Long-term exposure to road traffic noise and acute lower respiratory infections in the Danish Nurse Cohort.

BACKGROUND: Long-term exposure to road traffic noise is associated with cardiovascular disease, but the evidence on respiratory diseases is just emerging. We aimed to examine the association between long-term exposure to road traffic noise and the incidence of acute lower respiratory infections (ALRIs) in adults. METHODS: We followed 23,141 female nurses (age ≥ 44 years) from the Danish Nurse Cohort from baseline (1993 or 1999) to their first hospital contact (inpatient, outpatient, or emergency room) for ALRI, death, emigration or the end of 2015. The residential annual mean levels of road traffic noise (Lden) during the follow-up were estimated using the Nord2000 model. We applied time-varying Cox models to estimate the association of 3-year mean exposure to Lden with ALRIs incidence and piecewise analysis to estimate the threshold of Lden. We examined the robustness of the results by adjusting for residential exposure to air pollution, and the effect modification by attained age, socioeconomic status (SES), comorbidity, and lifestyle. RESULTS: During 18.5 years of follow-up, 2,004 nurses developed ALRIs. In a linear model, we detected a statistically significant positive association between Lden and ALRI, with a hazard ratio (HR) of 1.11 (95 % confidence interval (CI): 1.04, 1.17) per 9.2 dB (interquartile range, IQR). We observed non-linear association with a threshold at 57 dB, above which the HR was 1.25 (95 % CI: 1.09, 1.43) per IQR. Further adjustment for PM2.5 reduced the HRs slightly to 1.21 (95 % CI: 1.04, 1.40). The associations were stronger for nurses with asthma, and in those with lowest SES. CONCLUSION: We present novel findings in support of the association between long-term exposure to road traffic noise and ALRIs, independent of air pollution, suggesting noise as a risk factor for infectious respiratory diseases.

Screening outcome of HPV-vaccinated women: Data from the Danish Trial23 cohort study.

BACKGROUND: Danish women-who were HPV-vaccinated as girls-are now reaching an age where they are invited to cervical cancer screening. Because of their expected lower cervical cancer risk, we must reassess our screening strategies. We analyzed Danish HPV-vaccinated women's outcomes after the first screening test at age 23. METHODS AND FINDINGS: Our study was embedded in Danish routine cytology-based screening. We conducted an observational study and included women born in 1994, offered the 4-valent HPV vaccine at age 14, and subsequently invited to screening at age 23. Cervical cytology was used for diagnostics and clinical management. Residual material was HPV tested with Cobas® 4800/6800. The most severe histology diagnosis within 795 days of screening was found through linkage with the Danish National Pathology Register. We calculated the number of women undergoing follow-up (repeated testing and/or colposcopy) per detected cervical intraepithelial neoplasia (CIN2+). A total of 6021 women were screened; 92% were HPV-vaccinated; 12% had abnormal cytology; 35% were high-risk HPV-positive, including 0.9% HPV16/18 positive, and 20% had follow-up. In women that were cytology-abnormal and HPV-positive (Cyt+/HPV+), 610 (98.5%) had been followed up, and 138 CIN2+ cases were diagnosed, resulting in 4.4 (95% CI 3.9-5.2) women undergoing follow-up per detected CIN2+. In contrast to recommendations, 182 (12.2%) cytology-normal and HPV-positive (Cyt-/HPV+) women were followed up within 795 days, and 8 CIN2+ cases were found, resulting in 22.8 (95% CI 13.3-59.3) women undergoing follow-up per detected CIN2+. CONCLUSION: Overall, HPV prevalence was high in HPV-vaccinated women, but HPV16/18 had largely disappeared. In the large group of cytology-normal and HPV-positive women, 23 had been followed up per detected CIN2+ case. Our data indicated that primary HPV screening of young HPV-vaccinated women would require very effective triage methods to avoid an excessive follow-up burden. TRIAL REGISTRATION: Trial registration number: NCT0304955.

Long-term exposure to air pollution and road traffic noise and incidence of dementia in the Danish Nurse Cohort.

