How do reproductive history and anthropometry in midlife relate to later risk of pelvic organ prolapse? A prospective cohort study.

INTRODUCTION AND HYPOTHESIS: The objective was to examine the association between reproductive and anthropometric factors and later risk of pelvic organ prolapse (POP). METHODS: We carried out a prospective cohort study including 11,114 female nurses > 44 years from the Danish Nurse Cohort. In 1993, the study population was recruited through the Danish Nurse Organization and self-reported data on age, height, weight, age at menarche, age at first birth and number of childbirths were obtained. POP diagnosis was obtained from the National Patient Registry. Risk of POP was estimated using COX regression and presented as hazard ratios (HR) with 95% confidence intervals (CI). RESULTS: Overall, 10% of the women received a diagnosis of POP within a median follow-up of 22 years. A 4% increase in risk of POP was seen for each increasing BMI (kg/m2) unit at baseline. Compared to women of normal weight, higher risks of POP were seen in overweight (HR 1.18: 1.02-1.36) and obese women (HR 1.33: 1.02-1.74), while underweight had a lower risk (HR 0.51: 0.27-0.95). Compared to women with one childbirth, women with no childbirths had a reduced risk of 57% while increased risks of 46%, 78% and 137% were observed in women with two, three and four childbirths. Women with menarche before the age of 12 tended to have a higher risk of POP as did women who were 30-33 years at their first childbirth. CONCLUSIONS: POP is a common health problem in women, and BMI and number of childbirths are strong predictors.

Type of menopause, age of menopause and variations in the risk of incident cardiovascular disease: pooled analysis of individual data from 10 international studies.

STUDY QUESTION: How does the risk of cardiovascular disease (CVD) vary with type and age of menopause? SUMMARY ANSWER: Earlier surgical menopause (e.g. <45 years) poses additional increased risk of incident CVD events, compared to women with natural menopause at the same age, and HRT use reduced the risk of CVD in women with early surgical menopause. WHAT IS KNOWN ALREADY: Earlier age at menopause has been linked to an increased risk of CVD mortality and all-cause mortality, but the extent that this risk of CVD varies by type of menopause and the role of postmenopausal HRT use in reducing this risk is unclear. STUDY DESIGN, SIZE, DURATION: Pooled individual-level data of 203 767 postmenopausal women from 10 observational studies that contribute to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE) consortium were included in the analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Postmenopausal women who had reported menopause (type and age of menopause) and information on non-fatal CVD events were included. Type of menopause (natural menopause and surgical menopause) and age at menopause (categorised as <35, 35-39, 40-44, 45-49, 50-54 and ≥55 years) were exposures of interest. Natural menopause was defined as absence of menstruation over a period of 12 months (no hysterectomy and/or oophorectomy) and surgical menopause as removal of both ovaries. The study outcome was the first non-fatal CVD (defined as either incident coronary heart disease (CHD) or stroke) event ascertained from hospital medical records or self-reported. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% CI for non-fatal CVD events associated with natural menopause and surgical menopause. MAIN RESULTS AND THE ROLE OF CHANCE: Compared with natural menopause, surgical menopause was associated with over 20% higher risk of CVD (HR 1.22, 95% CI 1.16-1.28). After the stratified analysis by age at menopause, a graded relationship for incident CVD was observed with lower age at menopause in both types of natural and surgical menopause. There was also a significant interaction between type of menopause and age at menopause (P < 0.001). Compared with natural menopause at 50-54 years, women with surgical menopause before 35 (2.55, 2.22-2.94) and 35-39 years (1.91, 1.71-2.14) had higher risk of CVD than those with natural menopause (1.59, 1.23-2.05 and 1.51, 1.33-1.72, respectively). Women who experienced surgical menopause at earlier age (<50 years) and took HRT had lower risk of incident CHD than those who were not users of HRT. LIMITATIONS, REASONS FOR CAUTION: Self-reported data on type and age of menopause, no information on indication for the surgery (e.g. endometriosis and fibroids) and the exclusion of fatal CVD events may bias our results. WIDER IMPLICATIONS OF THE FINDINGS: In clinical practice, women who experienced natural menopause or had surgical menopause at an earlier age need close monitoring and engagement for preventive health measures and early diagnosis of CVD. Our findings also suggested that timing of menopause should be considered as an important factor in risk assessment of CVD for women. The findings on CVD lend some support to the position that elective bilateral oophorectomy (surgical menopause) at hysterectomy for benign diseases should be discouraged based on an increased risk of CVD. STUDY FUNDING/COMPETING INTEREST(S): InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). GDM is supported by Australian National Health and Medical Research Council Principal Research Fellowship (APP1121844). There are no competing interests.

Night work and incidence of Parkinson's disease in the Danish Nurse Cohort.

