Predicting long-term survival after de novo cardioverter-defibrillator implantation for primary prevention: A population based study.

Background: Implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden cardiac death in patients with left ventricular dysfunction. While short-term mortality benefit of ICD insertion has been established in landmark randomized controlled trials, little is known about the long-term outcomes of patients with ICDs in clinical practice. In this paper, we describe the long-term survival of patients following de novo ICD implantation for primary prevention in clinical practice and determine the factors which help predict survival after ICD implant. Methods: Retrospective population-based study of all patients receiving a de novo ICD for primary prevention in Ontario, Canada from 2007 to 2011 using the Ontario ICD Database housed within ICES. Simple random selection was used to split the population into a derivation and internal validation cohort in a ratio of 2:1. Cox proportional hazards regression was used to determine predictors of interest and predict 10-year survival, model performance was assessed using calibration and validation. Results: In the derivation cohort (n = 3399), mean age was 65.3 years (standard deviation [SD] = 11.0), 664 patients were female (19.5 %) and 2344 patients (69.0 %) had ischemic cardiomyopathy. Ten year survival was 45.7 % (95 % confidence interval [CI] 44.0 %-47.4 %). The final prediction model included age, sex, disease factors (ischemic vs nonischemic cardiomyopathy, left ventricular ejection fraction) and patient factors (symptoms, comorbidities), and biomarkers at the time of ICD assessment. This model had good discrimination and calibration in derivation (0.79, 95 % CI 0.77, 0.81) and validation samples (0.78, 95 % CI 0.76, 0.79). Conclusions: A combination of demographic and clinical factors determined at baseline can be used to predict 10-year survival in patients with implantable cardioverter-defibrillators with good accuracy. Our findings help to identify individuals at risk of long-term mortality and may be useful in targeting future prevention strategies to enhance longevity in this high-risk population.

The Impact of Primary Care Practice Models on Indicators of Unplanned Health Care Utilization for Ontario Adults Newly Diagnosed With Chronic Obstructive Pulmonary Disease: A Retrospective Cohort Study.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a highly prevalent chronic disease. Most of the care for this population occurs within the primary care setting; however, the extent to which different primary care practice models influence the outcomes of patients with COPD remains unclear. OBJECTIVE: The study aimed to compare and analyze the influence of different primary care practice models on indicators of unplanned health care utilization among newly diagnosed COPD patients in Ontario. DESIGN: A retrospective cohort study was conducted using health administrative database within the Institute for Clinical Evaluative Sciences. The cohort included persons who were 35 years and older with physician-diagnosed COPD between January 1, 2014 and December 31, 2019. Patients were assigned into 3 practice models: team-based, traditional, and no enrolment. The primary outcomes examined was unplanned health care utilization, specifically emergency department (ED) visits and hospitalizations. To account for excessive zero values, the zero inflated negative binomial (ZINB) models were used to analyze the association between different practice models and unplanned health care utilization. RESULTS: Among 57,145 individuals who met the inclusion criteria, 55,994 were included in the regression analysis. Of the included participants, 62.8% of patients were in the traditional group, 30.3% were in the team-based group, and 6.9% were in the no enrolment group. Between 2014 and 2019, 70.7% of the cohort had at least 1 all-cause ED visit without hospitalization. The adjusted ZINB models showed no significant difference in risks of experiencing an unplanned health care utilization between the team-based and traditional groups. However, patients in the no enrolment group had a significantly higher risk of ED visit without hospitalization regardless of cause, ED visit with hospitalization regardless of cause, and 30-day readmissions regardless of cause. CONCLUSIONS: Primary care practice models are complex, influenced by remuneration and organizational structures, reinforcing the need for further research to enhance our understanding of primary care reforms. Furthermore, given the growing shortage of primary care providers, patients with COPD and other chronic conditions are particularly vulnerable.

Identifying the effect of inherited bleeding disorders on the development of postpartum hemorrhage: a population-based, retrospective cohort study.

