Evidence-based referral criteria in growth monitoring

Abstract

Growth monitoring in infancy and childhood has been part of preventive child health programs for more than a century in both developed and underdeveloped countries. It is a popular tool for defining health and nutritional status of children. An important goal of growth monitoring is to identify, at an early stage, genetic disorders, diseases or other conditions that manifest themselves through an abnormal growth. Despite the longstanding and wide acceptance of growth monitoring, not much was known about the diagnostic performance of growth monitoring. This thesis presents referral criteria for length (height), weight and body mass index (BMI) that are able to detect, at an early stage, many children with growth-related conditions at the account of only a limited number of children that do not have a condition. For this purpose, we studied growth of children with Turner’s syndrome, celiac disease, cystic fibrosis, (hypernatraemic) dehydration, obesity and children from the general population. New growth charts are needed to apply the referral criteria. Growth charts for twins were not available, while it is known that the growth pattern of twins differs from that of singletons during infancy. Therefore, we established growth charts for monozygotic and dizygotic twins aged 0-2.5 years. Also, we presented a new reference chart for weight loss of breast-fed infants in the first weeks of life. This chart is needed for the detection of neonates with hypernatraemic dehydration. Furthermore, the thesis presents estimates of the prevalence of childhood overweight and obesity based on BMI. In the Netherlands, the prevalence of childhood overweight and obesity rose between the year 1980 and 1997. Prevalence rose even faster between 1997 and 2003. On average, 14.5% of the boys and 17.5% of the girls were overweight in 2003. More girls than boys were overweight and obese at all ages. A complicating factor in the use of BMI as a measure of overweight in children is the presence of height bias. With BMI, tall children are proportionally more overweight than short children. The odds ratio of overweight in tall boys aged 4-14 years compared to short boys is 4.6. This ratio is 3.8 for tall girls aged 4-12 years of age compared to short girls. This thesis proposes an alternative definition for overweight. In conclusion, this is the first evidence-based investigation of referral criteria in growth monitoring. Valid and efficient referral criteria based on growth are possible. Proper application of these rules in growth monitoring leads to early identification of children with growth-related conditions.