INTRODUCTION: We examined the association of long-term exposure to air pollution and road traffic noise with dementia incidence in the Danish Nurse Cohort. METHODS: Female nurses were followed for dementia incidence (hospital contact or medication prescription) from 1993/1999 to 2020. Air pollution and road traffic noise levels were estimated at nurses' residences, and their associations with dementia were examined using Cox regression models. RESULTS: Of 25,233 nurses 1409 developed dementia. Particulate matter with a diameter of ≤2.5 µm (PM2.5) was associated with dementia incidence, after adjusting for lifestyle, socioeconomic status, and road traffic noise (hazard ratio [95% confidence interval] 1.35 [1.15-1.59] per interquartile range of 2.6 µg/m3). There was no association of PM2.5 with dementia in physically active nurses. Association with road traffic noise diminished after adjusting for PM2.5 (1.02 [0.93-1.11] per 7.6 dB). DISCUSSION: Long-term exposure to air pollution increases risk of dementia, and physical activity may moderate this risk. HIGHLIGHTS: Long-term exposure to air pollution was associated with increased risk of dementia among female nurses from the Danish Nurse Cohort. Association of air pollution with dementia was independent of road traffic noise. Association of road traffic noise with dementia diminished after adjusting for air pollution. Physical activity moderated adverse effects of air pollution on dementia.

Long-Term Exposure to Air Pollution and Risk of Acute Lower Respiratory Infections in the Danish Nurse Cohort.

RATIONALE: Air pollution is a major risk factor for chronic cardiorespiratory diseases, affecting both the immune and respiratory systems' functionality, while the epidemiological evidence on respiratory infections remains sparse. OBJECTIVE: We aimed to assess the association of long-term exposure to ambient air pollution with risk of developing new and recurrent ALRIs that characterized by persistently severe symptoms necessitating hospital contact, and identify the potential susceptible populations by socio-economic status (SES), smoking, physical activity status, overweight, and co-morbidity with chronic lung disease. METHODS: We followed 23,912 female nurses from the Danish Nurse Cohort (> 44 years) from baseline (1993 or 1999) until 2018 for the incident and recurrent ALRIs defined by hospital contact (in-, outpatient, and emergency room) data from the National Patient Register. Residential annual mean concentrations of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and black carbon (BC) were modelled using Danish DEHM/UBM/AirGIS system. We used marginal Cox models with time-varying exposures to assess the association of 3-year running-mean air pollution with incident and recurrent ALRIs and examine effect modification by age, socio-economic status (SES), smoking, physical activity, body mass index, and comorbidity with asthma or chronic obstructive pulmonary disease (COPD). RESULTS: During a 21.3 years mean follow-up, 4,746 ALRIs were observed, of which 2,553 were incident. We observed strong positive associations of all three pollutants with incident ALRIs, with hazard ratios and 95% confidence intervals of 1.19 (1.08-1.31) per 2.5 µg/m3 for PM2.5, 1.17 (1.11-1.24) per 8.0 µg/m3 for NO2, and 1.09 (1.05-1.12) per 0.3 µg/m3 for BC, and slightly stronger associations with recurrent ALRIs. Associations were strongest in COPD patients and nurses with low physical activity. CONCLUSION: Long-term exposure to air pollution at low levels was associated with risk of new and recurrent ALRIs, with COPD patients and physically inactive subjects most vulnerable. Primary Source of Funding: This study was supported by the Novo Nordisk Foundation Challenge Programme (NNF17OC0027812).

Lifetime exposure to air pollution and academic achievement: A nationwide cohort study in Denmark.

Recent research suggests a link between air pollution and cognitive development in children, and studies on air pollution and academic achievement are emerging. We conducted a nationwide cohort study in Denmark to explore the associations between lifetime exposure to air pollution and academic performance in 9th grade. The study encompassed 785,312 children born in Denmark between 1989 and 2005, all of whom completed 9th-grade exit examinations. Using linear mixed models with a random intercept for each school, we assessed the relationship between 16 years of exposure to PM2.5, PM10, and gaseous pollutants and Grade Point Averages (GPA) in exit examinations, covering subjects such as Danish literature, Danish writing, English, mathematics, and natural sciences. The study revealed that a 5 µg/m3 increase in PM2.5 and PM10 was associated with a decrease of 0.99 (95 % Confidence Intervals: -1.05, -0.92) and 0.46 (-0.50, -0.41) in GPA, respectively. Notably, these negative associations were more pronounced in mathematics and natural sciences compared to language-related subjects. Additionally, girls and children with non-Danish mothers were found to be particularly susceptible to the adverse effects of air pollution exposure. These results underscore the potential long-term consequences of air pollution on academic achievement, emphasizing the significance of interventions that foster healthier environments for children's cognitive development.