Background: Women with inherited bleeding disorders (IBDs) are at an increased risk of postpartum hemorrhage (PPH). However, the impact of other maternal predelivery risk factors, including anemia, on the association between IBD and maternal bleeding remains poorly understood. Additionally, studies examining potential pathways linking IBD and PPH are limited. Objectives: We aimed to determine the risk of PPH associated with IBD. Methods: A retrospective cohort study was conducted using data held within ICES (formerly the Institute for Clinical Evaluative Sciences). Women with an in-hospital, live, or stillborn delivery between January 2014 and December 2019 were included. Poisson regression with robust error variance was used to determine the risk (RR) and 95% CIs of PPH among women with or without an IBD diagnosis. Models were stratified for primiparous and multiparous women. Results: Among the total population of 601,773 women, 29,661 (4.93%) experienced PPH. Multivariate models demonstrated that IBD was an independent risk factor for PPH among both the total cohort (adjusted RR [aRR] = 1.26; 95% CI: 1.08, 1.46) and primiparous women (aRR = 1.36; 95% CI: 1.12, 1.66). Among multiparous women, prior PPH was associated with an increased risk of PPH (aRR = 8.65; 95% CI: 8.32, 8.99), whereas IBD had no effect (aRR = 1.1; 95% CI: 0.86, 1.4). Predelivery anemia, placental conditions, multifetal gestation, and induction of labor were associated with increased PPH risk among all cohorts. Conclusions: IBD significantly increases the risk of PPH. The management of delivery should be based on individualized assessment of risk factors to ensure optimal maternal outcomes.

Investigating the relationship between melatonin patterns and methylation in circadian genes among day shift and night shift workers.

OBJECTIVES: Mechanisms underlying the carcinogenicity of night shift work remain uncertain. One compelling yet understudied cancer mechanism may involve altered DNA methylation in circadian genes due to melatonin secretion patterns. The objective of this study was to explore the relationship between melatonin secretion patterns and circadian gene methylation among day and night shift workers. METHODS: Female healthcare employees (n=38 day workers, n=36 night shift workers) for whom we had urinary 6-sulfatoxymelatonin secretion data from a previous study were recontacted. New blood samples were collected and used to measure methylation levels at 1150 CpG loci across 22 circadian genes using the Illumina Infinium MethylationEPIC beadchip. Linear regression was used to examine the association between melatonin (acrophase and mesor) and M values for each CpG site (false discovery rate, q=0.2), while testing for effect modification by shift work status. RESULTS: Among night shift workers, a higher mesor (24 hours of mean production of melatonin) was associated with increased methylation in the body of RORA (q=0.02) and decreased methylation in the putative promoter region of MTNR1A (q=0.03). Later acrophase (ie, time of peak concentration) was associated with increased methylation in the putative promoter region of MTNR1A (q=0.20) and decreased methylation in the body of PER3 (q=0.20). No associations were identified among day workers. CONCLUSIONS: In conclusion, patterns in melatonin secretion were associated with differential circadian gene methylation among night shift workers. Melatonin and alteration of DNA methylation in circadian genes may be one pathway towards increased cancer risk, although larger-scale studies examining multiple time points are needed.

DNA methylation of circadian genes and markers of cardiometabolic risk in female hospital workers: An exploratory study.

Night shift work has been linked to increased risk of cardiovascular disease (CVD); however, the underlying mechanisms remain unclear. A compelling yet understudied mechanism involves differential DNA methylation of circadian genes. To investigate the relevance of this mechanism, we conducted an exploratory cross-sectional study of 74 female hospital personnel (38 day workers, 36 night shift workers). Sociodemographic, lifestyle, and health characteristics as well as shift work status and history were determined through self-report. Fasting blood samples were collected to measure markers of cardiometabolic risk and DNA was extracted to measure DNA methylation of 1150 cytosine-guanine (CpG) sites across 22 circadian genes. Associations between methylation levels at individual CpG sites (ß-values) and markers of cardiometabolic risk were analyzed while considering effect modification by shift work status. The false discovery rate was applied to account for multiple comparisons (q ≤ 0.20). Two CpG sites [cg06758649 (CRY1) and cg06899802 (CSNK1A1)] were differentially associated with waist circumference and body mass index by shift work status, and eight CpG sites [cg26103512 (CSNK1D), cg03941313 (CSNK1E), cg18217763 (CSNK1E), cg16682686 (DEC1), cg12061096 (RORA), cg10133825 (RORA), cg19652148 (RORA), and cg22904654 (RORA)] were differentially associated with LDL cholesterol concentration by shift work status (all q ≤ 0.20). Our findings suggest that the relationship between DNA methylation of circadian genes and cardiometabolic risk differs by day and night shift worker status, which may contribute to mechanisms of increased risk of CVD observed among night shift workers.

