Insulin-dependent diabetes in a Scottish region: incidence and urban/rural differences

Creating a national register of childhood type 1 diabetes using routinely collected hospital data

INTRODUCTION

There is no national register of childhood type 1 diabetes mellitus for England. Our aim was to assess the feasibility of using routine hospital admissions data as a surrogate for a childhood diabetes register across England, and to create a geographically referenced childhood diabetes dataset for use in epidemiologic studies and health service research.

METHODS

Hospital Episodes Statistics data for England from April 1992 to March 2006 referring to a type 1 diabetes diagnosis in 0-14 yr olds were cleaned to approximate an incident dataset. The cleaned data were validated against regional population-based register data, available for Yorkshire and the area of the former Oxford Regional Health Authority.

RESULTS

There were 32 665 unique cases of type 1 and type unknown diabetes over the study period. The hospital-derived data improved in quality over time (91% concordance with regional register data over the period 2000-2006 vs. 52% concordance over the period 1992-1999), and data quality was better for younger (0-9 yr) (86.5% concordance with regional register data) than older cases (10-14 yr). Overall incidence was 24.99 (95% confidence interval 24.71-25.26) per 100 000. Basic trends in age distribution, seasonality of onset, and incidence matched well with previously reported findings.

CONCLUSION

We were able to create a surrogate register of childhood diabetes based on national hospital admissions data, containing approximately 2300 cases/yr, and geo-coded to a high resolution. For younger cases (0-9 yr) and more recent years (from 2000) these data will be a useful resource for epidemiological studies exploring the determinants of childhood diabetes.

Socioeconomic conditions and type 1 diabetes in childhood in North Rhine-Westphalia, Germany

AIMS/HYPOTHESIS

The aim of the study was to investigate the relationships between childhood type 1 diabetes and socioeconomic conditions, which might provide clues to the aetiology of the disease.

MATERIALS AND METHODS

In an ecological study, we investigated the relationships between socioeconomic conditions and the incidence of type 1 diabetes incidence among children aged 0-14 years in North Rhine-Westphalia (NRW), Germany, between 1996 and 2000 at the level of the 33 districts. Incidence data were obtained from the population-based NRW diabetes register and regional socioeconomic data from official statistics. Associations were assessed by Poisson regression models and Bayesian conditionally autoregressive regression models (CAR).

RESULTS

In simple Poisson regression, population density, proportion of non-German nationals in the population, measures of income, education and professional training, and deprivation scores were significantly associated with diabetes risk (p < 0.01). An increase of about one interquartile range (IQR) in population density, proportion of non-German nationals or household income was associated with a 9-12% decrease in diabetes incidence. A rise of about one IQR in income ratio, measures of education and professional training, or in deprivation score (high values correspond to high deprivation) was associated with an 8-12% incidence increase. There was a significantly 'linear' increasing incidence trend across five deprivation classes (relative risk: 1.06; 95% CI: 1.03-1.09). All associations were confirmed when overdispersion and spatial autocorrelation were accounted for in Poisson and CAR models.

CONCLUSIONS/INTERPRETATIONS

The results raise the possibility that the risk for type 1 diabetes is higher for children living in socially deprived and less densely populated areas. Subsequent investigations are necessary to verify the observed ecological relations at the individual level and to identify the causal factors behind the socioeconomic indicators.

Secular trends, disease maps and ecological analyses of the incidence of childhood onset Type 1 diabetes in Northern Ireland, 1989-2003

AIMS

To investigate secular trends in the incidence of Type 1 diabetes in Northern Ireland over the period 1989-2003. To highlight geographical variations in the incidence of Type 1 diabetes by producing disease maps and to compare incidence rates by relevant area characteristics.

METHODS

New cases of Type 1 diabetes in children aged 0-14 years in Northern Ireland were prospectively registered from 1989 to 2003. Standardized incidence rates were calculated and secular trends investigated. Bayesian methodology was used to produce maps of disease incidence using small geographical areas (582 electoral wards). Ecological analyses were conducted using Poisson regression to investigate incidence rates by area characteristics at a finer geographical subdivision (5022 census output areas).

RESULTS

In Northern Ireland during 1989-2003, there were 1433 new cases, giving a directly standardized incidence rate of 24.7 per 100,000 person-years. This incidence rate increased by a mean of 4.2% per annum. Disease maps highlighted higher incidence rates in the predominately rural north-east of the province and lower incidence rates in the urban areas around Belfast in the east and Derry in the north-west of the province. Ecological analysis identified higher incidence in rural areas (P < 0.001), areas with low migration rates (P = 0.002), affluent areas (P < 0.0001), sparsely populated areas (P = 0.0001) and remote areas (P = 0.005). CONCLUSIONS In Northern Ireland the incidence of Type 1 diabetes is increasing. The observed higher incidence in rural, affluent, sparsely populated and remote areas may reflect a reduced or delayed exposure to infections in these areas.

