Association between travel distance and face-to-face consultations with general practitioners before an incident acute myocardial infarction: a nationwide register-based spatial epidemiological study.

OBJECTIVES: This study examined the association between travel distance to the general practitioner's (GP) office and no face-to-face GP consultation within 1 year before an incident acute myocardial infarction (AMI). DESIGN: A prospective cohort study using multilevel spatial logistic regression analysis of nationwide register data. SETTING: Nationwide study including contacts to GPs in Denmark prior to an incident AMI in 2005-2017. PARTICIPANTS: 121 232 adults (≥30 years) with incident AMI were included in the study. PRIMARY AND SECONDARY OUTCOMES MEASURES: The primary outcome was odds of not having a face-to-face GP consultation within 1 year before an incident AMI. RESULTS: In total, 13 108 (10.8%) of the 121 232 individuals with incident AMI had no face-to-face consultation with the GP within 1 year before the AMI. Population density modified the association between travel distance and no face-to-face GP consultation. Increased odds of no face-to-face GP consultation was observed for medium (25th-75th percentile/1123-5449 m) and long (>75th percentile/5449 m) compared with short travel distance (<25th percentile/1123 m) among individuals living in small cities (OR (95% credible intervals) of 1.19 (1.10 to 1.29) and 1.19 (1.06 to 1.33), respectively) and rural areas (1.46 (1.26 to 1.68) and 1.48 (1.29 to 1.68), respectively). No association was observed for individuals living in large cities and the capital. CONCLUSIONS: Travel distance above approximately 1 km was significantly associated with no face-to-face GP consultation before an incident AMI among individuals living in small cities and rural areas. The structure of the healthcare system should consider the importance of geographical distance between citizens and the GP in remote areas.

Development of geographic inequality in dental caries and its association with socioeconomic factors over an 18-year period in Denmark.

BACKGROUND: Few studies have examined the development of geographic and socioeconomic inequalities in caries over time or have simultaneously assessed individual-level socioeconomic position (SEP) and neighborhood-level factors as a multi-layered phenomenon influencing caries inequalities. This study examined (i) the trends in geographic inequalities in caries among adolescents in Denmark and (ii) how the association between SEP and caries has progressed over time, when accounting for individual and neighborhood-level confounding factors. METHODS: This nationwide repeated cross-sectional study included 15-year-olds in Denmark from 1995, 2003, and 2013 (n = 149,808). The outcome was caries experience (measured by the decayed, missing, and filled tooth surfaces [DMFS] index). The exposure of interest was SEP, indicated by the previous year's parental education, occupational social class, and (equivalized) disposable household income. Covariates included individual-level factors (immigration status, country of origin, number of children and persons in the family, and household type) and neighborhood (residence municipality)-level factors (Gini index; proportion of unemployed, low-educated, and unmarried/non-cohabiting individuals; proportion of single-parent households and households with overcrowding). Data sources included the Danish national dental and administrative social registers and Statistics Denmark's statistics database (StatBank). Data were analyzed using spatial and spatiotemporal modelling utilizing zero-inflated negative binomial regressions and integrated nested Laplace approximations for Bayesian parametric inference. Observed caries experience geo-maps of the Danish municipalities for 1995, 2003, and 2013 were created. RESULTS: Between 1995 and 2013, caries prevalence in the 15-year-olds declined sharply (1995, 71%; 2013, 45%). Caries experience declined in nearly all socioeconomic subgroups and municipalities. However, geographic inequalities persisted with higher caries levels largely concentrated in the relatively deprived areas of Denmark. Increasing relative socioeconomic inequalities in caries over time were observed with significant graded associations between SEP and caries despite adjustment for the various individual and neighborhood-level covariates and the effect of assessment year (e.g., 15-year-olds with parents having basic education had 1.91-fold [95% CI: 1.86-1.95] higher caries experience than those having parents with high education). CONCLUSIONS: Reducing these enduring inequalities will likely require additional resources and targeted supportive and preventive measures for adolescents from lower SEP backgrounds and those residing in municipalities with higher caries prevalence.