Exploring the impact of night shift work on methylation of circadian genes.

Night shift work is associated with increased breast cancer risk, but the molecular mechanisms are not well-understood. The objective of this study was to explore the relationship between night shift work parameters (current status, duration/years, and intensity) and methylation in circadian genes as a potential mechanism underlying the carcinogenic effects of night shift work. A cross-sectional study was conducted among 74 female healthcare employees (n = 38 day workers, n = 36 night shift workers). The Illumina Infinium MethylationEPIC beadchip was applied to DNA extracted from blood samples to measure methylation using a candidate gene approach at 1150 CpG loci across 22 circadian genes. Linear regression models were used to examine the association between night shift work parameters and continuous methylation measurements (ß-values) for each CpG site. The false-discovery rate (q = 0.2) was used to account for multiple comparisons. Compared to day workers, current night shift workers demonstrated hypermethylation in the 5'UTR region of CSNK1E (q = 0.15). Individuals that worked night shifts for ≥10 years exhibited hypomethylation in the gene body of NR1D1 (q = 0.08) compared to those that worked <10 years. Hypermethylation in the gene body of ARNTL was also apparent in those who worked ≥3 consecutive night shifts a week (q = 0.18). These findings suggest that night shift work is associated with differential methylation in core circadian genes, including CSNK1E, NR1D1 and ARNTL. Future, larger-scale studies with long-term follow-up and detailed night shift work assessment are needed to confirm and expand on these findings.

The Associations of Shift Work, Sleep Quality, and Incidence of Hypertension in Ontario Adults: A Population-Based Study.

BACKGROUND: Relatively few population-based studies have explored the relationship and potential mechanisms between exposure to shift work and hypertension. The study objectives for this study were to determine 1) if history of shift work was associated with increased rates of hypertension among working adults, and 2) if sleep quality mediated this relationship. METHODS: We conducted a population-based cohort study using data from Ontario respondents (aged 35-69 y) in the 2000-2001 Canadian Community Health Survey, which was linked to administrative health data housed at the Institute for Clinical Evaluative Sciences. Our sample included survey participants who were employed with no previous diagnosis of hypertension (n = 7420). During a 12-year follow-up window, we determined the time of hypertension diagnosis based on a previously validated algorithm; and explored the mediating effect of sleep quality using marginal structural effect models. RESULTS: The study sample included 2079 shift workers and 5341 day workers. Shift workers reported less refreshing sleep, more trouble sleeping, and poorer sleep quality overall compared with day workers. In 12 years of follow-up, 31.3% of workers developed hypertension. History of shift work was associated with higher hypertension rates in both men (hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.02-1.44) and women (HR 1.26, 95% CI 1.03-1.55). There was no evidence that these associations were mediated by past sleep quality. CONCLUSIONS: History of shift work schedules is associated with increased rates of hypertension. Shift work disrupts sleep, but further longitudinal studies are needed to determine if sleep quality mediates the association between shift work and hypertension.

Building Research Capacity in Nursing Academia in 2020: Is the Road Less Perilous?

