In order to test hypotheses on diet and the risk of cancer, a prospective cohort study was established. A total of 57,055 persons living in Copenhagen and Aarhus, between 50 and 65 years of age, visited a study clinic between December 1993 and May 1997. The participants provided questionnaire data on diet and lifestyle. Furthermore, anthropometric measurements, blood pressure and biological material were collected. All participants will be followed by linkage to health registries including the Cancer Registry and by self-administered follow-up questionnaires. The purpose of this publication is to describe the data-base, which will be available for research in the years to come including the results of the first two years of follow-up.
The aim of this study was to investigate whether air pollution from traffic at a residence is associated with mortality related to type 1 or type 2 diabetes.
We followed up 52,061 participants in the Danish Diet, Cancer and Health cohort for diabetes-related mortality in the nationwide Register of Causes of Death, from baseline in 1993-1997 up to the end of 2009, and traced their residential addresses since 1971 in the Central Population Registry. We used dispersion-modelled concentration of nitrogen dioxide (NO2) since 1971 and amount of traffic at the baseline residence as indicators of traffic-related air pollution and used Cox regression models to estimate mortality-rate ratios (MRRs) with adjustment for potential confounders.
Mean levels of NO2 at the residence since 1971 were significantly associated with mortality from diabetes. Exposure above 19.4 µg/m³ (upper quartile) was associated with a MRR of 2.15 (95% CI 1.21, 3.83) when compared with below 13.6 µg/m³ (lower quartile), corresponding to an MRR of 1.31 (95% CI 0.98, 1.76) per 10 µg/m³ NO2 after adjustment for potential confounders.
This study suggests that traffic-related air pollution is associated with mortality from diabetes. If confirmed, reduction in population exposure to traffic-related air pollution could be an additional strategy against the global public health burden of diabetes.
The objective was to validate the diagnoses of peripheral arterial disease (PAD) in the legs, obtained from national registers in Denmark.
In total, 1435 registered cases of PAD were identified in the Danish National Patient Registry among 57,053 middle aged participants from the Danish Diet, Cancer and Health cohort study. Validation was performed by reviewing all medical records using pre-specified criteria for a diagnosis of PAD.
The overall positive predictive value (PPV) of PAD diagnoses was 69.4% [95% confidence interval (CI) 67.0-71.7]. The PPV of diagnoses given in departments of vascular surgery was significantly higher than diagnoses given in other departments: 71.9% (95% CI 69.2-74.4) versus 58.3% (95% CI 52.2-64.2), respectively. In a sub-study, 141 potential cases of PAD also registered in the Danish National Vascular Registry were evaluated, and a PPV of 87.9% (95% CI 81.4-92.4) was found for these diagnoses.
More than 30% of the diagnoses of PAD notified in the Danish National Patient Registry were not valid, stressing the importance of validation when using register information for research purposes. In contrast, diagnoses obtained from the Danish National Vascular Registry had a high validity ready for use without further validation.