OBJECTIVES: Evidence on the association between night work and Parkinson's disease (PD) is sparse and conflicting, calling for more definitive studies. METHODS: We included 20 138 female nurses from the Danish Nurse Cohort without PD who at baseline in 1993 and/or 1999 reported their most common current work schedule (day, evening, night, and rotating (a combination of at least two of these)), including information on lifetime cumulative duration (years) of each shift in a 2009 follow-up survey. We obtained information on PD hospital contacts and PD medication until November 2018 via linkage to the Danish National Patient (inpatient from 1977 and outpatient contacts from 1995 onwards) and Prescription Registers starting in 1995. We defined the incidence of PD as the first-ever hospital contact due to PD, or the first-ever redeemed levodopa prescription, whichever came first. We used Cox regression models to calculate HRs and 95% CIs, adjusting for age, smoking status, coffee consumption and use of hormone replacement therapy. RESULTS: We found no significant difference in PD risk among nurses who reported working evening (HR=0.86; 95% CI=0.55 to 1.34), night (HR=1.26; 95% CI=0.79 to 2.02) or rotating shifts (HR=0.83; 95% CI=0.56 to 1.21) at cohort baseline in 1993 or 1999, when compared with permanent day workers. Similarly, persistency of shift work (working the same work schedule for 6+ years) or duration of shift work was not associated with PD risk. CONCLUSIONS: Overall, there was little evidence for an association between various shift work schedules including night work and PD in this cohort of middle-aged female nurses.

Shift work and incidence of dementia: A Danish Nurse Cohort study.

INTRODUCTION: A few studies suggest that working night and rotating shifts increase the risk of dementia. We examined the association between shift work and the incidence of dementia in a cohort of female Danish nurses. METHODS: We linked Danish Nurse Cohort participants, who reported work schedules (day, evening, night, rotating shifts) in 1993 and/or 1999 and their duration in 2009, to Danish registers to obtain information on dementia hospitalizations and prescription medication until November 2018. RESULTS: Among 6048 nurses who reported work schedules in 1993 and 1999, nurses working night shifts ≥6 years had higher dementia incidence (hazard ratio: 2.43, 95% confidence interval: 1.39 to 4.23) than those working day shifts ≥6 years. Among 8059 nurses who reported shift work duration, nurses working night shifts ≥6 years had higher dementia incidence than those working night shifts <1 year (1.47, 1.06 to 2.06). DISCUSSION: Persistent night shift work may increase the risk of dementia.

Road traffic noise and markers of adiposity in the Danish Nurse Cohort: A cross-sectional study.

BACKGROUND: Studies have suggested that traffic noise is associated with markers of obesity. We investigated the association of exposure to road traffic noise with body mass index (BMI) and waist circumference in the Danish Nurse Cohort. METHODS: We used data on 15,501 female nurses (aged >44 years) from the nationwide Danish Nurse Cohort who, in 1999, reported information on self-measured height, weight, and waist circumference, together with information on socioeconomic status, lifestyle, work and health. Road traffic noise at the most exposed façade of the residence was estimated using Nord2000 as the annual mean of a weighted 24-h average (Lden). We used multiple linear regression models to examine associations of road traffic noise levels in 1999 (1-year mean) with BMI and waist circumference, adjusting for potential confounders, and evaluated effect modification by degree of urbanization, air pollution levels, night shift work, job strain, sedative use, sleep aid use, and family history of obesity. RESULTS: We did not observe associations between road traffic noise (per 10 dB increase in the 1-year mean Lden) and BMI (kg/m2) (ß: 0.00; 95% confidence interval (CI): -0.07, 0.07) or waist circumference (cm) (ß: -0.09; 95% CI: -0.31, 0.31) in the fully adjusted model. We found significant effect modification of job strain and degree of urbanization on the associations between Lden and both BMI and waist circumference. Job strained nurses were associated with a 0.41 BMI-point increase, (95% CI: 0.06, 0.76) and a 1.00 cm increase in waist circumference (95% CI: 0.00, 2.00). Nurses living in urban areas had a statistically significant positive association of Lden with BMI (ß: 0.26; 95% CI: 0.11, 0.42), whilst no association was found for nurses living in suburban and rural areas. CONCLUSION: Our results suggest that road traffic noise exposure in nurses with particular susceptibilities, such as those with job strain, or living in urban areas, may lead to increased BMI, a marker of adiposity.

Long-term exposure to road traffic noise and incidence of breast cancer: a cohort study.

