes among medical risk infants required hospitalization in our study, compared to 3.4% and 1.6% respectively, in British and Dutch studies among healthy infants with AGE 10,29 . Similarly, our findings suggest increased severity and prolonged duration of symptoms among medical risk infants with 27% of episodes classifying as severe compared to 8% in healthy infants and a median symptom duration of 5 days versus 3-4 days in healthy infants 28,30,31 . These findings are in contrast with the statement recently published by the EuropeanAcademy of Pediatrics 32 , suggesting no accountable evidence on increased severity in specific risk groups. Based on our study we conclude that the disease burden of AGE among medical risk infants is substantially increased relative to healthy infants.