Self-Reported Health as Predictor of Allostatic Load and All-Cause Mortality: Findings From the Lolland-Falster Health Study.

Objectives: The aim was to determine the association between self-reported health (SRH), allostatic load (AL) and mortality. Methods: Data derived from the Lolland-Falster Health Study undertaken in Denmark from 2016-2020 (n = 14,104). Median follow-up time for death was 4.6 years where 456 participants died. SRH was assessed with a single question and AL by an index of ten biomarkers. Multinomial regression analysis were used to examine the association between SRH and AL, and Cox regression to explore the association between SRH, AL and mortality. Results: The risk of high AL increased by decreasing level of SRH. The ratio of relative risk (RRR) of having medium vs. low AL was 1.58 (1.11-2.23) in women reporting poor/very poor SRH as compared with very good SRH. For men it was 1.84 (1.20-2.81). For high vs. low AL, the RRR was 2.43 (1.66-3.56) in women and 2.96 (1.87-4.70) in men. The hazard ratio (HR) for all-cause mortality increased by decreasing SRH. For poor/very poor vs. very good SRH, the HR was 6.31 (2.84-13.99) in women and 3.92 (2.12-7.25) in men. Conclusion: Single-item SRH was able to predict risk of high AL and all-cause mortality.

Correlation between allostatic load index and cumulative mortality: a register-based study of Danish municipalities.

OBJECTIVES: The aim of this study was to examine population-based allostatic load (AL) indices as an indicator of community health across 14 municipalities in Denmark. DESIGN: Register-based study. SETTING: Data derived from: the Lolland-Falster Health Study, the Copenhagen General Population Study and the Danish General Suburban Population Study. Nine biomarkers (systolic blood pressure, diastolic blood pressure, pulse rate, total serum cholesterol, high-density lipoprotein cholesterol, waist-to-hip ratio, triglycerides, C-reactive protein and serum albumin) were divided into high-risk and low-risk values based on clinically accepted criteria, and the AL index was defined as the average between the nine values. All-cause mortality data were obtained from Statistics Denmark. PARTICIPANTS: We examined a total of 106 808 individuals aged 40-79 years. PRIMARY OUTCOME MEASURE: Linear regression models were performed to investigate the association between mean AL index and cumulative mortality risk. RESULTS: Mean AL index was higher in men (range 2.3-3.3) than in women (range 1.7-2.6). We found AL index to be strongly correlated with the cumulative mortality rate, correlation coefficient of 0.82. A unit increase in mean AL index corresponded to an increase in the cumulative mortality rate of 19% (95% CI 13% to 25%) for men, and 16% (95% CI 8% to 23%) for women but this difference was not statistically significant. The overall mean increase in cumulative mortality rate for both men and women was 17% (95% CI 14% to 20%). CONCLUSIONS: Our findings indicate the population-based AL index to be a strong indicator of community health, and suggest identification of targets for reducing AL.

Long-term exposure to air pollution and risk of SARS-CoV-2 infection and COVID-19 hospitalisation or death: Danish nationwide cohort study.