BACKGROUND: Exposure to road traffic noise was associated with increased risk of estrogen receptor (ER)-negative (ER-) breast cancer in a previous cohort study, but not with overall or ER-positive (ER+) breast cancer, or breast cancer prognosis. We examined the association between long-term exposure to road traffic noise and incidence of breast cancer, overall and by ER and progesterone receptor (PR) status. METHODS: We used the data from a nationwide Danish Nurse Cohort on 22,466 female nurses (age > 44 years) who at recruitment in 1993 or 1999 reported information on breast cancer risk factors. We obtained data on the incidence of breast cancer from the Danish Cancer Registry, and on breast cancer subtypes by ER and PR status from the Danish Breast Cancer Cooperative Group, up to 31 December 2012. Road traffic noise levels at the nurses' residences were estimated by the Nord2000 method between 1970 and 2013 as annual means of a weighted 24 h average (Lden) at the most exposed facade. We used time-varying Cox regression to analyze the associations between the 24-year, 10-year, and 1-year mean of Lden and breast cancer, separately for total breast cancer and by ER and PR status. RESULTS: Of the 22,466 women, 1193 developed breast cancer in total during 353,775 person-years of follow up, of whom 611 had complete information on ER and PR status. For each 10 dB increase in 24-year mean noise levels at their residence, we found a statistically significant 10% (hazard ratio and 95% confidence interval 1.10; 1.00-1.20) increase in total breast cancer incidence and a 17% (1.17; 1.02-1.33) increase in analyses based on 611 breast cancer cases with complete ER and PR information. We found positive, statistically significant association between noise levels and ER+ (1.23; 1.06-1.43, N = 494) but not ER- (0.93; 0.70-1.25, N = 117) breast cancers, and a stronger association between noise levels and PR+ (1.21; 1.02-1.42, N = 393) than between noise levels and PR- (1.10; 0.89-1.37, N = 218) breast cancers. Association between noise and ER+ breast cancer was statistically significantly stronger in nurses working night shifts (3.36; 1.48-7.63) than in those not working at night (1.21; 1.02-1.43) (p value for interaction = 0.05). CONCLUSION: Long-term exposure to road traffic noise may increase risk of ER+ breast cancer.

Relationships between intensity, duration, cumulative dose, and timing of smoking with age at menopause: A pooled analysis of individual data from 17 observational studies.

BACKGROUND: Cigarette smoking is associated with earlier menopause, but the impact of being a former smoker and any dose-response relationships on the degree of smoking and age at menopause have been less clear. If the toxic impact of cigarette smoking on ovarian function is irreversible, we hypothesized that even former smokers might experience earlier menopause, and variations in intensity, duration, cumulative dose, and age at start/quit of smoking might have varying impacts on the risk of experiencing earlier menopause. METHODS AND FINDINGS: A total of 207,231 and 27,580 postmenopausal women were included in the cross-sectional and prospective analyses, respectively. They were from 17 studies in 7 countries (Australia, Denmark, France, Japan, Sweden, United Kingdom, United States) that contributed data to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). Information on smoking status, cigarettes smoked per day (intensity), smoking duration, pack-years (cumulative dose), age started, and years since quitting smoking was collected at baseline. We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CIs) for the associations between each smoking measure and categorised age at menopause (<40 (premature), 40-44 (early), 45-49, 50-51 (reference), and ≥52 years). The association with current and former smokers was analysed separately. Sensitivity analyses and two-step meta-analyses were also conducted to test the results. The Bayesian information criterion (BIC) was used to compare the fit of the models of smoking measures. Overall, 1.9% and 7.3% of women experienced premature and early menopause, respectively. Compared with never smokers, current smokers had around twice the risk of experiencing premature (RRR 2.05; 95% CI 1.73-2.44) (p < 0.001) and early menopause (1.80; 1.66-1.95) (p < 0.001). The corresponding RRRs in former smokers were attenuated to 1.13 (1.04-1.23; p = 0.006) and 1.15 (1.05-1.27; p = 0.005). In both current and former smokers, dose-response relationships were observed, i.e., higher intensity, longer duration, higher cumulative dose, earlier age at start smoking, and shorter time since quitting smoking were significantly associated with higher risk of premature and early menopause, as well as earlier menopause at 45-49 years. Duration of smoking was a strong predictor of age at natural menopause. Among current smokers with duration of 15-20 years, the risk was markedly higher for premature (15.58; 11.29-19.86; p < 0.001) and early (6.55; 5.04-8.52; p < 0.001) menopause. Also, current smokers with 11-15 pack-years had over 4-fold (4.35; 2.78-5.92; p < 0.001) and 3-fold (3.01; 2.15-4.21; p < 0.001) risk of premature and early menopause, respectively. Smokers who had quit smoking for more than 10 years had similar risk as never smokers (1.04; 0.98-1.10; p = 0.176). A limitation of the study is the measurement errors that may have arisen due to recall bias. CONCLUSIONS: The probability of earlier menopause is positively associated with intensity, duration, cumulative dose, and earlier initiation of smoking. Smoking duration is a much stronger predictor of premature and early menopause than others. Our findings highlight the clear benefits for women of early smoking cessation to lower their excess risk of earlier menopause.

Female reproductive history and risk of type 2 diabetes: A prospective analysis of 126 721 women.