BACKGROUND: Building research capacity in nursing academic units continues to be a challenge. There are a number of external contextual factors and internal factors that influence individual faculty as well as the collective to engage successfully in research. PURPOSE: The overall aim of this opinion article is to provide an overview of the current external and internal, processes and structures, relevant to capacity of nursing faculty to engage in research. METHODS: To inform the external context, we reviewed national research funding trends for nursing. To inform the internal context, we provided an exemplar of the internal processes and structures designed to support research capacity building within our academic unit. RESULTS: Canadian Institutes of Health Research funding trends for research grants led by nurse principal applicants increased between 2010 and 2013, followed by a steady decline. In 2017 to 2018, there were only 24 research grants led by nurse principal applicants. These external challenges coupled with the traditional internal barriers, such as the imbalance between teaching and research time, threaten research capacity for nursing academics. CONCLUSION: Organizational strategies to promote research capacity within academic nursing units are a necessary requirement to move forward.

A population-based study of prescribing trends in a potentially vulnerable paediatric population from 1999 to 2012.

OBJECTIVES: There is a limited understanding of paediatric medication prescribing trends and patterns, thus poorly positioning decision-makers to identify quality and safety concerns related to medication use. The objective of this study was to determine overall medication prescribing trends and patterns among children receiving Ontario Drug Benefits over a thirteen-year period in the province of Ontario, Canada. METHODS: Administrative health databases housed within the Institute for Clinical Evaluative Sciences (ICES), Ontario, Canada, were used to identify outpatient prescriptions dispensed from 1999 to 2012 through a publicly funded programme to children ≤18 years of age. Medications were classified according to the American Hospital Formulary Service Pharmacologic-Therapeutic Classification system. Descriptive statistics were used to summarize prescribing patterns. KEY FINDINGS: This study identified 457 037 children who were dispensed a new prescription between 1999 and 2012. About 56% received their first prescription before 6.5 years of age, and 85% of the children in this study were from families who received social assistance. The most commonly prescribed drugs were antiinfectives (56.1%). Prescriptions for several central nervous system agents, including antipsychotics and agents for attention-deficit/hyperactivity disorder, increased across the study period. Changes in prescribing patterns within opioids, hormones and autonomic agents were noted. The results suggest that historically, prescribing trends have shifted with public policy, pharmaceutical marketing and diagnostic patterns, thus identifying them as a possible tool to measure the impact of policydriven practice changes. Anti-infective prescribing increased markedly with the global H1N1 pandemic. Pharmaceutical marketing, formulary decisions and diagnostic trends may affect the prescribing of ADHD medications globally. The prescribing of codeine-containing products and medroxyprogesterone appeared to fluctuate in response to important publications in the medical literature, and the use of epinephrine syringes increased after public policy changes in the province of Ontario. The steady rise in the use of medications whose long-term effects in children are unknown, such as antipsychotics and proton pump inhibitors, identifies areas in need of future research. CONCLUSIONS: This study presents the first overview of Canadian prescribing trends for children, the majority of which are of low socioeconomic status and represent a potentially vulnerable population. Our analysis suggests that future research is required to determine whether prescribing trends could be used as indicators of policy effectiveness, pharmacovigilance and diagnostic trends.

Exploring the utility of the Nursing Role Effectiveness Model in evaluating nursing contributions in primary health care: A scoping review.

AIMS: To inform a discussion for the applicability of using the Nursing Role Effectiveness Model (NREM) in the primary health care setting through a synthesis of the literature that has used the model in all health care sectors. DESIGN: Scoping Review. METHODS: Articles were considered for inclusion if they discussed any aspect of the NREM in health care research that presented information related to any nursing regulatory designation, such as nurse practitioner (NP), registered nurse (RN), licensed/registered practical nurse (LPN/RPN) and considered both quantitative and qualitative study designs, including expert opinions and reports. RESULTS: A total of 22 articles that cited and/or used the NREM were identified in this review. Only two studies were focused in the primary health care setting. There is precedence for the use of the NREM to guide research in primary health care. The NREM should be modified to incorporate the unique characteristics of the primary health care setting.

A population profile of older adults with prescription encounters with nurse practitioners and family physicians in Ontario: a descriptive retrospective cohort study.