Type 1 diabetes mellitus in childhood: a matched case control study in Lancashire and Cumbria, UK

AIMS

The aim of the study was to identify environmental risk factors for insulin-dependent diabetes mellitus (Type 1 DM) in childhood.

METHODS

A matched case-control study of Type 1 DM conducted in Lancashire and Cumbria, UK, using a structured interview. Cases (n=196, participation rate 83%) were children under 16 years of age diagnosed prior to October 1998 and attending diabetic clinics. Controls (n=381) were healthy children from the community matched by gender and by age (within a few days of birth). The data were analysed by logistic regression using the technique of Breslow and Day for matched case control studies.

RESULTS

The multivariate regression model showed that the following factors were significantly associated with the risk of developing Type 1 DM (odds ratio, 95% confidence intervals): sharing a room with a sibling (0.458, 0.290-0.721), social contact with other children when aged 6-11 months (0.439, 0.256-0.752), consumption of sugary food (0.080, 0.024-0.261), parental insulin dependent diabetes mellitus (10.651, 3.086-36.761), maternal thyroid disease (4.861, 1.681-14.058), consuming more than one pint of milk per day prior to school entry (0.498, 0.310-0.802), maternal smoking during pregnancy (0.373, 0.218-0.636), a father with no academic qualifications (0.504, 0.278-0.913), maternal age at time of birth (0.900, 0.854-0.948), maternal infections in pregnancy (2.453, 1.011-5.948), other maternal illnesses or conditions in pregnancy (2.007, 1.139-3.535), belonging to an Asian family (0.104, 0.028-0.394), and regular contact with pets and other animals (0.552, 0.309-0.987).

CONCLUSION

Many of the results are consistent with the hygiene hypothesis which links improved living standards with decreased exposure to microorganisms and increased risk of immune mediated disease in childhood. These findings challenge the idea that improved hygiene acts exclusively through a Th2 mechanism leading to atopic disease as Type 1 DM is mediated by a Th1 reaction. The association with maternal smoking could be due to recall bias but a causal link cannot be excluded with confidence.

Drinking water composition and childhood-onset Type 1 diabetes mellitus in Devon and Cornwall, England

AIMS

Previous studies have reported inconsistent results on the association between some compositions (e.g. nitrate) in domestic water and the risk of childhood-onset Type 1 diabetes mellitus. This study aimed to examine the relationship between nitrate, zinc and magnesium in drinking water and the risk of childhood-onset Type 1 diabetes mellitus.

METHODS

The study covers the Cornwall and the former Plymouth Health Authority Regions in the far south-west of England. Five hundred and seventeen children, aged 0-15 years, diagnosed with Type 1 diabetes mellitus between 1975 and 1996, were identified for inclusion in the study. Domestic water data (nitrate, Zn, Mg, Cu, Al, Ca, Fe and Mn) between 1993 and 1997 were provided by South-west Water Plc, UK, for each of the 40 Water Supply Zones in which the subjects had been resident at the time of diagnosis. The standardized incidence ratio (SIR) of the disease was calculated for each Water Supply Zone using the UK 1991 census population data. The relationship between the SIR of the disease and the water quality indicators in thirds (three strata of low, medium and high concentrations) was examined by chi2 test for trend and Poisson regression analysis.

RESULTS

The initial analyses by chi2 test for trend on the relation of SIRs and drinking water compositions suggested that copper, magnesium and nitrate might have some protective effects, but Poisson regression analyses showed that only zinc and magnesium were significant factors. The data suggest that the incidence rate of childhood diabetes is significantly lower when the concentrations of zinc and magnesium in the domestic drinking water are in the range 22.27-27.00 microg/l (incidence rate ratio (IRR), 0.76; 95% CI, 0.59-0.97) and greater than 2.61 mg/l (IRR, 0.72; 95% CI, 0.58-0.91), respectively.

CONCLUSIONS

Our findings suggest evidence of a possible association between zinc and magnesium in the domestic drinking water and childhood diabetes in the far south-west of England. However, these possible protective effects of zinc and magnesium in domestic drinking water warrant further confirmation.