AIM: To examine the prospective associations between aspects of a woman's reproductive history and incident diabetes. METHODS: We pooled individual data from 126 721 middle-aged women from eight cohort studies contributing to the International Collaboration for a Life Course Approach to Reproductive Health and Chronic Disease Events (InterLACE). Associations between age at menarche, age at first birth, parity and menopausal status with incident diabetes were examined using generalized linear mixed models, with binomial distribution and robust variance. We stratified by body mass index (BMI) when there was evidence of a statistical interaction with BMI. RESULTS: Over a median follow-up of 9 years, 4073 cases of diabetes were reported. Non-linear associations with diabetes were observed for age at menarche, parity and age at first birth. Compared with menarche at age 13 years, menarche at ≤10 years was associated with an 18% increased risk of diabetes (relative risk [RR] 1.18, 95% confidence interval [CI] 1.02-1.37) after adjusting for BMI. After stratifying by BMI, the increased risk was only observed in women with a BMI ≥25 kg/m2 . A U-shaped relationship was observed between parity and risk of diabetes. Compared with pre-/peri-menopausal women, women with a hysterectomy/oophorectomy had an increased risk of diabetes (RR 1.17, 95% CI 1.07-1.29). CONCLUSIONS: Several markers of a woman's reproductive history appear to be modestly associated with future risk of diabetes. Maintaining a normal weight in adult life may ameliorate any increase in risk conferred by early onset of menarche.

Body mass index and age at natural menopause: an international pooled analysis of 11 prospective studies.

Current evidence on the association between body mass index (BMI) and age at menopause remains unclear. We investigated the relationship between BMI and age at menopause using data from 11 prospective studies. A total of 24,196 women who experienced menopause after recruitment was included. Baseline BMI was categorised according to the WHO criteria. Age at menopause, confirmed by natural cessation of menses for ≥ 12 months, was categorised as < 45 years (early menopause), 45-49, 50-51 (reference category), 52-53, 54-55, and ≥ 56 years (late age at menopause). We used multinomial logistic regression models to estimate multivariable relative risk ratios (RRRs) and 95% confidence intervals (CI) for the associations between BMI and age at menopause. The mean (standard deviation) age at menopause was 51.4 (3.3) years, with 2.5% of the women having early and 8.1% late menopause. Compared with those with normal BMI (18.5-24.9 kg/m2), underweight women were at a higher risk of early menopause (RRR 2.15, 95% CI 1.50-3.06), while overweight (1.52, 1.31-1.77) and obese women (1.54, 1.18-2.01) were at increased risk of late menopause. Overweight and obesity were also significantly associated with around 20% increased risk of menopause at ages 52-53 and 54-55 years. We observed no association between underweight and late menopause. The risk of early menopause was higher among obese women albeit not significant (1.23, 0.89-1.71). Underweight women had over twice the risk of experiencing early menopause, while overweight and obese women had over 50% higher risk of experiencing late menopause.

Early menarche, nulliparity and the risk for premature and early natural menopause.

STUDY QUESTION: Are parity and the timing of menarche associated with premature and early natural menopause? SUMMARY ANSWER: Early menarche (≤11 years) is a risk factor for both premature menopause (final menstrual period, FMP <40 years) and early menopause (FMP 40-44 years), a risk that is amplified for nulliparous women. WHAT IS KNOWN ALREADY: Women with either premature or early menopause face an increased risk of chronic conditions in later life and of early death. Findings from some studies suggest that early menarche and nulliparity are associated with early menopause, however overall the evidence is mixed. Much of the evidence for a direct relationship is hampered by a lack of comparability across studies, failure to adjust for confounding factors and inadequate statistical power. STUDY DESIGN, SIZE, DURATION: This pooled study comprises 51 450 postmenopausal women from nine observational studies in the UK, Scandinavia, Australia and Japan that contribute to the International collaboration for a Life course Approach to reproductive health and Chronic disease Events (InterLACE). PARTICIPANTS/MATERIALS, SETTING, METHODS: Age at menarche (categorized as ≤11, 12, 13, 14 and 15 or more years) and parity (categorized as no children, one child and two or more children) were exposures of interest. Age at FMP was confirmed by at least 12 months of cessation of menses where this was not the result of an intervention (such as surgical menopause due to bilateral oophorectomy or hysterectomy) and categorized as premature menopause (FMP before age 40), early menopause (FMP 40-44 years), 45-49 years, 50-51 years, 52-53 years and 54 or more years. We used multivariate multinomial logistic regression models to estimate relative risk ratio (RRR) and 95% CI for associations between menarche, parity and age at FMP adjusting for within-study correlation. MAIN RESULTS AND THE ROLE OF CHANCE: The median age at FMP was 50 years (interquartile range 48-53 years), with 2% of the women experiencing premature menopause and 7.6% early menopause. Women with early menarche (≤11 years, compared with 12-13 years) were at higher risk of premature menopause (RRR 1.80, 95% CI 1.53-2.12) and early menopause (1.31, 1.19-1.44). Nulliparity was associated with increased risk of premature menopause (2.26, 1.84-2.77) and early menopause (1.32, 1.09-1.59). Women having early menarche and nulliparity were at over 5-fold increased risk of premature menopause (5.64, 4.04-7.87) and 2-fold increased risk of early menopause (2.16, 1.48-3.15) compared with women who had menarche at ≥12 years and two or more children. LIMITATIONS, REASONS FOR CAUTION: Most of the studies (except the birth cohorts) relied on retrospectively reported age at menarche, which may have led to some degree of recall bias. WIDER IMPLICATIONS OF THE FINDINGS: Our findings support early monitoring of women with early menarche, especially those who have no children, for preventive health interventions aimed at mitigating the risk of adverse health outcomes associated with early menopause. STUDY FUNDING/COMPETING INTEREST(S): InterLACE project is funded by the Australian National Health and Medical Research Council project grant (APP1027196). G.D.M. is supported by Australian Research Council Future Fellowship (FT120100812). There are no competing interests.

