Context and disease when disease risk is low: the case of type 1 diabetes in Sweden

Incidence of type 1 diabetes by socio-demographic characteristics among South Australian children: Whole-of-population study

AIM

To describe and compare the incidence of type 1 diabetes (T1D) in South Australia by individual and area-level socio-economic characteristics among children aged ≤11 years.

METHODS

This is a whole-of-population, data linkage study (n = 231 685) conducted in South Australia, and included children born from 2002 to 2013, hospitalisation followed from 2002 to 2014. The study used de-identified, linked administrative hospitalisation, birth and perinatal data from the South Australian Early Childhood Data Project. Incidence was calculated by identifying T1D cases from T1D-related hospitalisations using International Classification of Disease, 10th Revision, Australian Modification diagnosis codes (E10, E101-E109).

RESULTS

Overall, 333 children aged ≤11 years (173 boys) were identified as having T1D. The T1D incidence rate was 23.0 per 100 000 person-years (95% confidence interval (CI): 20.7-25.7), with no sex difference. T1D incidence was higher among children whose mothers were Caucasian, private patients and whose parents were employed. For example, T1D incidence was 26.0 per 100 000 (95% CI: 22.8-29.5) among children with both parents employed, compared to 20.0 per 100 000 (95% CI: 12.3-30.6) among children with both parents unemployed. There was no clear gradient in the association between area-level socio-economic position and T1D, with highest incidence for the fourth quintile (26.5 per 100 000 (95% CI: 20.9-33.1)). The most advantaged area (19.4 per 100 000 (95% CI: 13.8-26.5)) had lower incidence than the most disadvantaged area (23.5 per 100 000 (95% CI: 18.9-28.9)).

CONCLUSION

T1D incidence rates differed depending on the measures of socio-economic characteristics. Individual-level indicators showed higher incidence among more advantaged children; however, there was no clear area-level socio-economic patterning of T1D.

Short Term Survival after Admission for Heart Failure in Sweden: Applying Multilevel Analyses of Discriminatory Accuracy to Evaluate Institutional Performance

BACKGROUND

Hospital performance is frequently evaluated by analyzing differences between hospital averages in some quality indicators. The results are often expressed as quality charts of hospital variance (e.g., league tables, funnel plots). However, those analyses seldom consider patients heterogeneity around averages, which is of fundamental relevance for a correct evaluation. Therefore, we apply an innovative methodology based on measures of components of variance and discriminatory accuracy to analyze 30-day mortality after hospital discharge with a diagnosis of Heart Failure (HF) in Sweden.

METHODS

We analyzed 36,943 patients aged 45-80 treated in 565 wards at 71 hospitals during 2007-2009. We applied single and multilevel logistic regression analyses to calculate the odds ratios and the area under the receiver-operating characteristic (AUC). We evaluated general hospital and ward effects by quantifying the intra-class correlation coefficient (ICC) and the increment in the AUC obtained by adding random effects in a multilevel regression analysis (MLRA). Finally, the Odds Ratios (ORs) for specific ward and hospital characteristics were interpreted jointly with the proportional change in variance (PCV) and the proportion of ORs in the opposite direction (POOR).

FINDINGS

Overall, the average 30-day mortality was 9%. Using only patient information on age and previous hospitalizations for different diseases we obtained an AUC = 0.727. This value was almost unchanged when adding sex, country of birth as well as hospitals and wards levels. Average mortality was higher in small wards and municipal hospitals but the POOR values were 15% and 16% respectively.

CONCLUSIONS

Swedish wards and hospitals in general performed homogeneously well, resulting in a low 30-day mortality rate after HF. In our study, knowledge on a patient's previous hospitalizations was the best predictor of 30-day mortality, and this information did not improve by knowing the sex and country of birth of the patient or where the patient was treated.

