Paediatric coeliac disease in Scotland: epidemiological trends, management and adolescent adherence to gluten-free diet

The incidence of paediatric coeliac disease (CD) is rising globally. It is uncertain whether this is attributed to improved case ascertainment or signifies a true rise in numbers. Geographical variation in incidence has also been reported in some European countries, although it is not known whether regional differences present in Scotland. Furthermore, data on the management of children diagnosed with CD in Scotland is lacking. The cornerstone of CD treatment is a strict gluten-free diet (GFD). Adherence may reduce risk of future complications including osteoporosis, malignancy and fertility difficulties. Nonetheless, the GFD is known to be particularly challenging during adolescence and may be nutritionally inadequate. Limited adolescent research addresses factors associated with adherence to the GFD, the diet’s nutritional quality or effect on health-related quality of life (HRQoL). Retrospective longitudinal and prospective regional trends in age-sex standardised incidence of childhood CD (≤16 years) in Scotland were determined. Data on case presentation, reasons for diagnosis and the management of newly diagnosed children were collected. A cross-sectional study was undertaken to identify adherence to the GFD in Scottish adolescents with CD (11-18 years) using a short validated questionnaire. A further questionnaire was developed to identify factors associated with adherence to the GFD. Teenagers’ energy and nutrient intakes were compared to Dietary Reference Values (DRVs) and a healthy, age-matched control group. Generic and disease-specific HRQoL indices were compared between adherent teenagers, non-adherent teenagers and age-matched controls. The incidence of paediatric CD in Scotland between 01.09. 09 and 31.08.10 was 10.0/100,000/yr. Incidence in the East was 16.3, West 8.1 and North 7.7. More than twice the incidence of cases were diagnosed due to active screening in the East (4.6) compared to the West (2.0) and North (1.3), as was the incidence of classical cases. Significantly more CD diagnostic antibody tests were performed per head of population in the East compared to the West (OR 1.65, 95% CI 1.57-1.73) and North (OR 1.81 95% CI 1.70-1.92). The incidence of childhood CD rose from 1.8 (95% CI 1.1-2.7) to 11.7 (95% CI 9.8-13.9) per 100,000 from 1990-1994 to 2005-2009, respectively (p<0.0001). The incidence of non-classical and actively screened cases increased 1467% (p<0.05) and 1100% (p<0.001) from 1990-1999 to 2000-2009, respectively. A significant rise in the incidence of Oslo classical cases from 1.51 (95% CI 0.91-2.38) in 1990-1994 to 5.22 (95% CI 3.98-6.75) in 2005-2009 (p<0.01) remained. A number of differences in the dietetic management of newly diagnosed children were observed between a regional (multidisciplinary team) and a district general (dietetic-led) clinic. Differences in the management of dietary concerns as well as the type of education and resources provided were reported. Sixteen participants were categorised as non-adherent to the GFD in the adolescent study (41%; 0/7 boys, 16/32 girls). Male gender, being a member of a CD support group, ability to follow a GFD on holiday, when traveling and at social and special events were associated with better adherence to the GFD (p<0.05). Never checking food labels was associated with poorer adherence. Compared to controls, boys and girls with CD had higher median energy intakes (p<0.05). Mean percentage energy intake from protein, saturated fat and non-milk extrinsic sugar was significantly higher in the CD group compared to controls and DRVs (p<0.05). Ten (34%) girls with CD II had estimated iron intakes below the Lower Reference Nutrient Intake (LRNI). This was not significantly different compared to NDNS data (44% 0.05). Adherent adolescents had significantly better generic HRQoL scores for the domains ‘physical health’ and ‘self perception’ compared to non-adherent teenagers and controls (p<0.05). Evidence of more actively screened cases and more antibody tests performed in the East suggests the higher incidence observed may be due to a lower threshold to test. An environmental influence cannot be dismissed since more classic cases were also captured. The incidence of pediatric CD increased 6.4-fold over the 20 years studied. This rise is significant for classic CD, indicating a true rise in incidence. Further research is needed to highlight the role of exogenous factors in CD development and whether differences in management affect disease outcomes. A number of factors appear to be associated with adherence to the GFD in Scottish adolescents and dietary intakes were of concern regarding the distribution from different macronutrients. The results imply that HRQoL should be monitored alongside adherence in this population. Further studies are required to identify independent predictors of adherence, the nutritional status of teenagers following a GFD and to ascertain whether poor HRQoL is a cause or effect of non-adherence.