Alice Jessie Clark

Symptoms of sleep disordered breathing and risk of cancer: a prospective cohort study.

STUDY OBJECTIVES Sleep disordered breathing (SDB) has been associated with oxidative stress, inflammation, and altered hormonal levels, all of which could affect the risk of cancer. The aim of the study is to examine if symptoms of SDB including snoring, breathing cessations, and daytime sleepiness affect the incidence of total cancer and subtypes of cancer. DESIGN Prospective cohort study. SETTING The third wave (1991-1993) of the Copenhagen City Heart Study. PARTICIPANTS There were 8,783 men and women in whom cancer had not been previously diagnosed. MEASUREMENTS AND RESULTS Participants answered questions about snoring and breathing cessations in 1991-1993, whereas information about daytime sleepiness based on the Epworth Sleepiness Scale was collected in a subset of the participants (n = 5,894) in 1998. First-time incidence of cancer was followed until December 2009 in a nationwide cancer register. We found no overall association between symptoms of SDB and incident cancer. Yet, in the small group with high daytime sleepiness, we observed a surprisingly higher cancer incidence (hazard ratio = 4.09; 95% CI 1.58-10.55) in persons younger than 50 years. We also found a higher risk of virus/immune-related cancers (2.73; 1.27-5.91) and alcohol-related cancers (4.92; 1.45-16.76) among persons with daytime sleepiness. More SDB symptoms were associated with a higher risk of smoking-related cancers (Ptrend: 0.04). Apart from these findings there were no clear associations between symptoms of sleep disordered breathing and cancer subtypes. CONCLUSION We found very limited evidence of relationship between symptoms of sleep disordered breathing and incidence of cancer.

The effect of sleep disordered breathing on the outcome of stroke and transient ischemic attack: a systematic review.

STUDY OBJECTIVES The primary objective was to systematically review the literature on how sleep disordered breathing (SDB) affects recurrence and death among stroke or transient ischemic attack (TIA) patients. A secondary objective was to evaluate how treatment of SDB with continuous positive airway pressure (CPAP) affects the risk of recurrence and death in these patients. METHODS Adults (18+) with a stroke or TIA diagnosis were eligible for inclusion. Case groups consisted of patients with a sleep disorder. The outcomes of interest were all-cause mortality, recurrent vascular events, and case fatality. RESULTS Ten articles covering 1,203 stroke and TIA patients were included in the review. The results generally support a dose-response relationship between severity of SDB and risk of recurrent events and all-cause mortality in stroke and TIA patients. Three small-scale articles with substantial risk of bias evaluated the effects of CPAP therapy, and the results are inconclusive. Data on case fatality is too sparse to be conclusive. CONCLUSIONS Existing studies provide sufficient data to establish obstructive SDB as a negative predictor of all-cause mortality and recurrent vascular events following stroke or TIA. The ability of CPAP treatment to lower the risk of serious adverse outcomes after stroke remains controversial because of substantial risk of bias identified in most of the eligible studies addressing this relation. Additional studies are needed.

Sleep Impairment and Prognosis of Acute Myocardial Infarction: A Prospective Cohort Study

STUDY OBJECTIVES Impaired sleep is an established risk factor for the development of cardiovascular disease, whereas less is known about how impaired sleep affects cardiovascular prognosis. The aim of this study is to determine how different aspects of impaired sleep affect the risk of case fatality and subsequent cardiovascular events following first-time acute myocardial infarction (AMI). DESIGN Prospective cohort study. SETTING The Stockholm Heart Epidemiology Program, Sweden. PARTICIPANTS There were 2,246 first-time AMI cases. MEASUREMENTS AND RESULTS Sleep impairment was assessed by the Karolinska Sleep Questionnaire, which covers various indices of impaired sleep: disturbed sleep, impaired awakening, daytime sleepiness, and nightmares. Case fatality, defined as death within 28 days of initial AMI, and new cardiovascular events within up to 10 y of follow-up were identified through national registries. In women, disturbed sleep showed a consistently higher risk of long-term cardiovascular events: AMI (hazard ratio [HR] = 1.69; 95% confidence interval [CI] 0.95-3.00), stroke (HR = 2.61; 95% CI: 1.19-5.76), and heart failure (HR = 2.43; 95% CI: 1.18-4.97), whereas no clear effect of impaired sleep on case fatality was found in women. In men, a strong effect on case fatality (odds ratio = 3.27; 95% CI: 1.76-6.06) was observed in regard to impaired awakening; however, no consistent effect of impaired sleep was seen on long-term cardiovascular prognosis. CONCLUSION Results suggest sex-specific effects of impaired sleep that differ by short- and long-term prognosis. Sleep complaints are frequent, easily recognizable, and potentially manageable. Evaluation of sleep complaints may, even if they represent prognostic markers rather than risk factors, provide additional information in clinical risk assessment that could benefit secondary cardiovascular prevention.