BACKGROUND: Early ecological studies have suggested links between air pollution and risk of coronavirus disease 2019 (COVID-19), but evidence from individual-level cohort studies is still sparse. We examined whether long-term exposure to air pollution is associated with risk of COVID-19 and who is most susceptible. METHODS: We followed 3 721 810 Danish residents aged ≥30 years on 1 March 2020 in the National COVID-19 Surveillance System until the date of first positive test (incidence), COVID-19 hospitalisation or death until 26 April 2021. We estimated residential annual mean particulate matter with diameter ≤2.5 µm (PM2.5), nitrogen dioxide (NO2), black carbon (BC) and ozone (O3) in 2019 by the Danish DEHM/UBM model, and used Cox proportional hazards regression models to estimate the associations of air pollutants with COVID-19 outcomes, adjusting for age, sex, individual- and area-level socioeconomic status, and population density. RESULTS: 138 742 individuals were infected, 11 270 were hospitalised and 2557 died from COVID-19 during 14 months. We detected associations of PM2.5 (per 0.53 µg·m-3) and NO2 (per 3.59 µg·m-3) with COVID-19 incidence (hazard ratio (HR) 1.10 (95% CI 1.05-1.14) and HR 1.18 (95% CI 1.14-1.23), respectively), hospitalisations (HR 1.09 (95% CI 1.01-1.17) and HR 1.19 (95% CI 1.12-1.27), respectively) and death (HR 1.23 (95% CI 1.04-1.44) and HR 1.18 (95% CI 1.03-1.34), respectively), which were strongest in the lowest socioeconomic groups and among patients with chronic respiratory, cardiometabolic and neurodegenerative diseases. We found positive associations with BC and negative associations with O3. CONCLUSION: Long-term exposure to air pollution may contribute to increased risk of contracting severe acute respiratory syndrome coronavirus 2 infection as well as developing severe COVID-19 disease requiring hospitalisation or resulting in death.

Impact of COVID-19 pandemic on breast and cervical cancer screening in Denmark: A register-based study.

Background: Denmark was one of the few countries where it was politically decided to continue cancer screening during the COVID-19 pandemic. We assessed the actual population uptake of mammography and cervical screening during this period. Methods: The first COVID-19 lockdown in Denmark was announced on 11 March 2020. To investigate possible changes in cancer screening activity due to the COVID-19 pandemic, we analysed data from the beginning of 2017 until the end of 2021. A time series analysis was carried out to discover possible trends and outliers in the screening activities in the period 2017-2021. Data on mammography screening and cervical screening were retrieved from governmental pandemic-specific monitoring of health care activities. Results: A brief drop was seen in screening activity right after the first COVID-19 lockdown, but the activity quickly returned to its previous level. A short-term deficit of 43% [CI -49 to -37] was found for mammography screening. A short-term deficit of 62% [CI -65 to -58] was found for cervical screening. Furthermore, a slight, statistically significant downward trend in cervical screening from 2018 to 2021 was probably unrelated to the pandemic. Other changes, for example, a marked drop in mammography screening towards the end of 2021, also seem unrelated to the pandemic. Conclusions: Denmark continued cancer screening during the pandemic, but following the first lockdown a temporary drop was seen in breast and cervical screening activity. Funding: Region Zealand (R22-A597).

Breast density and risk of breast cancer.

Early studies reported a 4- to 6-fold risk of breast cancer between women with extremely dense and fatty breasts. As most early studies were case-control studies, we took advantage of a population-based screening program to study density and breast cancer incidence in a cohort design. In the Capital Region, Denmark, women aged 50 to 69 are invited to screening biennially. Women screened November 2012 to December 2017 were included, and classified by BI-RADS density code, version 4, at first screen after recruitment. Women were followed up for incident breast cancer, including ductal carcinoma in situ (DCIS), to 2020 in nationwide pathology data. Rate ratios (RRs) and 95% confidence intervals (CI) were compared across density groups using Poisson-regression. We included 189 609 women; 1 067 282 person-years; and 4110 incident breast cancers/DCIS. Thirty-three percent of women had BI-RADS density code 1; 38% code 2; 24% code 3; 4.7% code 4; and missing 0.3%. Using women with BI-RADS density code 1 as baseline; women with code 2 had RR 1.69 (95% CI 1.56-1.84); women with code 3, RR 2.06 (95% CI 1.89-2.25); and women with code 4, RR 2.37 (95% CI 1.05-2.74). Results differed between observations accumulated during screening and above screening age. Our results indicated less difference in breast cancer risk across level of breast density than normally stated. Translated into absolute risk of breast cancer after age 50, we found a 6.2% risk for the one-third of women with lowest density, and 14.7% for the 5% of women with highest density.

Stringency of COVID-19 Containment Response Policies and Air Quality Changes: A Global Analysis across 1851 Cities.