Self-rated health and cancer risk - a prospective cohort study among Danish women.

BACKGROUND: Self-rated health (SRH) has been shown to be a strong predictor of mortality from a number of major chronic diseases, however, the association with cancer remains unclear. The aim of this study was to investigate a possible association between change in SRH and cancer incidence. MATERIALS AND METHODS: SRH and information on lifestyle and other risk factors were obtained for 13-636 women in the Danish Nurse Cohort. Cancers that developed during 12 years of follow-up were identified in the National Patient Registry. An association between SRH and cancer was examined in a Cox proportional hazards model with adjustment for age, smoking, alcohol, marital status, physical activity, body mass index and estrogen replacement therapy. RESULTS: No significant association was found between SRH and overall cancer incidence in the age-adjusted Cox proportional hazards model (1.04; 95% CI 0.93-1.16), even after adjustment for potential confounding factors (HR 1.08; 95% CI 0.96-1.21). Likewise, there was no significant association between SRH and breast cancer (HR 1.09; 95% CI 0.89-1.33), lung cancer (HR 1.03; 95% CI 0.71-1.49) or colon cancer (HR 1.08; 95% CI 0.75-1.54). CONCLUSION: SRH is not significantly associated with the incidence of all cancers or breast, lung or colon cancer among Danish female nurses. Women who reported a decrease in SRH between 1993 and 1999 had the same risk for cancer as those who reported unchanged or improved SRH.

Classification of a palliative care population in a comprehensive cancer centre.

PURPOSE: The purposes of the present study were to classify the palliative care population (PCP) in a comprehensive cancer centre by using information on antineoplastic treatment options and to analyse associations between socio-demographic factors, cancer diagnoses, treatment characteristics and receiving specialist palliative care (SPC). METHODS: This is a cross-sectional screening study of patients with cancer in the Department of Oncology, Rigshospitalet, Copenhagen University Hospital for 6 months. Patients were assessed to be included in the DOMUS study: a randomised controlled trial of accelerated transition to SPC at home (NCT01885637). The PCP was classified as patients with incurable cancer and limited or no antineoplastic treatment options. Patients with performance status 2-4 were further classified as the essential palliative care population (EPCP). RESULTS: During the study period, 3717 patients with cancer were assessed. The PCP comprised 513 patients yielding a prevalence of 14 %. The EPCP comprised 256 patients (7 %). The EPCP was older, more likely inpatients, had a higher comorbidity burden and 38 % received SPC. Women, patients without caregivers and patients with breast cancer were more likely to receive SPC. CONCLUSIONS: By using objective criteria from clinical data and systematic screening, the observed prevalence of the PCP of 14 % may be generalisable to comprehensive cancer centres with similar composition of cancer diagnoses.

Long-term exposure to road traffic noise and all-cause and cause-specific mortality: a Danish Nurse Cohort study.