Significant urban/rural differences in the incidence of type 1 (insulin-dependent) diabetes mellitus among Bulgarian children (1982-1998)

The systematic registration of the incidence of childhood (0-14 yr) type 1 (insulin-dependent) diabetes mellitus in Bulgaria dates back to 1973, with an invariably present difference in the incidence according to the area of residence. The present study has been undertaken to assess the trends in the incidence of type 1 diabetes among children in eastern Bulgaria (1982-1998) with respect to area of residence at onset. The data were collected prospectively, with an ascertainment of the primary source of 95.8%. The mean annual incidence is 6.99/100,000 (95% CI = 6.45-7.54), varying between 5.09 and 11.54/100,000. The mean annual incidence in towns is higher than in villages: 7.89 vs. 5.26/100,000, p < 0.0001. A linear trend of increase in the incidence with time is revealed applying Poisson regression analysis, with the area of residence as a strong predictor of the risk (p < 0.001). According to the model, the age-adjusted incidence rose by 4.1% annually. The stratified analysis by age group has found a significant linear trend in those aged 5-9 (p < 0.001) and 10-14 yr (p = 0.002) for both sexes. In conclusion, the markedly increasing incidence of type 1 diabetes among children in this study is strongly dependent on area of residence at onset. We suggest that in conjunction with the pronounced seasonality at the onset of diabetes and its connection with population density, this phenomenon should be regarded as a reflection of environmental influence and further explored.

Social disadvantage, family composition, and diabetes mellitus: prevalence and outcome

OBJECTIVE

To investigate the relation between social disadvantage and family composition on diabetes prevalence and diabetes care outcome.

DESIGN

Retrospective audit in the south west of England of 801 children with diabetes mellitus.

MAIN OUTCOME MEASURES

Prevalence of diabetes in relation to the Townsend index. Admissions to hospital with diabetes related problems, glycated haemoglobin, time spent in hospital, outpatient attendance rates.

RESULTS

There was no association between social status and diabetes prevalence. Social deprivation increased the likelihood of admission for hypoglycaemia. Children living with a single parent were more likely to be admitted to hospital with a diabetes related problem and stay in hospital longer. Having either a parent with diabetes or a single parent increased the rates of clinic non-attendance. No association was identified between medium term diabetes control and either social disadvantage or single parent status.

CONCLUSIONS

Social disadvantage has no effect on diabetes prevalence and little on diabetes outcome in childhood. Family structure and parental diabetes have adverse effects on some aspects of diabetes outcome.

Regional variability in the epidemiology of childhood diabetes in Italy

The incidence rates of IDDM in Italy show remarkable variability. Sardinia, a region with the second highest incidence rate in the world, co-exists with other regions with lower rates. We review and compare epidemiologic data on the incidence of childhood-onset IDDM in Italy. papers published from 1980 to 1996 reporting incidence data in Italian areas were found by search of Medline and non-indexed Italian journals. The incidence data found cover only 57% of the Italian population. The analysis of our results shows how difficult it is to make a careful study of epidemiology of IDDM in Italy. The RIDI (the Registry for Insulin-dependent Diabetes mellitus in Italy) project started in 1996 according to international guidelines. The aims is to coordinate local IDDM registries, to promote the start of new registries in uncovered areas, and to standardize registration and data collection.

Epidemiology of childhood IDDM in Northern Ireland 1989-1994: low incidence in areas with highest population density and most household crowding. Northern Ireland Diabetes Study Group

During the period 1989-1994, 462 cases of insulin-dependent diabetes mellitus were registered among children from Northern Ireland aged under 15 years. The estimated completeness of the register was 98.8% (95% confidence interval (CI) 97.7%, 99.9%). A standardised rate of 19.6 (95% CI 17.8, 21.4) per 100 000 person years was obtained, placing Northern Ireland near the top of the range of published incidence in the United Kingdom, with a rate close to that reported for Scotland. In an analysis based on 217 postcode sectors, areas with a high population density and the most material deprivation were observed to have the lowest incidence rates. After inclusion of population density in a Poisson regression analysis, the component of deprivation which was found to be most significant was household crowding. Relative to children living in areas of low population density, there was a reduced risk for children in medium (relative incidence 0.85 (95% confidence limits CI 0.67, 1.09)) and high (0.62 (95% CI 0.48,0.80)) population density areas. Similarly, relative to children living in areas with low levels of household crowding, there was a reduced risk for children in medium (relative incidence 0.73 (95% CI 0.58,0.93)) and high (0.67 (95% CI 0.53, 0.83)) levels of household crowding. Tests for space-time clustering at diagnosis and at birth were negative. A possible explanation for the differences in incidence rate observed in this study is that exposure to infections very early in childhood is a protective factor. Later infections may act as either initiators or promoters of diabetes, but the absence of space-time clustering suggests that no single specific infectious agent is responsible.