The COVID-19 containment response policies (CRPs) had a major impact on air quality (AQ). These CRPs have been time-varying and location-specific. So far, despite having numerous studies on the effect of COVID-19 lockdown on AQ, a knowledge gap remains on the association between stringency of CRPs and AQ changes across the world, regions, nations, and cities. Here, we show that globally across 1851 cities (each more than 300 000 people) in 149 countries, after controlling for the impacts of relevant covariates (e.g., meteorology), Sentinel-5P satellite-observed nitrogen dioxide (NO2) levels decreased by 4.9% (95% CI: 2.2, 7.6%) during lockdowns following stringent CRPs compared to pre-CRPs. The NO2 levels did not change significantly during moderate CRPs and even increased during mild CRPs by 2.3% (95% CI: 0.7, 4.0%), which was 6.8% (95% CI: 2.0, 12.0%) across Europe and Central Asia, possibly due to population avoidance of public transportation in favor of private transportation. Among 1768 cities implementing stringent CRPs, we observed the most NO2 reduction in more populated and polluted cities. Our results demonstrate that AQ improved when and where stringent COVID-19 CRPs were implemented, changed less under moderate CRPs, and even deteriorated under mild CRPs. These changes were location-, region-, and CRP-specific.

Allostatic load as predictor of mortality: a cohort study from Lolland-Falster, Denmark.

OBJECTIVES: The purposes of the present study were to determine the association between (1) 10 individual biomarkers and all-cause mortality; and between (2) allostatic load (AL), across three physiological systems (cardiovascular, inflammatory, metabolic) and all-cause mortality. DESIGN: Prospective cohort study. SETTING: We used data from the Lolland-Falster Health Study undertaken in Denmark in 2016-2020 and used data on systolic blood pressure (SBP) and diastolic blood pressure (DBP), pulse rate (PR), waist-hip ratio (WHR) and levels of low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), triglycerides, glycated haemoglobin A1c (HbA1c), C-reactive protein (CRP) and serum albumin. All biomarkers were divided into quartiles with high-risk values defined as those in the highest (PR, WHR, triglycerides, HbA1c, CRP) or lowest (HDL-c, albumin) quartile, or a combination hereof (LDL-c, SBP, DBP). The 10 biomarkers were combined into a summary measure of AL index. Participants were followed-up for death for an average of 2.6 years. PARTICIPANTS: We examined a total of 13 725 individuals aged 18+ years. PRIMARY OUTCOME MEASURE: Cox proportional hazard regression (HR) analysis were performed to examine the association between AL index and mortality in men and women. RESULTS: All-cause mortality increased with increasing AL index. With low AL index as reference, the HR was 1.33 (95% CI: 0.89 to 1.98) for mid AL, and HR 2.37 (95% CI: 1.58 to 3.54) for high AL. CONCLUSIONS: Elevated physiological burden measured by mid and high AL index was associated with a steeper increase of mortality than individual biomarkers.

Risk of precancerous cervical lesions in women using a hormone-containing intrauterine device and other contraceptives: a register-based cohort study from Denmark.