BACKGROUND: Long-term road traffic noise exposure is linked to cardio-metabolic disease morbidity, whereas evidence on mortality remains limited. OBJECTIVES: We investigated association of long-term exposure to road traffic noise with all-cause and cause-specific mortality. METHODS: We linked 22,858 females from the Danish Nurse Cohort (DNC), recruited into the Danish Register of Causes of Death up to 2014. Road traffic noise levels since 1970 were modelled by Nord2000 as the annual mean of a weighted 24 h average (Lden). Cox regression models examined the associations between Lden (5-year and 23-year means) and all-cause and cause-specific mortalities, adjusting for lifestyle and exposure to PM2.5 (particulate matter with diameter < 2.5 µm) and NO2 (nitrogen dioxide). RESULTS: During follow-up (mean 17.4 years), 3902 nurses died: 1622 from cancer, 922 from CVDs (289 from stroke), 338 from respiratory diseases (186 from chronic obstructive pulmonary disease, 114 from lower respiratory tract infections [ALRIs]), 234 from dementia, 95 from psychiatric disorders, and 79 from diabetes. Hazard ratios (95% confidence intervals) for all-cause mortality from fully-adjusted models were 1.06 (1.01, 1.11) and 1.09 (1.03, 1.15) per 10 dB of 5-year and 23-year mean Lden, respectively, which attenuated slightly in our main model (fully-adjusted plus PM2.5: 1.04 [1.00, 1.10]; 1.08 [1.02, 1.13]). Main model estimates suggested the strongest associations between 5-year mean Lden and diabetes (1.14: 0.81, 1.61), ALRIs (1.13: 0.84, 1.54), dementia (1.12: 0.90, 1.38), and stroke (1.10: 0.91, 1.31), whereas associations with 23-year mean Lden were suggested for respiratory diseases (1.15: 0.95, 1.39), psychiatric disorders (1.11: 0.78, 1.59), and all cancers (1.08: 0.99, 1.17). DISCUSSION: Among the female nurses from the DNC, we observed that long-term exposure to road traffic noise led to premature mortality, independently of air pollution, and its adverse effects may extend well beyond those on the cardio-metabolic system to include respiratory diseases, cancer, neurodegenerative and psychiatric disorders.

Shift work and incidence of psychiatric disorders: The Danish Nurse Cohort study.

BACKGROUND: Research on health effects of shift work has especially focused on somatic diseases, such as breast cancer and cardiometabolic disease, while less attention has been given to the association between shift work and mental health. METHODS: We used information on 19 964 female nurses (≥44 years) from the Danish Nurse Cohort, who reported current work schedule (day, evening, night, or rotating) at recruitment (1993/1999). In 5102 nurses who participated in both cohort waves, we defined persistent night shift work as working night shift in 1993 and 1999. We used Cox regression models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs), adjusting for relevant confounders. Through linkage of cohort participants to national registers, we defined incidence of mood and neurotic disorders as first hospital contact or redeemed prescription until November 2018. RESULTS: We found association between night shift work with mood disorders (HR = 1.31; 95%CI = 1.17-1.47) and neurotic disorders (1.29; 1.17-1.42), compared to day work. Associations were enhanced in nurses with persistent night shift work (1.85; 1.43-2.39 and 1.62; 1.26-2.09 for mood and neurotic disorders, respectively) and in nurses with specialist confirmed mood (1.69; 1.24-2.29) and neurotic (1.72; 1.22-2.44) disorders. Nurses with preexisting psychiatric disorders and full-time work seemed most susceptible. CONCLUSIONS: Night shift work is associated with increased risk of major psychiatric disorders. The novel suggestive findings of vulnerable groups, including nurses with a history of psychiatric disorders and full-time workers, are based on a limited number of cases, and further research is needed to confirm the results.

PEP-CoV protocol: a PEP flute-self-care randomised controlled trial to prevent respiratory deterioration and hospitalisation in early COVID-19.

INTRODUCTION: Infection with SARS-CoV-2 may progress to severe pulmonary disease, COVID-19. Currently, patients admitted to hospital because of COVID-19 have better prognosis than during the first period of the pandemic due to improved treatment. However, the overall societal susceptibility of being infected makes it pivotal to prevent severe courses of disease to avoid high mortality rates and collapse of the healthcare systems. Positive expiratory pressure (PEP) self-care is used in chronic pulmonary disease and has been shown to prevent pneumonia in a high-risk cohort of patients with leukaemia. PEP flute self-care to prevent respiratory deterioration and hospitalisation in early COVID-19: a randomised trial (The PEP-CoV trial) examines the effectiveness on respiratory symptoms and need of hospital admission by regular PEP flute use among non-hospitalised individuals with confirmed SARS-CoV-2 infection and COVID-19 symptoms. METHODS AND ANALYSIS: In this randomised controlled trial, we hypothesise that daily PEP flute usage as add-on to usual care is superior to usual care as regards symptom severity measured by the COPD Assessment Test (CAT) at 30-day follow-up (primary outcome) and hospital admission through register data (secondary outcome). We expect to recruit 400 individuals for the trial. Participants in the intervention group receive a kit of 2 PEP flutes and adequate resistances and access to instruction videos. A telephone hotline offers possible contact to a nurse. The eight-item CAT score measures cough, phlegm, chest tightness, dyspnoea, activities of daily living at home, feeling safe at home despite symptoms, sleep quality and vigour. The CAT score is measured daily in both intervention and control arms by surveys prompted through text messages. ETHICS AND DISSEMINATION: The study was registered prospectively at www.clinicaltrials.gov on 27 August 2020 (NCT04530435). Ethical approval was granted by the local health research ethics committee (Journal number: H-20035929) on 23 July 2020. Enrolment of participants began on 6 October 2020. Results will be published in scientific journals. TRIAL REGISTRATION NUMBER: NCT04530435; Pre-results.