BACKGROUND: Compared with patients in family physician practices, there is a poor understanding at a population level of patients in nurse practitioner practices. The study aim was to use Ontario administrative databases to identify the sociodemographic characteristics and comorbidities of patients aged 65 years and older who were prescribed medications by nurse practitioners and family physicians between 2000 and 2015. METHODS: This population-based descriptive retrospective cohort study included patients 65 years of age and older with Ontario Health Insurance Plan eligibility and at least 1 prescription encounter with a nurse practitioner or family physician during the study period. Prescription identification of patients permitted their characterization by age, sex, geographical location, rurality, neighbourhood income and comorbidities. Patients were categorized into 3 provider groups on the basis of the percentage of prescription encounters with nurse practitioners versus family physicians. RESULTS: In 2015, patients in the study cohort with prescriptions by nurse practitioners (n = 25 220) were younger than those with prescriptions by family physicians (40.3% were aged 65-69 yr) and they were more likely to be residents of low-income neighbourhoods (44.0% were in the lowest 2 neighbourhood income quintiles) and to be living outside of central Ontario. In contrast, patients who received prescriptions from family physicians (n = 1 952 904) tended to be older (26.8% were aged ≥ 80 yr), to have higher incomes (21.1% were in the highest neighbourhood income quintile) and to live in urban areas (86.5%). Mean Elixhauser Comorbidity Index scores were consistently lower among patients cared for by nurse practitioners than among those predominantly seen by family physicians (1.30 v. 2.04). The most prevalent conditions were hypertension and diabetes, regardless of provider. INTERPRETATION: The patient characteristic with the highest variability between providers was geographic residence in the province. Elucidating patterns of care is critical for primary care policy and our results provide baseline data for future health care planning.

Characteristics of Nurse Practitioner Practice in Family Health Teams in Ontario, Canada.

Nurse practitioners (NPs) in Ontario work in a number of settings, including physician-led, interprofessional Family Health Teams (FHTs). However, many aspects of NP practice within the FHTs are unknown. Our study aimed to describe the characteristics of NP practice in FHTs and the relationships between NPs and physicians within this model. This cross-sectional descriptive study analyzed NP service and diagnostic code data collected for every NP patient encounter from 2012 to 2015. Encounter data were linked to health administrative data housed at the Institute for Clinical Evaluative Sciences to allow for comparison with physician service and diagnostic codes. Findings demonstrated that NPs saw patients across all age groups for one to more than five problems per encounter and that NPs handled both acute and episodic care and chronic disease management issues. Patients with chronic conditions had more encounters with physicians than with NPs. In addition, compared to physicians, NPs saw more female than male patients. Our findings provide a snapshot of NP practice in FHTs and may be useful in informing other practice models in Ontario, elsewhere in Canada, and internationally. More evidence is needed, however, to clarify the responsibilities of the NPs in collaborative relationships with physicians and to embed policies that will ensure that NPs work to their full potential. In addition, applying service coding to all health care providers in FHTs could enhance data on interprofessional teams and the individual clinicians that comprise them.

Trends in nurse practitioners' prescribing to older adults in Ontario, 2000-2010: a retrospective cohort study.

BACKGROUND: Nurse prescribing is a practice that has evolved and will continue to evolve in response to emerging trends, particularly in primary care. The goal of this study was to describe the trends and patterns in medication prescription to adults 65 years of age or older in Ontario by nurse practitioners over a 10-year period. METHODS: We conducted a population-based descriptive retrospective cohort study. All nurse practitioners registered in the Corporate Provider Database between Jan. 1, 2000, and Dec. 31, 2010, were identified. We identified actively prescribing nurse practitioners through linkage of dispensed medications to people aged 65 years or older from the Ontario Drug Benefit database. For comparison, all prescription medications dispensed by family physicians to a similar group were identified. Geographic location was determined based on site of nurse practitioner practice. RESULTS: The number and proportion of actively prescribing nurse practitioners prescribing to older adults increased during the study period, from 44/340 (12.9%) to 888/1423 (62.4%). The number and proportion of medications dispensed for chronic conditions by nurse practitioners increased: in 2010, 9 of the 10 top medications dispensed were for chronic conditions. There was substantial variation in the proportion of nurse practitioners dispensing medication to older adults across provincial Local Health Integration Networks. INTERPRETATION: Prescribing by nurse practitioners to older adults, particularly of medications related to chronic conditions, increased between 2000 and 2010. The integration of nurse practitioners into primary care has not been consistent across the province and has not occurred in relation to population changes and perhaps population needs.