STUDY QUESTION: Is the risk of high-grade precancerous cervical lesions and/or is the risk of lesion progression increased in users of a hormone-containing intrauterine device (HIUD) compared with users of other contraceptive methods. SUMMARY ANSWER: Women starting use of HIUD had the same subsequent risk of cervical intraepithelial neoplasia 3+ (CIN3+) as copper IUD (CIUD) users, and both groups tended to have lower risks than oral contraceptives (OC) users. WHAT IS KNOWN ALREADY: HIUDs may cause inflammatory and immunosuppressive changes that may potentially affect the risk of persistent human papillomavirus infection and precancerous cervical lesions. STUDY DESIGN, SIZE, DURATION: A Danish population-based cohort study was conducted using register data from 2008 to 2011 on 26-50-year-old users of HIUD (n = 60 551), CIUD (n = 30 303), or OC (n = 165 627). PARTICIPANTS/MATERIALS, SETTING, METHODS: Within each user group, women were divided into two groups; normal cytology or abnormal diagnosis before start of contraceptive use (baseline). Follow-up histology and cytology diagnoses were registered during the 5 years after baseline. Adjusted relative risks (aRR) and 95% CI were calculated for precancerous cervical lesions in HIUD users compared with CIUD and OC users. MAIN RESULTS AND THE ROLE OF CHANCE: Women with normal cytology at baseline: at follow-up HIUD users had the same risk of CIN3 or higher (3+) as CIUD users; aRR 1.08 (95% CI 0.94-1.22). For the HIUD and CIUD groups compared with OCs, the risks of CIN3+ were lower: aRR 0.63 (95% CI 0.57-0.69) and aRR 0.58 (95% CI 0.52-0.65), respectively. The same was observed for CIN2 risks: aRR 0.86 (95% CI 0.76-0.96) and aRR 0.68 (95% CI 0.58-0.79) for HIUD and CIUD groups, respectively. Women with abnormal diagnosis at baseline: a lower progression risk, except for CIN2+ at baseline, was observed in HIUD users compared with OC users. Similar progression risks were found in HIUD and CIUD users. There were no differences between the three contraceptive groups in persistence or regression of present lesions. LIMITATIONS, REASONS FOR CAUTION: We adjusted for age, education, and region of residence as a proxy for socio-economic factors. Data on smoking and sexual behavior were not available thus we cannot exclude some differences between the three user groups. WIDER IMPLICATIONS OF THE FINDINGS: These findings suggest that women may safely use HIUDs. STUDY FUNDING/COMPETING INTEREST(S): A.P. Møller Foundation for the Advancement of Medical Science, Else and Mogens Wedell-Wedellborgs Fund, Direktør Emil C. Hertz og Hustru Inger Hertz Fund, and the Fund for Development of Evidence Based Medicine in Private Specialized Practices. EL is principle investigator for a study with HPV-test-kits provided by Roche. The other authors have nothing to declare. TRIAL REGISTRATION NUMBER: N/A.

Reference intervals for 12 clinical laboratory tests in a Danish population: The Lolland-Falster Health Study.

Reference intervals (RIs), developed as part of the Nordic Reference Interval Project 2000 (NORIP) are widely used in most European laboratories. We aimed to examine the validity of the NORIP RIs by establishing RIs for 12 frequently used laboratory tests based on data from a local Danish population and compare these local RIs with the NORIP RIs. Using an a posteriori direct sampling approach, blood sample data were assessed from 11,138 participants aged 18+ years in the Lolland-Falster Health Study (LOFUS), of whom 2154 turned out to meet criteria for being healthy for inclusion in establishing RIs according to the NORIP methodology. The 2.5th and 97.5th percentiles were calculated for alanine aminotransferase (ALAT), albumin, alkaline phosphatase, bilirubin, creatinine, hemoglobin, high-density lipoprotein cholesterol, iron, low-density lipoprotein cholesterol, thrombocytes, total cholesterol, and triglycerides. When comparing our estimates with the NORIP, the lower reference limits (RLs) for bilirubin and iron were lower, and higher for ALAT, thrombocytes and triglycerides. Upper RLs were lower for albumin (males and females ≥70 years), bilirubin and iron, but higher for alkaline phosphatase, triglycerides and for creatinine in men. In LOFUS, approximately 20% of the participants were healthy and qualified for inclusion in the establishment of RIs. Several of the local RIs differed from the NORIP RIs.

Burden of prediabetes, undiagnosed, and poorly or potentially sub-controlled diabetes: Lolland-Falster health study.