Psychosocial risk factors, pre-motor symptoms and first-time hospitalization with Parkinson's disease: a prospective cohort study.

Experimental studies support a link between stress and development of parkinsonian symptoms, but prospective population studies are lacking. The aim of the current study is to determine the effects of several psychosocial factors on the risk of Parkinsons disease (PD), as well as to identify potential pre‐motor symptoms for PD in a large prospective cohort study.

Onset of impaired sleep as a predictor of change in health-related behaviours; analysing observational data as a series of non-randomized pseudo-trials

BACKGROUND Changes in health-related behaviour may be a key mechanism linking impaired sleep to poor health, but evidence on this is limited. In this study, we analysed observational data to determine whether onset of impaired sleep is followed by changes in health-related behaviours. METHODS We used data from 37,508 adults from the longitudinal Finnish Public Sector Study. In analysis of 59 152 person-observations on duration and quality of sleep and health-related behaviours (alcohol consumption, smoking, physical activity and weight control), data were treated as a series of non-randomized pseudo-trials with strict predefined criteria for data inclusion and temporality. RESULTS Smokers who experienced onset of short sleep were less likely to quit smoking than those with persistent normal sleep [odds ratio (OR) = 0.78, 95% confidence interval (CI): 0.64-0.97]. Onset of short sleep also predicted initiating high-risk alcohol consumption (OR = 1.17, 95% CI: 1.00-1.37). Onset of disturbed sleep was associated with changes in all assessed health-related behaviours: initiation of high-risk alcohol consumption (OR = 1.23, 95% CI: 1.05-1.45), quitting smoking (OR = 0.80, 95% CI: 0.63-1.00), becoming physically inactive (OR = 1.17, 95% CI: 1.06-1.30) and becoming overweight or obese (OR = 1.12, 95% CI: 1.01-1.23). CONCLUSIONS Findings suggest that the onset of short or disturbed sleep are risk factors for adverse changes in health-related behaviours. These findings highlight potential pathways linking impaired sleep to the development of lifestyle-related morbidity and mortality.

Impaired sleep and allostatic load: cross-sectional results from the Danish Copenhagen Aging and Midlife Biobank.

OBJECTIVE Understanding the mechanisms linking sleep impairment to morbidity and mortality is important for future prevention, but these mechanisms are far from elucidated. We aimed to determine the relation between impaired sleep, both in terms of duration and disturbed sleep, and allostatic load (AL), which is a measure of systemic wear and tear of multiple body systems, as well as with individual risk markers within the cardiac, metabolic, anthropometric, and immune system. METHODS A cross-sectional population-based study of 5226 men and women from the Danish Copenhagen Aging and Midlife Biobank with comprehensive information on sleep duration, disturbed sleep, objective measures of an extensive range of biological risk markers, and physical conditions. RESULTS Long sleep (mean difference 0.23; 95% confidence interval, 0.13, 0.32) and disturbed sleep (0.14; 0.06, 0.22) were associated with higher AL as well as with high-risk levels of risk markers from the anthropometric, metabolic, and immune system. Sub-analyses suggested that the association between disturbed sleep and AL might be explained by underlying disorders. Whereas there was no association between short sleep and AL, the combination of short and disturbed sleep was associated with higher AL (0.19; 0.08, 0.30) and high-risk levels of immune system markers. CONCLUSION Our study suggests small but significant differences in the distribution of allostatic load, a pre-clinical indicator of disease risk and premature death, for people with impaired relative to normal sleep. Impaired sleep may be a risk factor for developing disease and be a risk marker for underlying illness or sleep disorders.

Onset of Impaired Sleep and Cardiovascular Disease Risk Factors: A Longitudinal Study.

STUDY OBJECTIVES Impaired sleep has been linked to increased risk of cardiovascular disease (CVD), but the underlying mechanisms are still unsettled. We sought to determine how onset of impaired sleep affects the risk of established physiological CVD risk factors (i.e., hypertension, diabetes, and dyslipidemia). METHODS In a longitudinal cohort study with 3 survey waves (2000, 2004, 2008) from the Finnish Public Sector study we used repeated information on sleep duration and disturbances to determine onset of impaired sleep. Information on development of CVD risk factors, as indicated by initiation of medication for hypertension, diabetes, and dyslipidemia was derived from electronic medical records within 8 years of follow-up. Data on 45,647 participants was structured as two data-cycles to examine the effect of change in sleep (between two waves) on incident CVD events. We applied strict inclusion and exclusion criteria to determine temporality between changes in sleep and the outcomes. RESULTS While we did not find consistent effects of onset of short or long sleep, we found onset of disturbed sleep to predict subsequent risk of hypertension (hazard ratio = 1.22, 95% CI: 1.04-1.44) and dyslipidemia (HR = 1.17, 95% CI: 1.07-1.29) in fully adjusted analyses. CONCLUSIONS Results suggest that onset of sleep disturbances rather than short or long sleep mark an increase in physiological risk factors, which may partly explain the higher risk of CVD observed among impaired sleepers. COMMENTARY A commentary on this paper appears in this issue on page 1629.

