Caesarean section is associated with an increased risk of childhood-onset type 1 diabetes mellitus: a meta-analysis of observational studies

AIMS/HYPOTHESIS

The aim of this study was to investigate the evidence of an increased risk of childhood-onset type 1 diabetes in children born by Caesarean section by systematically reviewing the published literature and performing a meta-analysis with adjustment for recognised confounders.

METHODS

After MEDLINE, Web of Science and EMBASE searches, crude ORs and 95% CIs for type 1 diabetes in children born by Caesarean section were calculated from the data reported in each study. Authors were contacted to facilitate adjustments for potential confounders, either by supplying raw data or calculating adjusted estimates. Meta-analysis techniques were then used to derive combined ORs and to investigate heterogeneity between studies.

RESULTS

Twenty studies were identified. Overall, there was a significant increase in the risk of type 1 diabetes in children born by Caesarean section (OR 1.23, 95% CI 1.15-1.32, p < 0.001). There was little evidence of heterogeneity between studies (p = 0.54). Seventeen authors provided raw data or adjusted estimates to facilitate adjustments for potential confounders. In these studies, there was evidence of an increase in diabetes risk with greater birthweight, shorter gestation and greater maternal age. The increased risk of type 1 diabetes after Caesarean section was little altered after adjustment for gestational age, birth weight, maternal age, birth order, breast-feeding and maternal diabetes (adjusted OR 1.19, 95% CI 1.04-1.36, p = 0.01).

CONCLUSIONS/INTERPRETATION

This analysis demonstrates a 20% increase in the risk of childhood-onset type 1 diabetes after Caesarean section delivery that cannot be explained by known confounders.

Major childhood infectious diseases and other determinants associated with type 1 diabetes: a case-control study

The objective of the study was to evaluate the association between infectious diseases and other events pertaining to childhood medical history and type 1 diabetes. A case-control study was carried out, taking as cases 159 type 1 diabetic patients (0-29 years) recorded from 1988 to 2000 within the population registry of the Pavia province (North Italy). As controls 318 non-diabetic subjects were matched by age and sex. A questionnaire was administered by standardised interviewers. Data were analysed by conditional logistic regression. Viral childhood diseases (OR 4.29; 95%CI 1.57-11.74) and bottle feeding (OR 1.83; 95%CI 1.08-3.09) were directly correlated to type 1 diabetes; an inverse correlation was found for vitamin D administration during lactation (0-14 years) (OR 0.31; 95%CI 0.11-0.86) and for history of scarlet fever in both sexes and age groups (OR 0.19; 95%CI 0.08-0.46). Most associations of the studied variables confirm already known findings. The significant inverse correlation of type 1 diabetes with scarlet fever history is a peculiar finding, the meaning of which is still obscure, although it has been recently described that streptococcal A infections are regulated by HLA class II alleles.

Role of socioeconomic indicators in the prediction of all causes and coronary heart disease mortality in over 12,000 men--The Italian RIFLE pooling project

The relationship of socioeconomic indicators (education, occupation and residence) to short-term all cause mortality and coronary heart disease (CHD) mortality was evaluated in an Italian population sample. Socioeconomic indicators (education, occupational level and residence) and major CHD risk factors were measured in 12,361 males aged 40-69 years; mortality data by cause were collected for the next 6 years. All cause and CHD mortality risk ratio (RR) in the different educational and occupational levels and residence were computed by Cox proportional hazards models. After 6 years 385 men died, of whom 105 were coronary fatalities. No association with educational level was found for all cause mortality (RR: 1.00 high, 0.71 medium, 0.77 low) and for CHD mortality (RR: 1.00 high, 0.39 intermediate, 0.71 low). Occupational level was significantly associated (p < 0.031) with all cause mortality (RR: 1.00 high-intermediate, 1.27 low). Urban vs. rural residence (RR: 1.00) showed a RR for all cause mortality of 1.33 (p < 0.011). Adjustment for bio-behavioral risk factors did not change the above results; only mortality for CHD of urban vs. rural residents increased (RR: 1.94, p = 0.004). In conclusion the negative association of mortality with occupational level, albeit not with education, indicates that occupation is a better indicator of socioeconomic status in Italy. Status incongruity as well as residence in an urban environment could be risk conditions for total and CHD mortality.