BACKGROUND: This study aimed to investigate prevalence and risk factors for prediabetes, undiagnosed diabetes mellitus, poorly and potentially sub-controlled diabetes in a rural-provincial general adult population in Denmark. METHODS: Using cross-sectional data from the Lolland-Falster Health Study, we examined a total of 10,895 individuals aged 20 years and above. RESULTS: Prevalence of prediabetes was 5.8% (men: 6.1%; women: 5.5%); of undiagnosed diabetes 0.8% (men: 1.0%; women: 0.5%); of poorly controlled diabetes 1.2% (men: 1.5%; women: 0.8%); and of potentially sub-controlled diabetes 2% (men: 3.0%; women: 1.3%). In total, 9.8% of all participants had a diabetes-related condition in need of intervention; men at a higher risk than women; RR 1.41 (95% CI 1.26-1.58); person aged + 60 years more than younger; RR 2.66 (95% CI 2.34-3.01); obese more than normal weight person, RR 4.51 (95% CI 3.79-5.38); smokers more than non-smokers, RR 1.38 (95% CI 1.19-1.62); persons with self-reported poor health perception more than those with good, RR 2.59 (95% CI 2.13-3.15); low leisure time physical activity more than those with high, RR 2.64 (95% CI 2.17-3.22); and persons with self-reported hypertension more than those without, RR 3.28 (95% CI 2.93-3.68). CONCLUSIONS: In the Lolland-Falster Health Study, nearly 10% of participants had prediabetes, undiagnosed diabetes, poorly controlled, or potentially sub-controlled diabetes. The risk of these conditions was more than doubled in persons with self-reported poor health perception, self-reported hypertension, low leisure time physical activity, or measured obesity, and a large proportion of people with diabetes-related conditions in need of intervention can therefore be identified relatively easily.

High-grade cervical lesions after vaccination against human papillomavirus: A Danish cohort study.

INTRODUCTION: It is pertinent to evaluate the impact of vaccination against human papillomavirus (HPV) in real life. The aim of the study was to evaluate the real-life impact of HPV vaccination in the first birth cohort of Danish women offered free HPV vaccination as girls and invited to screening at the age of 23 years. MATERIAL AND METHODS: Women born in 1993 were offered free HPV vaccination at the age of 15 years but women born in 1983 have never been offered free HPV vaccination. We followed these two birth cohorts for 10 years from the age of 15 to after their first invitation to screening, and compared the risk of high-grade cervical intraepithelial neoplasia (CIN). Data were obtained from Danish national health registers. RESULTS: Vaccination coverage was 91% in the 1993 birth cohort and <0.1% in the 1983 cohort. Screening coverage was close to 80% in both cohorts. CIN2+ was detected in 4% of the 15 748 screened women born in 1983 and in 3% of the 19 951 screened women born in 1993. The risk of high-grade CIN was reduced by about 30% in the 1993 cohort compared with the 1983 cohort; for CIN2+ relative risk 0.74 (95% CI 0.66-0.82) and for CIN3+ relative risk 0.68 (95% CI 0.58-0.79). CONCLUSIONS: This study investigated the real-life impact of quadrivalent HPV vaccination by comparing a cohort of women offered HPV vaccination with a cohort of women not offered HPV vaccination. The observed decrease in the detection of high-grade cervical lesions following HPV vaccination is in line with results from the randomized trials and has important implications for future cervical screening of HPV vaccinated cohorts.

Breast cancer mortality and overdiagnosis after implementation of population-based screening in Denmark.

INTRODUCTION: Service breast cancer screening is difficult to evaluate because there is no unscreened control group. Due to a natural experiment, where 20% of women were offered screening in two regions up to 17 years before other women, Denmark is in a unique position. We utilized this opportunity to assess outcome of service screening. MATERIALS AND METHODS: Screening was offered in Copenhagen from 1991 and Funen from 1993 to women aged 50-69 years. We used difference-in-differences methodology with a study group offered screening; a historical control group; a regional control group; and a regional-historical control group, comparing breast cancer mortality and incidence, including ductal carcinoma in situ, between study and historical control group adjusted for changes in other regions, and calculating ratios of rate ratios (RRR) with 95% confidence intervals (CI). Data came from Central Population Register; mammography screening databases; Cause of Death Register; and Danish Cancer Register. RESULTS: For breast cancer mortality, the study group accumulated 1,551,465 person-years and 911 deaths. Long-term breast cancer mortality in Copenhagen was 20% below expected in absence of screening; RRR 0.80 (95% CI 0.71-0.90), and in Funen 22% below; RRR 0.78 (95% CI 0.68-0.89). Combined, cumulative breast cancer incidence in women followed 8+ years post-screening was 2.3% above expected in absence of screening; RRR 1.023 (95% CI 0.97-1.08). DISCUSSION: Benefit-to-harm ratio of the two Danish screening programs was 2.6 saved breast cancer deaths per overdiagnosed case. Screening can affect only breast cancers diagnosed in screening age. Due to high breast cancer incidence after age 70, only one-third of breast cancer deaths after age 50 could potentially be affected by screening. Increasing upper age limit could be considered, but might affect benefit-to-harm ratio negatively.