The epidemiology of diabetes mellitus in the United Kingdom: the Yorkshire Regional Childhood Diabetes Register

A register of the incidence of Type 1 (insulin-dependent) diabetes mellitus in the Yorkshire region of the United Kingdom has been completed. A total of 1,490 subjects aged between 0 and 16 years were identified from 1978 to 1990, giving an incidence of 13.7 per 100,000 (ages 0-14) or 13.6 per 100,000 (ages 0-16), comparable to other recent studies in the United Kingdom. An age-period-cohort analysis shows evidence for a modest drift effect of 1.75% per year (95% confidence interval 0.28 to 3.25%). There is a marked epidemic pattern with peaks at 4-year intervals. The age-incidence curve is similar to that reported elsewhere, having peaks in early childhood and puberty. Girls have an earlier pubertal peak than boys. There is substantial seasonal variation in incidence confined to those over 5 years of age. Ascertainment is believed to be very complete, and is estimated to be 97.6% (95% confidence interval 97.2% to 98.1%).

Incidence of type 1 (insulin-dependent) diabetes mellitus in Catalonia, Spain. The Catalan Epidemiology Diabetes Study Group

The incidence of Type 1 (insulin-dependent) diabetes mellitus was prospectively evaluated in Catalonia, Spain in patients up to 30 years of age during the period 1987-1990. The population at risk (0-29 years) consisted of 2,690,394 inhabitants (total population of Catalonia 5,978,638). All the cases were independently identified from four sources: endocrinologists, sales of blood glucose monitors and insulin pen injectors, diabetes societies and diabetic summer camps. The degree of ascertainment was 90.1%. The overall observed incidence rate was 10.7 per 100,000 per year, being 11.5 per 100,000 per year in the 0-14 age group. The incidence in males (12.0 per 100,000 per year) was higher than in females (9.3 per 100,000 per year), with a male/female ratio of 1.36/l. The sex differences were only present in cases over 14 years of age. Age specific incidence rates per 100,000 per year were 4.4 (confidence interval 95%: 3.2-5.7) in the age group 0-4, 9.9 (8.5-11.4) in 5-9, 17.5 (15.7-19.4) in 10-14, 11.4 (9.9-13.0) in 15-19, 11.3 (9.7-13.0) in 20-24 and 8.5 (7.2-9.9) in 25-29. There was a seasonal onset pattern, with the highest incidence in winter (December-February). We conclude that the incidence of Type 1 diabetes observed in Catalonia during the period 1987-1990 is higher than that recently reported in other Mediterranean countries. This study offers the first standardized data on Type 1 diabetes incidence in Catalonia, including cases up to 30 years, and contributes to the knowledge of the epidemiology of diabetes in South Europe.

The Dundee prevalence study of insulin-treated diabetes; intervals between diagnosis and start of insulin therapy

A population-based survey of the prevalence of insulin-treated diabetes mellitus in the Dundee area showed a crude prevalence of 0.34%, but analysis by interval between diagnosis of diabetes and start of insulin shows that around a third of patients started insulin therapy more than 1 month after diagnosis. This suggests that the prevalence of insulin-dependent diabetes is around 0.2% of the population, with the other patients being those with non-insulin-dependent diabetes who need insulin for metabolic control, though there is an intermediate zone where classification is difficult. There is a male excess. The proportion of true insulin-dependent diabetes falls with age of onset, but around 50% of such patients have an onset over the age of 30 years.

The cost of diabetes

This paper estimates the cost of diabetes in England and Wales in 1984 to be in excess of 259.5 million pounds. The costing methodology used follows the 'cost of illness' framework. This framework defines three elements for costing: direct, indirect and psychological, although the latter element is left out of the calculation because monetary valuations for this element have never been adequately estimated. Direct costs include resources used to prevent, detect, and treat diabetes. Indirect costs relate to the loss of productive output caused by absenteeism, early retirement, and premature mortality. The estimate which has been obtained is likely to be an underestimate because of the weaknesses and gaps in the data sets. The estimate of the total lost earnings from diabetes varied greatly according to the choice of absentee rate. If there was no significant difference between absenteeism in the diabetic community and the non-diabetic community then the cost of diabetes would be 259.5 million pounds. If on the other hand the diabetic community was prone to three times as much absenteeism as the non-diabetic community then the cost of diabetes would rise to 602.5 million pounds. The costs of diabetes as a subsidiary diagnosis are extremely difficult to identify. They have been estimated in this study to be 86 million pounds but this is thought to be an overestimate. Nevertheless the cost of diabetes is significant and thus the search for more efficient treatment regimens may reduce such costs as well as enhance the quality of life of the patients concerned.(ABSTRACT TRUNCATED AT 250 WORDS)