[Socioeconomic indicators and mortality for ischemic cardiopathy in the RIFLE population. The RIFLE Group. Risk Factors and Life Expectancy]

The aim of this paper was to evaluate the relationship between socioeconomic indicators (education, occupation and residence) and short-term CHD mortality in an Italian population sample. Socioeconomic indicators and major CHD risk factors (BMI, SBP, DBP, TOT-CH, HDL-CH and TRIG) were measured in 15,315 males aged 40-69 years; mortality data by cause were collected for the next six years. CHD mortality risk ratio (RR) in the different educational and occupational levels and by residence was computed by Cox proportional hazards models. The association between socioeconomic indicators and CHD risk factors was explored by covariance and logistic regression analysis. After six years, 632 men died, 181 of whom because of coronary fatalities. No association with educational level was found for CHD mortality (RR = 1.00 high, 0.69 intermediate, 0.92 low), nor did occupational level show a significant association. Urban vs rural residence (RR = 1.00) showed a RR for CHD mortality of 1.35. Adjustment for bio-behavioral risk factors did not change the above results; only mortality for CHD of urban vs rural residents increased (RR = 1.63, p < 0.003). By considering the interaction between schooling and occupation, it was found that education appropriated to occupational level was a protective factor. The study does not indicate any association between education/occupational level and CHD mortality in male RIFLE population samples. The mean level of major CHD risk factors within different educational/occupational levels supports these results. Status incongruity as well as residence in an urban environment proved to be risk conditions for CHD mortality.

IDDM in the province of Pavia, Italy, from a population-based registry.A descriptive study

OBJECTIVE

To report the incidence of insulin-dependent diabetes mellitus (IDDM) in the Province of Pavia, Italy, in the 0- to 29-year-old age-group between 1988 and 1992. Urban versus rural residence, socioeconomic level, and family size of IDDM cases were also investigated.

RESEARCH DESIGN AND METHODS

A prospective register was established in 1988 to collect all newly diagnosed IDDM patients with onset before 30 years of age. The primary data source was based on notification of new cases by hospitals, out-patient clinics, family doctors, and pediatricians. The secondary and independent data source consisted of the registries of prescriptions for insulin syringes in the health districts of the province.

RESULTS

In 5 years (1988-1992), 66 cases of IDDM in the 0- to 29-year-old age-group were identified. The completeness of ascertainment was 100% for the combined sources. Age-adjusted (world-standardized) incidence rates per 100,000 (95% confidence interval) were 9.52 (6.42-13.61), 6.72 (4.68-9.34), and 8.27 (6.42-10.58), respectively, for the age-groups 0-14, 15-29, and 0-29. The rates were higher for residents in urban areas. The number of children in the families of IDDM patients was significantly higher than in the reference population.

CONCLUSIONS

Our data indicate the concordance of IDDM incidence rates with the North-Italian rates and a possible association of the disease with environmental factors. These factors might enhance the susceptibility to IDDM in genetically predisposed individuals.

Percutaneous embolization of subclavian pseudoaneurysmatic arteriovenous iatrogenic fistula by steel coils

A case of iatrogenic subclavian arterio-venous fistula with pseudoaneurysm formation is described. Treatment by means of percutaneous embolization, on the venous side, with steel coils has been successful; in order to avoid complications, the arterial side was blocked by an angioplasty balloon. After discussing the more common complications of subclavian vein puncture, the Authors conclude that percutaneous embolization is a valuable alternative to surgery even in such a lesion, especially when the surgical risk is high.

The relationship between education and risk factors for coronary heart disease. Epidemiological analysis from the nine communities study. The Research Group ATS-OB43 of CNR

In nine samples of adult populations (2707 males and 2871 females, aged 20-59 years) we studied the relationship between educational level and several lifestyle factors at risk for coronary heart disease (CHD), (i.e., smoking, alcohol consumption, dietary fat intake, sedentary behaviour at work and leisure) and the association between education and certain CHD risk factors (i.e., total cholesterol, HDL-cholesterol, triglycerides, systolic and diastolic blood pressure, body mass index). The data were analyzed separately in samples from North, Central and Southern Italy. The results show that educational level is often associated to the lifestyle factors considered here. This association was positive for both men and women for physical activity at leisure and work stress and only for women with respect to smoking. It was negative for both men and women for alcohol consumption and physical activity at work and for men only for cigarette smoking. The age-adjusted mean levels of the CHD risk factors show some significant differences among subjects with different educational levels, which were not always the same for the three geographical areas. This was with the exception of BMI in females, which appears negatively associated to education in all areas. These differences decreased after adjustments were made for daily cigarette smoking, wine consumption and dietary fat intake. Education seems to play a determining role in lifestyle, however, its direct and indirect effects on some major CHD risk factors are somewhat different in areas at different socio-economic conditions.