Geographical inequalities in the decreasing 28-day mortality following incident acute myocardial infarction: a Danish register-based cohort study, 1987-2016.

BACKGROUND: Mortality following acute myocardial infarction (AMI) has decreased in western countries for decades; however, it remains unknown whether the decrease is distributed equally across the population independently of residential location. This study investigated whether the observed decreasing 28-day mortality following an incident AMI in Denmark from 1987 to 2016 varied geographically at municipality level after accounting for sociodemographic characteristics. METHODS: A register-based cohort study design was used to investigate 28-day mortality among individuals with an incident AMI. Global spatial autocorrelation (within sub-periods) was analysed at municipality level using Moran's I. Analysis of spatio-temporal autocorrelation before and after adjusting for sociodemographic characteristics was performed using logistic regression and conditional autoregressive models with inference in a Bayesian setting. RESULTS: In total, 368,839 individuals with incident AMI were registered between 1987 and 2016 in Denmark; 128,957 incident AMIs were fatal. The 28-day mortality decreased over time at national level with an odds ratio of 0.788 (95% credible interval (0.784, 0.792)) per 5-year period after adjusting for sociodemographic characteristics. The decrease in the 28-day mortality was geographically unequally distributed across the country and in a geographical region in northern Jutland, the 28-day mortality decreased significantly slower (4-12%) than at national level. CONCLUSIONS: During the period from 1987 to 2016, the 28-day mortality following an incident AMI decreased substantially in Denmark. However, in a local geographical region, the 28-day mortality decreased significantly slower than in the rest of the country both before and after adjusting for sociodemographic differences. Efforts should be made to keep geographical trend inequalities in the 28-day mortality to a minimum.

Helicopter emergency medical services missions to islands and the mainland during a 3-year period in Denmark: a population-based study on patient and sociodemographic characteristics, comorbidity, and use of healthcare services.

BACKGROUND: The Danish Helicopter Emergency Medical Services (HEMS) is part of the Danish Emergency Medical Services System serving 5.7 million citizens with 1% living on islands not connected to the mainland by road. HEMS is dispatched based on pre-defined criteria including severity and urgency, and moreover to islands for less urgent cases, when rapid transport to further care is needed. The study aim was to characterize patient and sociodemographic factors, comorbidity and use of healthcare services for patients with HEMS missions to islands versus mainland. METHODS: Descriptive study of data from the HEMS database in a three-year period from 1 October 2014 to 30 September 2017. All missions in which a patient was either treated on scene or transported by HEMS were included. RESULTS: Of 5776 included HEMS missions, 1023 (17.7%) were island missions. In total, 90.2% of island missions resulted in patient transport by HEMS compared with 62.1% of missions to the mainland. Disease severity was serious or life-threatening in 34.7% of missions to islands compared with 65.1% of missions to mainland and less interventions were performed by HEMS on island missions. The disease pattern differed with more "Other diseases" registered on islands compared with the mainland where cardiovascular diseases and trauma were the leading causes of contact. Patients from islands were older than patients from the mainland. Sociodemographic characteristics varied between inhabiting island patients and mainland patients: more island patients lived alone, less were employed, more were retired, and more had low income. In addition, residing island patients had to a higher extend severe comorbidity and more contacts to general practitioners and hospitals compared with the mainland patients. CONCLUSIONS: HEMS missions to islands count for 17.7% of HEMS missions and 90.2% of island missions result in patient transport. The island patients encountered by HEMS are less severely diseased or injured and interventions are less frequently performed. Residing island patients are older than mainland patients and have lower socioeconomic position, more comorbidities and a higher use of health care services. Whether these socio-economic differences result in longer hospital stay or higher mortality is still to be investigated.