[Relevance of the health insurance databases to study spatial disparities in asthma prevalence: A study in southeastern France]

BACKGROUND

Data on asthma prevalence at a small-area level would be useful to set up and monitor French local public health policies. This study, based on drug reimbursement databases in southeastern France, aimed to (1) compare asthma-like disorders prevalence estimated by using three different indicators; (2) study sociodemographic characteristics associated with these indicators; (3) verify whether these indicators are equivalent to study geographical disparities of the asthma-like disorders prevalence at a small-area level.

METHODS

The study was conducted among the beneficiaries of the National Health Insurance Fund aged 18-44 years residing in southeastern France in 2010 (n=1,371,816). Using data on asthma drugs reimbursements (therapeutic class R03), we built three indicators to assess asthma-like disorders prevalence: at least 1, 2 or 3 purchase(s) in 2010. We analyzed sociodemographic characteristics associated with these indicators, and their geographical disparities at a small-area level using multilevel logistic regression models.

RESULTS

The crude asthma-like disorders prevalence varied between 2.6 % and 8.4 % depending on the indicator. It increased with age, was higher for women than for men, and among low-income people for all three indicators. We measured significant geographical disparities. Areas with high prevalence rates were the same regardless of the indicator.

CONCLUSION

The indicators built in this study can be useful to identify high prevalence areas. They could contribute to launch discussion on environmental health issues at the local level.

The trends and the risk of type 1 diabetes over the past 40 years: an analysis by birth cohorts and by parental migration background in Sweden

OBJECTIVE

To investigate the trends and the risk of developing type 1 diabetes in the offspring of Swedes and immigrants by specific parental migration background, age, sex and birth cohort.

DESIGN

Registry-based cohort study.

SETTING

Using Swedish nationwide data we analysed the risk of developing type 1 diabetes in 3 457 486 female and 3 641 304 male offspring between 0 and 30 years of age, born to native Swedes or immigrants and born and living in Sweden between 1969 and 2009. We estimated incidence rate ratios (IRRs) with 95% CIs using Poisson regression models. We further calculated age-standardised rates (ASRs) of type 1 diabetes, using the world population as standard.

RESULTS

We observed a trend of increasing ASRs among offspring below 15 years of age born to native Swedes and a less evident increase among offspring of immigrants. We further observed a shift towards a younger age at diagnosis in younger birth cohorts in both groups of offspring.Compared with offspring of Swedes, children (0-14 years) and young adults (15-30 years) with one parent born abroad had an overall 30% and 15-20% lower IRR, respectively, after multivariable adjustment. The reduction in IRR was even greater among offspring of immigrants if both parents were born abroad. Analysis by specific parental region of birth revealed a 45-60% higher IRR among male and female offspring aged 0-30 years of Eastern Africa.

CONCLUSIONS

Parental country of birth and early exposures to environmental factors play an important role in the aetiology of type 1 diabetes.

Type I diabetes among children and young adults: the role of country of birth, socioeconomic position and sex

OBJECTIVE

To investigate associations between country of birth, parental country of birth, and education with respect to incidence rate and time trends of type 1 diabetes mellitus (T1DM) among children and young adults.

METHODS

We followed a nation-wide cohort of 4 469 671 males and 4 231 680 females aged 0-30 years between 1969 and 2008. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) for T1DM were calculated using Poisson regression models. We further calculated age-standardized rates (ASRs) of T1DM, using the world population as standard.

RESULTS

During the study period, the ASR of T1DM increased among children younger than 15 years, but not among young adults (15-30 years). Compared with Swedish-born children, male and female immigrant children had 44 and 42% lower IRR of TIDM, respectively. Among offspring to immigrants, corresponding decreases in IRRs were 27 and 24%, respectively. Compared with children to parents with high education, male children to parents with low education had a 10% decreased IRR of T1DM, while no effect was observed among females. The IRR of T1DM increased with increasing age and calendar time of follow-up in both sexes (p-for trend <0.0001). In young adults, the IRR among immigrants decreased by 32% in males and 22% in females, while corresponding reductions in IRRs were less in offspring to immigrants.