Identification, summary and comparison of tools used to measure organizational attributes associated with chronic disease management within primary care settings.

RATIONALE, AIMS AND OBJECTIVES: Given the increasing emphasis being placed on managing patients with chronic diseases within primary care, there is a need to better understand which primary care organizational attributes affect the quality of care that patients with chronic diseases receive. This study aimed to identify, summarize and compare data collection tools that describe and measure organizational attributes used within the primary care setting worldwide. METHODS: Systematic search and review methodology consisting of a comprehensive and exhaustive search that is based on a broad question to identify the best available evidence was employed. RESULTS: A total of 30 organizational attribute data collection tools that have been used within the primary care setting were identified. The tools varied with respect to overall focus and level of organizational detail captured, theoretical foundations, administration and completion methods, types of questions asked, and the extent to which psychometric property testing had been performed. The tools utilized within the Quality and Costs of Primary Care in Europe study and the Canadian Primary Health Care Practice-Based Surveys were the most recently developed tools. Furthermore, of the 30 tools reviewed, the Canadian Primary Health Care Practice-Based Surveys collected the most information on organizational attributes. CONCLUSIONS: There is a need to collect primary care organizational attribute information at a national level to better understand factors affecting the quality of chronic disease prevention and management across a given country. The data collection tools identified in this review can be used to establish data collection strategies to collect this important information.

Gender differences in the influence of social support on one-year changes in functional status in older patients with heart failure.

The purpose of this study was to determine the combined effects of gender and levels of social support on 1-year functional health outcomes in older persons diagnosed with heart failure (HF). Persons ≥ 65 years of age with an acute HF exacerbation (164 females; 271 males) were enrolled and followed for a year. Participants completed baseline and 12-month questionnaires containing clinical and demographic descriptive information and validated self-report measures of: (1) physical functioning (Medical Outcome Study [MOS] SF12 and Kansas City Cardiomyopathy Questionnaire [KCCQ]) and (2) social support (MOS- Social Support Survey). Women were more likely to be single, widowed or divorced, living alone and earning less annual income. At baseline, women reported significantly lower support and physical function scores. However, at 1 year there were no significant gender differences in the proportion of men or women who experienced clinically meaningful functional decline or death across the year of follow-up. In multivariable modeling, men with lower levels of social support were more likely to experience functional decline. This was not the case for women. Our findings suggest that gender-directed strategies to promote optimization of function for both men and women living with HF in their community are warranted.

The epidemiology of chronic pain in Canadian men and women between 1994 and 2007: longitudinal results of the National Population Health Survey.

BACKGROUND: The epidemiology of chronic pain is poorly understood due to a paucity of longitudinal studies limiting the ability to develop prevention strategies for a condition resistant to many current therapies. OBJECTIVES: To identify the incidence of and sociodemographic risk factors for chronic pain in Canadian women and men over a 12-year period. METHODS: Using data from the National Population Health Survey, individuals who developed chronic pain, defined as the presence of "usual pain" were identified. The cumulative incidence of chronic pain was calculated separately for men and women followed from 1994 to 2007. Biannual incidence and prevalence estimates of chronic pain were calculated during the same time period. Logistic regression analysis was used to examine predictors of chronic pain in men and women. RESULTS: The cumulative incidence over the 12-year period was 35.6% (women 39.0%; men 32.2%). Women had a higher biannual prevalence, but not incidence, of chronic pain compared with men. In women, being older, having lower education and being widowed, separated or divorced, increased the risk of chronic pain. There were no sociodemographic risk factors for chronic pain in men. CONCLUSION: Women had a higher prevalence - but not incidence - of chronic pain compared with men, indicative of longer duration of illness in women. Risk factors also differed according to sex, supporting current literature reporting potentially different mechanisms for men and women. A better understanding of risk factors is necessary to develop population-based preventive interventions. The former can only be achieved with population-based, longitudinal studies.