Joint mapping of cardiovascular diseases: comparing the geographic patterns in incident acute myocardial infarction, stroke and atrial fibrillation, a Danish register-based cohort study 2014-15.

BACKGROUND: Disease mapping aims at identifying geographic patterns in disease. This may provide a better understanding of disease aetiology and risk factors as well as enable targeted prevention and allocation of resources. Joint mapping of multiple diseases may lead to improved insights since e.g. similarities and differences between geographic patterns may reflect shared and disease-specific determinants of disease. The objective of this study was to compare the geographic patterns in incident acute myocardial infarction (AMI), stroke and atrial fibrillation (AF) using the unique, population-based Danish register data. METHODS: Incident AMI, stroke and AF was modelled by a multivariate Poisson model including a disease-specific random effect of municipality modelled by a multivariate conditionally autoregressive (MCAR) structure. Analyses were adjusted for age, sex and income. RESULTS: The study included 3.5 million adults contributing 6.8 million person-years. In total, 18,349 incident cases of AMI, 28,006 incident cases of stroke, and 39,040 incident cases of AF occurred. Estimated municipality-specific standardized incidence rates ranged from 0.76 to 1.35 for AMI, from 0.79 to 1.38 for stroke, and from 0.85 to 1.24 for AF. In all diseases, geographic variation with clusters of high or low risk of disease after adjustment was seen. The geographic patterns displayed overall similarities between the diseases, with stroke and AF having the strongest resemblances. The most notable difference was observed in Copenhagen (high risk of stroke and AF, low risk of AMI). AF showed the least geographic variation. CONCLUSION: Using multiple-disease mapping, this study adds to the results of previous studies by enabling joint evaluation and comparison of the geographic patterns in AMI, stroke and AF. The simultaneous mapping of diseases displayed similarities and differences in occurrence that are non-assessable in traditional single-disease mapping studies. In addition to reflecting the fact that AF is a strong risk factor for stroke, the results suggested that AMI, stroke and AF share some, but not all environmental risk factors after accounting for age, sex and income (indicator of lifestyle and health behaviour).

Geographical variation and clustering are found in atrial fibrillation beyond socioeconomic differences: a Danish cohort study, 1987-2015.

BACKGROUND: The prevalence and incidence rate of atrial fibrillation (AF) increase worldwide and AF is a risk factor for more adverse cardiovascular diseases including stroke. Approximately 44% of AF cases cannot be explained by common individual risk factors and risk might therefore also be related to the environment. By studying geographical variation and clustering in risk of incident AF adjusted for socioeconomic position at an individual level, potential neighbourhood risk factors could be revealed. METHODS: Initially, yearly AF incidence rates 1987-2015 were estimated overall and stratified by income in a register-based cohort study. To examine geographical variation and clustering in AF, we used both spatial scan statistics and a hierarchical Bayesian Poisson regression analysis of AF incidence rates with random effect of municipalities (n = 98) in Denmark in 2011-2015. RESULTS: The 1987-2015 cohort included 5,453,639 individuals whereof 369,800 were diagnosed with an incident AF. AF incidence rate increased from 174 to 576 per 100,000 person-years from 1987 to 2015. Inequality in AF incidence rate ratio between highest and lowest income groups increased from 23% in 1987 to 38% in 2015. We found clustering and geographical variation in AF incidence rates, with incidence rates at municipality level being up to 34% higher than the country mean after adjusting for socioeconomic position. CONCLUSIONS: Geographical variations and clustering in AF incidence rates exist. Compared to previous studies from Alberta, Canada and the United States, we show that geographical variations exist in a country with free access to healthcare and even when accounting for socioeconomic differences at an individual level. An increasing social inequality in AF was seen from 1987 to 2015. Therefore, when planning prevention strategies, attention to individuals with low income should be given. Further studies focusing on identification of neighbourhood risk factors for AF are needed.