Psychosocial risk factors for the metabolic syndrome: A prospective cohort study

BACKGROUND/OBJECTIVES Metabolic deregulations and development of metabolic syndrome may be an important pathway underlying the relationship between stress and cardiovascular disease. We aim to estimate the effect of a comprehensive range of psychosocial factors on the risk of developing metabolic syndrome in men and women. METHODS The study population consisted of 3621 men and women from the Copenhagen City Heart Study who were free of metabolic syndrome at baseline and reexamined after 10years. The data was analyzed by multivariable logistic regression models adjusted for age, education, income, menopausal status and life style factors. RESULTS We found major life events in adult life (OR 1.48, 95% CI 0.93 to 2.36) and major life events at work (OR 2.75, 95% CI 1.38 to 5.50), lacking a confidant (OR 1.94, 95% CI 1.07 to 3.53) and dissatisfaction with social network (OR 1.53, 95% CI 1.11 to 2.11) to be risk factors for developing the metabolic syndrome in women, while vital exhaustion (OR 2.09, 95% CI 0.95 to 4.59) and intake of sleep medications (OR 2.54, 95% CI 0.92 to 5.96) may play a more important role in men. CONCLUSIONS Experiencing major life events in work and adult life and/or dysfunctional social networks is a risk factor for metabolic syndrome in women, and stress reactions such as vital exhaustion and intake of sleep medications may play a more important role in the development of metabolic syndrome men.

Psychosocial Risk Factors for Hospitalisation and Death from Chronic Obstructive Pulmonary Disease: A Prospective Cohort Study

Abstract Only a few smaller studies have addressed the effect of psychosocial factors on risk of chronic obstructive pulmonary disease (COPD) in spite of the potential for psychosocial stress to affect development of the disease through immunological and behavioural pathways. The aim of this study is to determine the relation between various psychosocial risk factors, individually and accumulated, and COPD hospitalisation and deaths. A total of 8728 women and men free of asthma and COPD participating in the Copenhagen City Heart Study, were asked comprehensive questions on major life events, work-related stress, social network, vital exhaustion, economic hardship, and sleep medication in 1991–1993 and followed in nationwide registers until 2009, with <2% loss to follow-up. During follow-up, 461 women and 352 men were hospitalized with or died from COPD. Major life events in adult life and vital exhaustion were both associated with a higher risk of COPD in an exposure-dependent manner, with high vital exhaustion being associated with a hazard ratio [HR] of 2.31 (95% CI 1.69–3.16) for women and 2.48 (1.69–3.64) for men. A higher risk of COPD was also found in participants who experienced economic hardship or had a dysfunctional social network. Furthermore, the accumulation of psychosocial risk factors was associated with a higher risk of COPD in both women (HR = 2.40, 1.78–3.22) and men (HR = 1.93, 1.33–2.80). Psychosocial vulnerability may be important to consider both in clinical practice and when planning future preventive strategies against COPD.

Sleep Duration and Sleep Disturbances as Predictors of Healthy and Chronic Disease-Free Life Expectancy between Ages 50 and 75: A Pooled Analysis of Three Cohorts

Background The aim of this study was to examine the associations of sleep duration and sleep disturbances with healthy and chronic disease-free life expectancy (LE) between ages 50 and 75. Methods Data were drawn from repeated waves of three occupational cohort studies in England, Finland, and Sweden (n = 55,494) and the follow-up ranged from 6 to 18 years. Self-reported sleep duration was categorized into <7, 7-8.5, and ≥9 hours and sleep disturbances into no, moderate, and severe. Health expectancy was estimated with two health indicators: healthy LE based on years in good self-rated health and chronic disease-free LE based on years without chronic diseases. Multistate life table models were used to estimate healthy and chronic disease-free LE from age 50 to 75 years for each category of sleep measures in each cohort. Fixed-effects meta-analysis was used to pool the cohort-specific results into summary estimates. Results Persons who slept 7-8.5 hours could expect to live 19.1 (95% CI 19.0-19.3) years in good health and 13.5 (95% CI 13.2-13.7) years without chronic diseases between ages 50 and 75. Healthy and disease-free years were 1-3 years shorter for those who slept less than 7 hours or slept 9 hours or more. Persons who did not have sleep disturbances could expect to live 20.4 (95% CI 20.3-20.6) years in good health and 14.3 (95% CI 14.1-14.5) years without chronic diseases between ages 50 and 75. Healthy and disease-free years were 6-3 years shorter for those who reported severe sleep disturbances. Conclusions Sleeping 7-8.5 hours and having no sleep disturbances between ages 50 to 75 are associated with longer healthy and chronic disease-free LE.