Early social mixing and childhood Type 1 diabetes mellitus: a case-control study in Yorkshire, UK.

AIMS: Evidence from animal models shows an increased risk of Type 1 diabetes mellitus associated with the absence of early life exposure to pathogens. To test this 'hygiene hypothesis', patterns of social mixing and infections in the first year of life and the risk of developing autoimmune diabetes in childhood were examined. METHODS: Personal interviews were conducted with the mothers of 220 children with Type 1 diabetes (0-15 years) and 433 age/sex matched controls from a population-based case control study in Yorkshire, UK. Social mixing including attendance at daycare, and infections occurring under 1 year of age were measures of exposure. Adjusted odds ratios (OR) were derived using conditional logistic regression. RESULTS: Frequency of attendance at daycare during the 1st year of life was inversely associated with childhood diabetes (OR 0.71, 95% confidence interval 0.51-1.00, P = 0.05), a finding not explained by mother's age, level of education or maternal diabetes. Increasing numbers of children in the daycare setting and numbers of sessions attended were significantly associated with increasing protection from diabetes. The strongest effect was observed in children with diabetes diagnosed aged 0-4 years. CONCLUSIONS: Social mixing through attendance at daycare in early infancy appears to confer protection against the development of childhood diabetes. This may be mediated through exposure to infectious agent(s) as a significant dose-response effect was evident with increasing numbers of child 'contacts'. These findings suggest early infectious exposure may play a role in the development of immunoregulatory mechanisms which protect against diabetes and further work is warranted.

Perinatal and neonatal determinants of childhood type 1 diabetes. A case-control study in Yorkshire, U.K.

OBJECTIVE: To identify environmental factors that exert their effect in the perinatal and neonatal period and influence the subsequent onset of insulin dependent (type 1) diabetes during childhood. RESEARCH DESIGN AND METHODS: A population-based case-control study of data abstracted from the hospital obstetric and neonatal records of 196 children with type 1 diabetes and 325 age- and sex-matched control subjects. Analysis of matched sets by conditional logistic regression was conducted for a range of perinatal and neonatal factors. RESULTS: A significantly raised risk was observed for illnesses in the neonatal period (OR 1.61, 95% CI 1.06-2.44), the majority of which were infections and respiratory difficulties. Exclusive breast feeding as the initial feeding method was significantly protective (OR 0.65, 95% CI 0.45-0.94). There were no significant associations with high- or low-birth weight, being firstborn or small-for-dates. All factors significant (5% level) for the entire dataset, that is, maternal age, type 1 diabetes in mothers, preeclampsia, delivery by cesarean section, neonatal illnesses, and initial breast feeding were modeled and the OR remained significant for all variables other than cesarean section. CONCLUSIONS: The findings are based on medical record data that cannot be subject to biased recall of mothers. Neonatal illnesses increased and initial breast feeding decreased the risk of childhood type 1 diabetes. Further determinants of risk are mothers with type 1 diabetes, older mothers, and preeclampsia during pregnancy.

Descriptive epidemiology of gastrointestinal non-Hodgkin's lymphoma in a population-based registry.

The incidence of non-Hodgkin's lymphoma (NHL), particularly at certain extranodal sites, has been demonstrated to be rising, at least in the USA, more than for any other malignancy. One of the major sites of extranodal NHL is the gastrointestinal tract, though little is known of its epidemiological characteristics. Over an 8-year period (1986 to 1993) 1069 primary gastrointestinal NHL cases were reported to the Leukaemia Research Fund Data Collection Survey which covers many parts of England and Wales. Age-standardized incidence rates of gastrointestinal NHL at all sites (0.58/10(5) per year), gastric (0.24/10(5) per year), small bowel (0.17/10(5) per year) and large bowel (0.06/1(5) per year) confirmed that the UK has the lowest rates of gastrointestinal NHL in Europe. An excess of males was observed at all ages and for all sites. Time-trend analyses showed annual increases in incidence rates for gastric (6.3%) and small bowel (5.9%) NHL although a concomitant decrease in gastrointestinal NHL of unknown site suggested that at least part of these increases had resulted from more accurate diagnoses. Overall, the incidence of gastrointestinal NHL significantly increased by 2.7% per annum and was limited to the population aged over 50 years in this series.