Effect of PEP flute self-care versus usual care in early covid-19: non-drug, open label, randomised controlled trial in a Danish community setting.

OBJECTIVE: To determine whether positive expiratory pressure (PEP) by PEP flute self-care is effective in reducing respiratory symptoms among community dwelling adults with SARS-CoV-2 infection and early stage covid-19. DESIGN: Non-drug, open label, randomised controlled trial. SETTING: Capital Region and Region Zealand in Denmark from 6 October 2020 to 26 February 2021. PARTICIPANTS: Community dwelling adults, able to perform self-care, with a new SARS-CoV-2 infection (verified by reverse transcription polymerase chain reaction tests) and symptoms of covid-19. INTERVENTION: Participants were randomised to use PEP flute self-care in addition to usual care or have usual care only. Randomisation was based on permuted random blocks in a 1:1 ratio, stratified for sex and age (<60 or ≥60 years). The PEP self-care group was instructed to use a PEP flute three times per day during the 30 day intervention. MAIN OUTCOME MEASURES: Primary outcome was a change in symptom severity from baseline to day 30, as assessed by the self-reported COPD (chronic obstructive pulmonary disease) assessment test (CAT), which was adjusted for baseline values and stratification factors. Participants completed the CAT test questionnaire every day online. Secondary outcomes were self-reported urgent care visits due to covid-19, number of covid-19 related symptoms, and change in self-rated health, all within 30-days' follow-up. RESULTS: 378 participants were assigned to the PEP flute self-care intervention (n=190) or usual care only (n=188). In the PEP self-care group, the median number of days with PEP flute use was 21 days (interquartile range 13-25). For the intention-to-treat population, a group difference was observed in changes from baseline in CAT scores of -1.2 points (95% confidence interval -2.1 to -0.2; P=0.017) in favour of the PEP flute self-care group. At day 30, the PEP flute self-care group also reported less chest tightness, less dyspnoea, more vigour, and higher level of daily activities, but these differences were small, and no consistent effects were seen on the secondary outcomes. No serious adverse events were reported. CONCLUSIONS: In community dwelling adults with early covid-19, PEP flute self-care had a significant, yet marginal and uncertain clinical effect on respiratory symptom severity, as measured by CAT scores. TRIAL REGISTRATION: ClinicalTrials.gov NCT04530435.

Meta-analysis for individual participant data with a continuous exposure: A case study.

OBJECTIVE: Methods for meta-analysis of studies with individual participant data and continuous exposure variables are well described in the statistical literature but are not widely used in clinical and epidemiological research. The purpose of this case study is to make the methods more accessible. STUDY DESIGN AND SETTING: A two-stage process is demonstrated. Response curves are estimated separately for each study using fractional polynomials. The study-specific curves are then averaged pointwise over all studies at each value of the exposure. The averaging can be implemented using fixed effects or random effects methods. RESULTS: The methodology is illustrated using samples of real data with continuous outcome and exposure data and several covariates. The sample data set, segments of Stata and R code, and outputs are provided to enable replication of the results. CONCLUSION: These methods and tools can be adapted to other situations, including for time-to-event or categorical outcomes, different ways of modelling exposure-outcome curves, and different strategies for covariate adjustment.

Long-term low-level ambient air pollution exposure and risk of lung cancer - A pooled analysis of 7 European cohorts.

BACKGROUND/AIM: Ambient air pollution has been associated with lung cancer, but the shape of the exposure-response function - especially at low exposure levels - is not well described. The aim of this study was to address the relationship between long-term low-level air pollution exposure and lung cancer incidence. METHODS: The "Effects of Low-level Air Pollution: a Study in Europe" (ELAPSE) collaboration pools seven cohorts from across Europe. We developed hybrid models combining air pollution monitoring, land use data, satellite observations, and dispersion model estimates for nitrogen dioxide (NO2), fine particulate matter (PM2.5), black carbon (BC), and ozone (O3) to assign exposure to cohort participants' residential addresses in 100 m by 100 m grids. We applied stratified Cox proportional hazards models, adjusting for potential confounders (age, sex, calendar year, marital status, smoking, body mass index, employment status, and neighborhood-level socio-economic status). We fitted linear models, linear models in subsets, Shape-Constrained Health Impact Functions (SCHIF), and natural cubic spline models to assess the shape of the association between air pollution and lung cancer at concentrations below existing standards and guidelines. RESULTS: The analyses included 307,550 cohort participants. During a mean follow-up of 18.1 years, 3956 incident lung cancer cases occurred. Median (Q1, Q3) annual (2010) exposure levels of NO2, PM2.5, BC and O3 (warm season) were 24.2 µg/m3 (19.5, 29.7), 15.4 µg/m3 (12.8, 17.3), 1.6 10-5m-1 (1.3, 1.8), and 86.6 µg/m3 (78.5, 92.9), respectively. We observed a higher risk for lung cancer with higher exposure to PM2.5 (HR: 1.13, 95% CI: 1.05, 1.23 per 5 µg/m3). This association was robust to adjustment for other pollutants. The SCHIF, spline and subset analyses suggested a linear or supra-linear association with no evidence of a threshold. In subset analyses, risk estimates were clearly elevated for the subset of subjects with exposure below the EU limit value of 25 µg/m3. We did not observe associations between NO2, BC or O3 and lung cancer incidence. CONCLUSIONS: Long-term ambient PM2.5 exposure is associated with lung cancer incidence even at concentrations below current EU limit values and possibly WHO Air Quality Guidelines.