Acute myocardial infarction: Does survival depend on geographical location and social background?

AIMS: This study described the interplay between geographical and social inequalities in survival after incident acute myocardial infarction (AMI) and examined whether geographical variation in survival exists when accounting for sociodemographic characteristics of the patients and their neighbourhood. METHODS: Ringmap visualization and generalized linear models were performed to study post-AMI mortality. Three individual-level analyses were conducted: immediate case fatality, mortality between days 1 and 28 after admission and 365-day survival among patients who survived 28 days after admission. RESULTS: In total, 99,013 incident AMI cases were registered between 2005 and 2014 in Denmark. Survival after AMI tended to correlate with sociodemographic indicators at the municipality level. In individual-level models, geographical inequality in immediate case fatality was observed with high mortality in northern parts of Jutland after accounting for sociodemographic characteristics. In contrast, no geographical variation in survival was observed among patients who survived 28 days. In all three analyses, odds and rates of mortality were higher among patients with low educational level (odds ratio (OR) (95% credible intervals) of 1.20 (1.12-1.29), OR of 1.12 (1.01-1.24) and mortality rate ratio of 1.45 (1.30-1.61)) and low income (OR of 1.24 (1.15-1.33), OR of 1.33 (1.20-1.48) and mortality rate ratio of 1.25 (1.13-1.38)). CONCLUSION: Marked geographical inequality was observed in immediate case fatality. However, no geographically unequal distribution of survival was found among patients who survived 28 days after AMI. Results additionally showed social inequality in survival following AMI.

Improving the cost-effectiveness of laypersons' paediatric basic life support skills training: A randomised non-inferiority study.

AIM: To compare dyad (training in pairs without an instructor) with resource-intensive instructor-led training for laypersons' paediatric resuscitation skills in a non-inferiority trial and examine cost-effectiveness of the training methods. METHODS: In this randomised parallel group non-inferiority trial, 155 dyad and 175 instructor-led laypersons were trained in Basic Life Support and Foreign Body Airway Obstruction Management. Dyads were given instructional videos, hands-on exercises and provided feedback to their partner for 50 min. Instructor-led laypersons trained in groups of six for two hours. Learning were assessed in scenarios immediately after training and, subsequently, at 14 days, 1, and 3 months. Pass rates, cost-effectiveness of producing a competent layperson (passing both tests), and non-inferiority were analysed. RESULTS: Sixty-eight (45.6%) dyad and 130 (74.3%) instructor-led laypersons passed the basic life support test (p < 0.001). For Foreign Body Airway Obstruction Management 77 (54.2%) dyad and 130 (79.3%) for instructor-led laypersons passed (p < 0.001). Skills decreased over three months for both groups. Forty-two (30.4%) dyad and ninety-eight (59.8%) for instructor-led laypersons were competent after training (p < 0.001). The lower effectiveness of dyad training had reduced costs (p < 0.001). For each 10,000 USD allocated to training, dyad training would result in 71 vs. 65 competent laypersons for instructor-led training. Non-inferiority of dyad training could not be established. CONCLUSION: Instructor-led training was the most effective but also the most expensive training method, making it less cost-effective than dyad training. When the aim is to train for quantity rather than quality, dyad training would be the preferred choice of training method.

Geographical inequalities in acute myocardial infarction beyond neighbourhood-level and individual-level sociodemographic characteristics: a Danish 10-year nationwide population-based cohort study.