A cross-sectional study of breast cancer biomarkers among shift working nurses.

Objectives In 2007, the International Agency for Research on Cancer classified long-term shift work as a probable carcinogen, with the strongest evidence for breast cancer. One proposed mechanism involves night-time light exposure and decreases in melatonin, a circadian rhythmic hormone. It is hypothesised that melatonin influences patterns of sex hormone production that in turn influence breast cancer risk. This study sought to investigate the relationships of shift work history, 6-sulfatoxymelatonin (aMTs-6, the primary melatonin metabolite) and sex hormone levels among shift working nurses. Design This is a cross-sectional biomarker study. Setting 94 premenopausal nurses who work a full-time rotating shift schedule at one Ontario hospital were recruited for this study; 82 completed follow-up. Primary and secondary outcome measures Study participants provided morning void urine and fasting blood samples for the assessment of aMTs-6 and sex hormone (oestradiol, oestrone, progesterone, prolactin) levels, respectively. These data were collected at two time points (summer and winter) such that relationships between melatonin and sex hormones could be assessed with respect to two time frames of interest (acute and cross-seasonal). Results An inverse relationship between aMTs-6 and oestradiol was suggested in the winter (ß=-0.18, p=0.04), but this result was not statistically significant in multivariate modelling that adjusted for age, body mass index and menstrual cycle. Likewise, while oestradiol, oestrone and progesterone levels increased with greater years of shift work history (all p<0.05), these associations were attenuated after confounder adjustment. Conclusions These results do not support the proposed relationship between melatonin and sex hormone levels as biomarkers on the pathway of shift work and breast cancer but emphasise the importance of adjusting for confounders in modelling.

Back pain of working pregnant women: identification of associated occupational factors.

The objective of this study was to identify major occupational factors that were significantly correlated with back pain in pregnant women working in higher education, health care and service areas. A total of 73 working pregnant women were surveyed using questionnaires specifically designed for evaluating correlations between occupational factors and severity of back pain; 37 women were interviewed at both 20 and 34 weeks of pregnancy, 17 at 20 weeks only, and 19 were interviewed at 34 weeks only. "Rest breaks allowed" and "job autonomy" were negatively correlated with severity of back pain at 20 weeks of pregnancy. "Staying in a confined area" and "having restricted space" were positively correlated with severity of back pain at 34 weeks of pregnancy. The study suggests that allowing pregnant women to take more rest breaks and to have more job autonomy may reduce the severity of back pain during early pregnancy, and that allowing movement outside the working area and providing less restricted space may reduce back pain during late pregnancy.

Influences of body mass index and waist circumference on physical function in older persons with heart failure.

BACKGROUND: In older persons with heart failure (HF), body composition may influence physical function and treatment effectiveness. There is a lack of research concerning the associations between waist circumference (WC) or body mass index (BMI) and physical function in this population. OBJECTIVE: To determine whether BMI and WC are associated with physical function in older men and women with HF. METHODS: Seventy-one men and 36 women 65 years of age and older living with HF completed two surveys spaced three months apart. Height, weight, WC, time since diagnosis, edema, comorbidities and physical function were self-reported at baseline and follow-up. Physical function was determined using the physical component score of the Short Form-12 and the physical limitation domain (PLD) of the Kansas City Cardiomyopathy Questionnaire. Multivariate linear regression and analysis of covariance were used to evaluate the relationships between WC and BMI, as well as cross-classifications of WC and BMI with physical function, after adjusting for confounders and interactions. RESULTS: The cross-sectional and short-term follow-up analyses did not detect an association between WC or BMI and physical function, with the exception of changes in the PLD, which were significantly different across WC categories. Persons with a moderate WC experienced the greatest improvement in function. The physical component and PLD scores were lower than those reported by Canadians 75 years of age and older and stable HF patients, respectively. Women reported lower physical function scores than men. CONCLUSION: Findings from the present study indicate that older persons with HF, especially women, have poor physical functioning regardless of their WC or BMI.