Smoking cessation prolongs survival in female cancer survivors - the Danish nurse cohort.

PURPOSE: To explore smoking cessation between cancer survivors and cancer-free women, and the potential survival benefits from smoking cessation in cancer surviving women. METHOD: We pooled 46,334 responses from the Danish Nurse Cohort. The cohort consists of female nurses, who were invited for surveys in 1993, 1999 and 2009. Participants were linked to nationwide registries on hospitalization, cause of death and migration through 2016. Odds for smoking cessation by cancer diagnosis were computed in propensity score matched logistic regression models, while survival by postdiagnosis smoking cessation was estimated in cox proportional hazards models. RESULTS: Eligible for analysis were 7841 women (mean age = 56.7 years, SD ± 7.2), who were smokers at baseline and survived to the next follow-up survey. Of these, 545 women were diagnosed with cancer and matched by propensity score (1:2) with 1090 cancer-free women. Odds for smoking cessation were significantly higher in cancer-diagnosed women compared to their cancer-free peers (OR = 1.31, 95% CI: 1.06-1.61). Moreover, mortality risk was significantly lower among cancer survivors who stopped smoking (HR = 0.64, 95% CI: 0.46-0.91), compared to persistent smokers. CONCLUSIONS: The results suggest considerable survival benefits from smoking cessation in cancer surviving female nurses, and that the time surrounding cancer diagnosis may serve as a teachable moment for smoking cessation. However, due to substantial methodological limitations embedded in the study, careful interpretation of the presented results is warranted. Future studies are needed to demonstrate the effects of diagnosis on smoking cessation as well as the effects of smoking cessation on survival in female cancer populations.

Long-term exposure to low levels of air pollution and mortality adjusting for road traffic noise: A Danish Nurse Cohort study.

BACKGROUND: The association between air pollution and mortality is well established, yet some uncertainties remain: there are few studies that account for road traffic noise exposure or that consider in detail the shape of the exposure-response function for cause-specific mortality outcomes, especially at low-levels of exposure. OBJECTIVES: We examined the association between long-term exposure to particulate matter [(PM) with a diameter of <2.5 µm (PM2.5), <10 µm (PM10)], and nitrogen dioxide (NO2) and total and cause-specific mortality, accounting for road traffic noise. METHODS: We used data on 24,541 females (age > 44 years) from the Danish Nurse Cohort, who were recruited in 1993 or 1999, and linked to the Danish Causes of Death Register for follow-up on date of death and its cause, until the end of 2013. Annual mean concentrations of PM2.5, PM10, and NO2 at the participants' residences since 1990 were estimated using the Danish DEHM/UBM/AirGIS dispersion model, and annual mean road traffic noise levels (Lden) were estimated using the Nord2000 model. We examined associations between the three-year running mean of PM2.5, PM10, and NO2 with total and cause-specific mortality by using time-varying Cox Regression models, adjusting for individual characteristics and residential road traffic noise. RESULTS: During the study period, 3,708 nurses died: 843 from cardiovascular disease (CVD), 310 from respiratory disease (RD), and 64 from diabetes. In the fully adjusted models, including road traffic noise, we detected associations of three-year running mean of PM2.5 with total (hazard ratio; 95% confidence interval: 1.06; 1.01-1.11), CVD (1.14; 1.03-1.26), and diabetes mortality (1.41; 1.05-1.90), per interquartile range of 4.39 µg/m3. In a subset of the cohort exposed to PM2.5 < 20 µg/m3, we found even stronger association with total (1.19; 1.11-1.27), CVD (1.27; 1.01-1.46), RD (1.27; 1.00-1.60), and diabetes mortality (1.44; 0.83-2.48). We found similar associations with PM10 and none with NO2. All associations were robust to adjustment for road traffic noise. DISCUSSION: Long-term exposure to low-levels of PM2.5 and PM10 is associated with total mortality, and mortality from CVD, RD, and diabetes. Associations were even stronger at the PM2.5 levels below EU limit values and were independent of road traffic noise.