OBJECTIVE: This study examined whether geographical patterns in incident acute myocardial infarction (AMI) were explained by neighbourhood-level and individual-level sociodemographic characteristics. DESIGN: An open cohort study design of AMI-free adults (age ≥30 years) with a residential location in Denmark in 2005-2014 was used based on nationwide administrative population and health register data linked by the unique personal identification number. Poisson regression of AMI incidence rates (IRs) with a geographical random effect component was performed using a Bayesian approach. The analysis included neighbourhood-level variables on income, ethnic composition, population density and population turnover and accounted for individual-level age, sex, calendar year, cohabitation status, income and education. SETTING: Residents in Denmark (2005-2014). PARTICIPANTS: The study population included 4 128 079 persons (33 907 796 person-years at risk) out of whom 98 265 experienced an incident AMI. OUTCOME MEASURE: Incident AMI registered in the National Patient Register or the Register of Causes of Death. RESULTS: Including individual and neighbourhood sociodemographic characteristics in the model decreased the variation in IRs of AMI. However, living in certain areas was associated with up to 40% increased IRs of AMI in the adjusted model and accounting for sociodemographic characteristics only moderately changed the geographical disease patterns. CONCLUSIONS: Differences in sociodemographic characteristics of the neighbourhood and individuals explained part, but not all of the geographical inequalities in incident AMI. Prevention strategies should address the confirmed social inequalities in incident AMI, but also target the areas with a heavy disease burden to enable efficient allocation of prevention resources.

Small-scale geographical variation in multiple sclerosis: A case-control study using Danish register data 1971-2013.

BACKGROUND: The aetiology of multiple sclerosis (MS) is largely unknown, but commonly assumed to be a complex interaction between genes and environmental exposures, presumably during early life. To evaluate the possible importance and timing of environmental exposures we investigated the spatial variation in the risk of MS in Denmark according to residence at birth, age 15, and clinical onset of disease. METHODS: We carried out a nationwide, register-based case-control study including 12 993 Danish MS cases with onset of disease 1971-2013. Information on exact residential addresses was available for all study subjects in the Danish Civil Registration System. The spatial variation in risk of MS was estimated by kernel regression. RESULTS: We identified spatial variation in the risk of MS according to residence at birth, age 15, and onset of disease. Several high- and low-risk areas were identified across the country with some variation between birth, age 15, and onset. CONCLUSIONS: Small-scale geographical variation in the risk of MS suggests that local environmental risk factors could be at play and may be related to life style factors.

Mortality in Danish Swine herds: Spatio-temporal clusters and risk factors.

The aim of this study was to explore spatio-temporal mortality patterns in Danish swine herds from December 2013 to October 2015, and to discuss the use of mortality data for syndromic surveillance in Denmark. Although it has previously been assessed within the context of syndromic surveillance, the value of mortality data generated on a regular and mandatory basis from all swine herds remains unexplored in terms of swine surveillance in Denmark. A total of 5010 farms were included in the analysis, corresponding to 1896 weaner herds, 1490 sow herds and 3839 finisher herds. The spatio-temporal analysis included data description for spatial, temporal, and spatio-temporal cluster analysis for three age groups: weaners (up to 30kg), sows and finishers. Logistic regression models were used to assess the potential factors associated with finisher and weaner herds being included within multiple-herd clusters. The spatio-temporal distribution of mortality changed over time, and suggested a general increase in mortality for the months of January and July for the three age groups. A large number of single-herd clusters (i.e. clusters with only one herd), and fewer multiple-herd clusters (i.e. clusters with at least two herds) were found. The herd size affected whether weaner herds were within multiple-herd clusters, and factors such farm type, SPF status and presence of atrophic rhinitis had an impact on finisher herds being inside vs. outside multiple-herd clusters in the univariable analysis. However, due to a strong correlation between variables, only farm type remained in the multivariable analysis for the finisher herds. The higher mortality observed for the months of January and July could be linked to infrequent updates of the data used to calculate mortality. The presence of single-herd clusters might indicate welfare and disease issues, while multiple-herd clusters could suggest the presence of infectious diseases within the cluster area. The impact of farm type is linked to the fact that larger farms specialize in only one age group, with high biosecurity and more specialized personnel, and subsequently a lower mortality. Mortality data have a potential use in disease surveillance. However, detected clusters might not be due to disease, but the result of changes such as herd management practices. Further analysis to explore other spatio-temporal monitoring methods is needed before mortality data can be incorporated into a Danish disease monitoring system.