Impact of chronic diseases on effect of breast cancer screening.

BACKGROUND: Although breast cancer screening reduces breast cancer mortality at the population level, subgroups of women may benefit differently. We investigated the impact of health status on the effect of breast cancer screening. METHODS: The study included 181 299 women invited in two population-based screening programs in Denmark and 1 526 446 control subjects, followed from April 1981 to December 2014. Poisson regressions were used to compare the observed breast cancer mortality rate in women invited to screening with the expected rate in the absence of screening among women with and without chronic diseases. Chronic diseases were defined as any diagnosis in the Charlson Comorbidity Index during 4 years before the first invitation to screening. RESULTS: Almost 10% of women had chronic diseases before first invitation to screening. Whereas we observed a reduction in breast cancer mortality following invitation to screening of 28% (95% CI, 20% to 35%) among women without chronic diseases, only a 7% (95% CI, -39% to 37%) reduction was seen for women with chronic diseases (P-value for interaction = .22). For participants, the reduction, corrected for selection bias, was 35% (95% CI 16% to 49%) for women without, and 4% (95% CI -146% to 62%) for women with chronic diseases (P-value for interaction = .43). CONCLUSION: Our data indicate a marginal effect of mammography screening on breast cancer mortality in women with chronic diseases. If our results are confirmed in other populations, the presence of chronic diseases will be an important factor to take into consideration in personalized screening.

Mammographic Density and Screening Sensitivity, Breast Cancer Incidence and Associated Risk Factors in Danish Breast Cancer Screening.

BACKGROUND: Attention in the 2000s on the importance of mammographic density led us to study screening sensitivity, breast cancer incidence, and associations with risk factors by mammographic density in Danish breast cancer screening programs. Here, we summarise our approaches and findings. METHODS: Dichotomized density codes: fatty, equal to BI-RADS density code 1 and part of 2, and other mixed/dense data from the 1990s-were available from two counties, and BI-RADS density codes from one region were available from 2012/13. Density data were linked with data on vital status, incident breast cancer, and potential risk factors. We calculated screening sensitivity by combining data on screen-detected and interval cancers. We used cohorts to study high density as a predictor of breast cancer risk; cross-sectional data to study the association between life style factors and density, adjusting for age and body mass index (BMI); and time trends to study the prevalence of high density across birth cohorts. RESULTS: Sensitivity decreased with increasing density from 78% in women with BI-RADS 1 to 47% in those with BI-RADS 4. For women with mixed/dense compared with those with fatty breasts, the rate ratio of incident breast cancer was 2.45 (95% CI 2.14-2.81). The percentage of women with mixed/dense breasts decreased with age, but at a higher rate the later the women were born. Among users of postmenopausal hormone therapy, the percentage of women with mixed/dense breasts was higher than in non-users, but the patterns across birth cohorts were similar. The occurrence of mixed/dense breast at screening age decreased by a z-score unit of BMI at age 13-odds ratio (OR) 0.56 (95% CI 0.53-0.58)-and so did breast cancer risk and hazard ratio (HR) 0.92 (95% CI 0.84-1.00), but it changed to HR 1.01 (95% CI 0.93-1.11) when controlled for density. Age and BMI adjusted associations between life style factors and density were largely close to unity; physical activity OR 1.06 (95% CI 0.93-1.21); alcohol consumption OR 1.01 (95% CI 0.81-1.27); air pollution OR 0.96 (95% 0.93-1.01) per 20 µg/m3; and traffic noise OR 0.94 (95% CI 0.86-1.03) per 10 dB. Weak negative associations were seen for diabetes OR 0.61 (95% CI 0.40-0.92) and cigarette smoking OR 0.86 (95% CI 0.75-0.99), and a positive association was found with hormone therapy OR 1.24 (95% 1.14-1.35). CONCLUSION: Our data indicate that breast tissue in middle-aged women is highly dependent on childhood body constitution while adult life-style plays a modest role, underlying the need for a long-term perspective in primary prevention of breast cancer.