The incidence of type 1 (insulin-dependent) diabetes mellitus in subjects aged 0-19 years in Luxembourg: a retrospective study from 1977 to 1986

A decrease in the incidence of Type 1 (insulin-dependent) diabetes mellitus in the age group 0-14 years has been observed from north to south over north-western Europe. To evaluate whether this trend could be found in Luxembourg (a small country between the Netherlands and France) we performed a retrospective study over a period of 10 years. Information concerning all Type 1 diabetic patients (aged 0-19 years at diagnosis), diagnosed between January 1, 1977 and December 31, 1986 was obtained through paediatricians, internists, general practitioners and the Luxembourg Diabetes Association (LDA). The LDA was used as the ascertainment group (to estimate the real number and incidence of Type 1 diabetes mellitus). During the study period 91 Type 1 diabetic patients aged between 0-19 years were diagnosed. An incidence of 11.2 was found in boys (0-19 years). Girls in the same age group showed a considerably lower incidence of 8.8. Standardised incidence (using as standard the world population) revealed an almost similar incidence in the Netherlands and Luxembourg (respectively 10.3 and 10.2) for the age group aged 0-14 years. In France a considerably lower incidence is found (3.6). To what extent different methodology contributes to the differences remains to be clarified. Further prospective studies are necessary to investigate the role of environmental and genetic factors.

The incidence of childhood diabetes in certain parts of Scotland

The incidence of diabetes in children under 12 years of age has been studied in three regions of Scotland from 1976 to 1986. These areas represent more than half of the Scottish population of that age group. The overall annual incidence is 17.6 per 100,000, ranging from 16.8 in densely populated areas to 23.4 in more rural areas. Earlier studies have concerned the age group 0-18 years so the present results from a younger age group are, as expected, slightly lower but show the same trends. After a rise to 1983 there appears to have been a drop, but not in all areas. The danger of drawing conclusions from areas of low population or from short periods of time is stressed.

Geographical variation in the incidence of diabetes mellitus in Scottish children during the period 1977-1983

Routinely collected Scottish hospital discharge data were used to identify newly diagnosed cases of diabetes mellitus under the age of 19 years. In the period 1977-83 there were 2183 cases, an average annual incidence of 21.0 per 100,000 per annum. This rate is one of the highest reported and represents a continuation of the increase in incidence which occurred during the period 1968-76. Statistically significant geographical variation in incidence was observed with the higher incidence in the least densely populated areas. Seasonal variation in the month of first admission was evident in all except the under-five age group with peaks occurring in winter. An estimated 60% of newly diagnosed cases were readmitted within 5 years and the pattern of readmission was found to differ little between males and females or between age groups.

Type 1 (insulin-dependent) diabetes in Tasmania: prevalence and apparent regional differences

The results of a cross-sectional study of Type 1 (insulin-dependent) diabetes in the total population of Tasmania are described. Tasmanians, predominantly of British origin, live in a temperate island situated to the south-east of mainland Australia. For males and females respectively, prevalence in 1984 was 1.1 +/- 0.1 and 0.9 +/- 0.1 per 1,000 at all ages, 0.6 +/- 0.2 and 0.5 +/- 0.2 per 1,000 in subjects aged 0-14 years, rising to 1.2 +/- 0.2 and 1.1 +/- 0.2 per 1,000 in those aged 0-29 years. Prevalence in the 0-19 year age range was 0.8 +/- 0.2 per 1,000 in both sexes. Prevalence fell in both sexes from the third decade of life. A statistically significant excess in prevalence was found in the urban, as compared with the rural, sector of the community. The urban relative risk was greatest in subjects aged 10-19 years. According to reported month of onset (commencement of insulin treatment) there was a suggestion of seasonal trend in the rural, but not in the urban subjects. Longitudinal studies of Type 1 diabetes in Tasmania are now required if these findings are to be confirmed, and their possible aetiological implications explored.

The Oxford Community Diabetes Study: evidence for an increase in the prevalence of known diabetes in Great Britain

A prevalence survey for known diabetes was conducted in a geographically defined population of nearly 40,100 in Oxford in April 1982. The age-adjusted prevalence rate was 10.4/1000 which did not differ significantly from age-adjusted rates of 9.5/1000 in Poole and 10.5/1000 in Southall. The prevalence increased with age and was higher in men than women over the age of 30 years. Our results confirm that there has been a change in the male to female sex ratio and suggest that there are about 500,000 diagnosed diabetics in England and Wales including about 190,000 insulin-treated patients. These findings are consistent with a secular increase in the prevalence of diagnosed diabetes over the last two decades which has important implications for the planning and provision of resources for care.