Lithium in Drinking Water and Incidence of Suicide: A Nationwide Individual-Level Cohort Study with 22 Years of Follow-Up.

Suicide is a major public health concern. High-dose lithium is used to stabilize mood and prevent suicide in patients with affective disorders. Lithium occurs naturally in drinking water worldwide in much lower doses, but with large geographical variation. Several studies conducted at an aggregate level have suggested an association between lithium in drinking water and a reduced risk of suicide; however, a causal relation is uncertain. Individual-level register-based data on the entire Danish adult population (3.7 million individuals) from 1991 to 2012 were linked with a moving five-year time-weighted average (TWA) lithium exposure level from drinking water hypothesizing an inverse relationship. The mean lithium level was 11.6 µg/L ranging from 0.6 to 30.7 µg/L. The suicide rate decreased from 29.7 per 100,000 person-years at risk in 1991 to 18.4 per 100,000 person-years in 2012. We found no significant indication of an association between increasing five-year TWA lithium exposure level and decreasing suicide rate. The comprehensiveness of using individual-level data and spatial analyses with 22 years of follow-up makes a pronounced contribution to previous findings. Our findings demonstrate that there does not seem to be a protective effect of exposure to lithium on the incidence of suicide with levels below 31 µg/L in drinking water.

Geographical variation in a fatal outcome of acute myocardial infarction and association with contact to a general practitioner.

BACKGROUND: Geographical variation in incidence and mortality of acute myocardial infarction (AMI) is present in Denmark. We aimed at examining the association between contact to a general practitioner (GP) the year before AMI and a fatal outcome of AMI. METHODS: Register-based data and individual-level addresses including 69,608 individuals with AMI in 2006-2011. A Bayesian hierarchical logistic regression model was used to examine the association. RESULTS: A fatal outcome of AMI was seen among 12.0% (78%) of individuals with (without) contact to a GP the year before AMI. A significant association was estimated. CONCLUSIONS: A fatal outcome of AMI was significantly associated with contact to a GP. A high population to GP ratio and long distance to GP could not explain the increased odds of a fatal outcome of AMI for individuals with no contact to a GP.

Spatial pattern in prevalence of paratuberculosis infection diagnosed with misclassification in Danish dairy herds in 2009 and 2013.

Paratuberculosis is a chronic infection of economic importance to the dairy industry. The infection may be latent for years, which makes diagnostic misclassification a general challenge. The objective of this study was to identify the spatial pattern in infection prevalence, when results were adjusted for covariate information and diagnostic misclassification. Furthermore, we compared the estimated spatial pattern with the spatial pattern obtained without adjustment for misclassification. The study included 1242 herds in 2009 and 979 herds in 2013. The within-herd prevalence was modelled using a hierarchical logistic regression model and included a spatial component modelled by a continuous Gaussian field. The Stochastic Partial Differential Equation (SPDE) approach and Integrated Nested Laplace Approximation (INLA) were used for Bayesian inference. We found a significant spatial component, and our results suggested that the estimated range of influence and the overall location of areas with increased prevalence are not very sensitive to diagnostic misclassification.

Estimating range of influence in case of missing spatial data: a simulation study on binary data.

BACKGROUND: The range of influence refers to the average distance between locations at which the observed outcome is no longer correlated. In many studies, missing data occur and a popular tool for handling missing data is multiple imputation. The objective of this study was to investigate how the estimated range of influence is affected when 1) the outcome is only observed at some of a given set of locations, and 2) multiple imputation is used to impute the outcome at the non-observed locations. METHODS: The study was based on the simulation of missing outcomes in a complete data set. The range of influence was estimated from a logistic regression model with a spatially structured random effect, modelled by a Gaussian field. Results were evaluated by comparing estimates obtained from complete, missing, and imputed data. RESULTS: In most simulation scenarios, the range estimates were consistent with ≤25% missing data. In some scenarios, however, the range estimate was affected by even a moderate number of missing observations. Multiple imputation provided a potential improvement in the range estimate with ≥50% missing data, but also increased the uncertainty of the estimate. CONCLUSIONS: The effect of missing observations on the estimated range of influence depended to some extent on the missing data mechanism. In general, the overall effect of missing observations was small compared to the uncertainty of the range estimate.