CONCLUSIONS

We found a lower IRR of T1DM among offspring to immigrants, but especially among young immigrants compared with Sweden-born individuals. The findings show that environmental factors are important in the etiology of T1DM.

Coeliac disease in children: a social epidemiological study in Sweden

AIM

Little is known on the possible existence of socioeconomic and geographical differences in early coeliac disease (CD) risk. Therefore, we investigated these aspects in children before age two.

METHODS

Linking the Swedish Medical Birth Registry to several other national registries, we identified all singletons born in Sweden from 1987 to 1993 (n = 792,401) and followed them until 2 years of age to identify cases of CD. Applying multilevel logistic regression analysis, we investigated the association between socioeconomic position (SEP) and CD in children and also whether a possible geographical variation in CD risk was explained by individual characteristics.

RESULTS

Low SEP was associated with CD in boys OR 1.37 (95% CI 1.03-1.82), but not in girls OR 0.87 (95% CI 0.68-1.12). We found a considerable geographical variation in disease risk (i.e. intra-municipality correlation ≈ 10%) that was not explained by individual characteristics.

CONCLUSIONS

Low SEP is associated with CD in boys but not in girls. Also, CD appears to be conditioned by geographical area of residence. While our study represents an innovative contribution to the epidemiology of CD in children, the reasons for the observed geographical and socioeconomic differences could be speculated but are still unknown.

Neighborhood level risk factors for type 1 diabetes in youth: the SEARCH case-control study

BACKGROUND

European ecologic studies suggest higher socioeconomic status is associated with higher incidence of type 1 diabetes. Using data from a case-control study of diabetes among racially/ethnically diverse youth in the United States (U.S.), we aimed to evaluate the independent impact of neighborhood characteristics on type 1 diabetes risk. Data were available for 507 youth with type 1 diabetes and 208 healthy controls aged 10-22 years recruited in South Carolina and Colorado in 2003-2006. Home addresses were used to identify Census tracts of residence. Neighborhood-level variables were obtained from 2000 U.S. Census. Multivariate generalized linear mixed models were applied.

RESULTS

Controlling for individual risk factors (age, gender, race/ethnicity, infant feeding, birth weight, maternal age, number of household residents, parental education, income, state), higher neighborhood household income (p = 0.005), proportion of population in managerial jobs (p = 0.02), with at least high school education (p = 0.005), working outside the county (p = 0.04) and vehicle ownership (p = 0.03) were each independently associated with increased odds of type 1 diabetes. Conversely, higher percent minority population (p = 0.0003), income from social security (p = 0.002), proportion of crowded households (0.0497) and poverty (p = 0.008) were associated with a decreased odds.

CONCLUSIONS

Our study suggests that neighborhood characteristics related to greater affluence, occupation, and education are associated with higher type 1 diabetes risk. Further research is needed to understand mechanisms underlying the influence of neighborhood context.

Prevalence of treated diabetes: Geographical variations at the small-area level and their association with area-level characteristics. A multilevel analysis in Southeastern France

AIM

This study estimated geographical variations in the prevalence of treated diabetes (TD) at the small-area level in Southeastern France to determine whether or not the characteristics of these areas (in particular, socioeconomic status or "SES") are associated with TD independent of person-level factors.

METHODS

The study used drug reimbursement data for 2008 from the General Health Insurance Scheme in Southeastern France for beneficiaries aged 18 years or over. TD patients were defined as those to whom oral antidiabetic drugs or insulin had been dispensed at least three times within the year. Area (canton) characteristics associated with the prevalence of TD were studied using multilevel Poisson regression.

RESULTS

In 2008, the crude prevalence of TD in adults in Southeastern France was 5.14%. In addition, TD prevalence was significantly higher in the more deprived and population-dense cantons independent of person-level factors (age, gender, low SES).

CONCLUSION

This study found a positive association between area deprivation and TD, and adds further evidence to the scanty data so far available on this topic. This finding should contribute to pinpointing priority action areas for programmes of diabetes prevention. However, more research is needed to further elucidate the mechanism(s) linking area deprivation and diabetes.