Spatial correlation in Bayesian logistic regression with misclassification.

Standard logistic regression assumes that the outcome is measured perfectly. In practice, this is often not the case, which could lead to biased estimates if not accounted for. This study presents Bayesian logistic regression with adjustment for misclassification of the outcome applied to data with spatial correlation. The models assessed include a fixed effects model, an independent random effects model, and models with spatially correlated random effects modelled using conditional autoregressive prior distributions (ICAR and ICAR(ρ)). Performance of these models was evaluated in a simulation study. Parameters were estimated by Markov Chain Monte Carlo methods, using slice sampling to improve convergence. The results demonstrated that adjustment for misclassification must be included to produce unbiased regression estimates. With strong correlation the ICAR model performed best. With weak or moderate correlation the ICAR(ρ) performed best. With unknown spatial correlation the recommended model would be the ICAR(ρ), assuming convergence can be obtained.

Birth weight, childhood body mass index, and height in relation to mammographic density and breast cancer: a register-based cohort study.

INTRODUCTION: High breast density, a strong predictor of breast cancer may be determined early in life. Childhood anthropometric factors have been related to breast cancer and breast density, but rarely simultaneously. We examined whether mammographic density (MD) mediates an association of birth weight, childhood body mass index (BMI), and height with the risk of breast cancer. METHODS: 13,572 women (50 to 69 years) in the Copenhagen mammography screening program (1991 through 2001) with childhood anthropometric measurements in the Copenhagen School Health Records Register were followed for breast cancer until 2010. With logistic and Cox regression models, we investigated associations among birth weight, height, and BMI at ages 7 to 13 years with MD (mixed/dense or fatty) and breast cancer, respectively. RESULTS: 8,194 (60.4%) women had mixed/dense breasts, and 716 (5.3%) developed breast cancer. Childhood BMI was significantly inversely related to having mixed/dense breasts at all ages, with odds ratios (95% confidence intervals) ranging from 0.69 (0.66 to 0.72) at age 7 to 0.56 (0.53 to 0.58) at age 13, per one-unit increase in z-score. No statistically significant associations were detected between birth weight and MD, height and MD, or birth weight and breast cancer risk. BMI was inversely associated with breast cancer, with hazard ratios of 0.91 (0.83 to 0.99) at age 7 and 0.92 (0.84 to 1.00) at age 13, whereas height was positively associated with breast cancer risk (age 7, 1.06 (0.98 to 1.14) and age 13, 1.08 (1.00 to 1.16)). After additional adjustment for MD, associations of BMI with breast cancer diminished (age 7, 0.97 (0.88 to 1.06) and age 13, 1.01 (0.93 to 1.11)), but remained with height (age 7, 1.06 (0.99 to 1.15) and age 13, 1.09 (1.01 to 1.17)). CONCLUSIONS: Among women 50 years and older, childhood body fatness was inversely associated with the breast cancer risk, possibly via a mechanism mediated by MD, at least partially. Childhood tallness was positively associated with breast cancer risk, seemingly via a pathway independent of MD. Birth weight was not associated with MD or breast cancer in this age group.

Spatial differences in occurrence of paratuberculosis in Danish dairy herds and in control programme participation.

Paratuberculosis is a chronic infection of economic importance to the cattle industry and a voluntary control programme is offered to Danish dairy farmers. Our objective was to evaluate spatial differences in both control programme participation and paratuberculosis prevalence in Denmark. The study included 4414 dairy herds: 1249 were participating in the control programme, and 1503 were tested for antibodies to Mycobacterium avium subsp. paratuberculosis (MAP). Spatial differences were evaluated by kernel smoothing, kriging, and cluster analysis. Participation was lowest among herds on the island Zealand (≤23%). The risk of a herd being infected with MAP was found to be high on most of Zealand, but the uncertainty of this result was large due to a limited number of tested herds. In the rest of the country, the south western part of the peninsula Jutland had the highest risk of MAP (≥91%). The risk of MAP was also high (86-91%) in the northern part of both Jutland and Funen. The predicted apparent within-herd prevalence was highest (5-8.5%) in some local areas across Jutland, in the north western part of the island Funen, and in the south and western part of Zealand. Scan statistics located the primary cluster of herds with high apparent within-herd prevalence in the western part of Funen. Furthermore, a number of significant clusters were found in Jutland and a single significant cluster in Zealand. Consistency was found between kriging and scan statistics results with respect to location of areas with high apparent within-herd prevalence of MAP. Potential explanations for differences in participation include herd size and local herd health advisers, whereas for example soil characteristics might influence prevalence. Further studies are needed to evaluate these and other risk factors.

Trends in sickness absence in Denmark.

OBJECTIVE: Based on the prevailing view that it has become a more common behavior, sickness absence is -presently a topic of considerable concern in many European countries. Using sickness absence data from Denmark, we aimed to show whether this assumption holds true or not. METHODS: We used a linear regression analysis to analyze time trends in sickness absence based on datasets from the Danish Employers Confederation, the State Employer's Authority, the Labour Force Survey, and Statistics Denmark. RESULTS: The findings from the Confederation of Danish Employers, the State Employer's Authority, and the Labor Force Survey indicated a stable and largely unaltered pattern of sickness absence during the last 20 years. Findings from Statistics Denmark showed an increase in the cumulative incidence proportion from 6.6 to 7.5% among employed people between 2000 and 2007. CONCLUSION: Our data did not indicate that sickness absence behavior has become more common in Denmark during the past 20 years; although, an increase was seen in the beginning of this century. It is apparent that the many reports on sickness absence that highlight an increasing trend are based on sickness benefit reimbursement data and have overlooked the underlying changes over time in the risk population and the entitlement to reimbursement.

Performance of systematic and non-systematic ('opportunistic') screening mammography: a comparative study from Denmark.

OBJECTIVES: Evaluation and comparison of the performance of organized and opportunistic screening mammography. METHODS: Women attending screening mammography in Denmark in 2000. The study included 37,072 women attending organized screening. Among these, 320 women were diagnosed with breast cancer during follow-up. Opportunistic screening was attended by 2855 women with 26 women being diagnosed with breast cancer. Data on women attending screening were linked with information on cancer status. Each woman was followed with respect to diagnosis of breast cancer (invasive as well as in situ) for a period of two years. Screening outcome and cancer status during follow-up were combined to assess whether the result of the examination was true-positive, true-negative, false-positive or false-negative. Based on this classification, age-adjusted sensitivity and specificity of organized and opportunistic screening were calculated. RESULTS: Defining BI-RADS(trade mark) 4-5 as a positive screening outcome, the overall sensitivity of opportunistic screening was 33.6% and the specificity was 99.1%. Using BI-RADS(trade mark) 3-5 as positive, the sensitivity was 37.4% and the specificity was 97.9%. Organized screening (which was not categorized according to BI-RADS(trade mark)) had an overall sensitivity of 67.2% and a specificity of 98.4%. CONCLUSION: Our study showed a considerably higher sensitivity in organized screening than in opportunistic screening, while the specificity was fairly similar in the two settings. The findings support implementation of population-based breast screening programmes, as recommended in the 'European guidelines for quality assurance in breast cancer screening and diagnosis'.