Microbial characteristics in homes of asthmatic and non-asthmatic adults in the ECRHS cohort.

Microbial exposures in homes of asthmatic adults have been rarely investigated; specificities and implications for respiratory health are not well understood. The objectives of this study were to investigate associations of microbial levels with asthma status, asthma symptoms, bronchial hyperresponsiveness (BHR), and atopy. Mattress dust samples of 199 asthmatics and 198 control subjects from 7 European countries participating in the European Community Respiratory Health Survey II study were analyzed for fungal and bacterial cell wall components and individual taxa. We observed trends for protective associations of higher levels of mostly bacterial markers. Increased levels of muramic acid, a cell wall component predominant in Gram-positive bacteria, tended to be inversely associated with asthma (OR's for different quartiles: II 0.71 [0.39-1.30], III 0.44 [0.23-0.82], and IV 0.60 [0.31-1.18] P for trend .07) and with asthma score (P for trend .06) and with atopy (P for trend .02). These associations were more pronounced in northern Europe. This study among adults across Europe supports a potential protective effect of Gram-positive bacteria in mattress dust and points out that this may be more pronounced in areas where microbial exposure levels are generally lower.

The effects of growing up on a farm on adult lung function and allergic phenotypes: an international population-based study.

RATIONALE: Evidence has suggested that exposure to environmental or microbial biodiversity in early life may impact subsequent lung function and allergic disease risk. OBJECTIVES: To investigate the influence of childhood living environment and biodiversity indicators on atopy, asthma and lung function in adulthood. METHODS AND MEASUREMENTS: The European Community Respiratory Health Survey II investigated ∼10 201 participants aged 26-54 years from 14 countries, including participants' place of upbringing (farm, rural environment or inner city) before age 5 years. A 'biodiversity score' was created based on childhood exposure to cats, dogs, day care, bedroom sharing and older siblings. Associations with lung function, bronchial hyper-responsiveness (BHR), allergic sensitisation, asthma and rhinitis were analysed. MAIN RESULTS: As compared with a city upbringing, those with early-life farm exposure had less atopic sensitisation (adjusted OR 0.46, 95% CI 0.37 to 0.58), atopic BHR (0.54 (0.35 to 0.83)), atopic asthma (0.47 (0.28 to 0.81)) and atopic rhinitis (0.43 (0.32 to 0.57)), but not non-atopic outcomes. Less pronounced protective effects were observed for rural environment exposures. Women with a farm upbringing had higher FEV1 (adjusted difference 110 mL (64 to 157)), independent of sensitisation and asthma. In an inner city environment, a higher biodiversity score was related to less allergic sensitisation. CONCLUSIONS: This is the first study to report beneficial effects of growing up on a farm on adult FEV1. Our study confirmed the beneficial effects of early farm life on sensitisation, asthma and rhinitis, and found a similar association for BHR. In persons with an urban upbringing, a higher biodiversity score predicted less allergic sensitisation, but to a lesser magnitude than a childhood farm environment.

A rare missense mutation in CHRNA4 associates with smoking behavior and its consequences.

Using Icelandic whole-genome sequence data and an imputation approach we searched for rare sequence variants in CHRNA4 and tested them for association with nicotine dependence. We show that carriers of a rare missense variant (allele frequency=0.24%) within CHRNA4, encoding an R336C substitution, have greater risk of nicotine addiction than non-carriers as assessed by the Fagerstrom Test for Nicotine Dependence (P=1.2 × 10(-4)). The variant also confers risk of several serious smoking-related diseases previously shown to be associated with the D398N substitution in CHRNA5. We observed odds ratios (ORs) of 1.7-2.3 for lung cancer (LC; P=4.0 × 10(-4)), chronic obstructive pulmonary disease (COPD; P=9.3 × 10(-4)), peripheral artery disease (PAD; P=0.090) and abdominal aortic aneurysms (AAAs; P=0.12), and the variant associates strongly with the early-onset forms of LC (OR=4.49, P=2.2 × 10(-4)), COPD (OR=3.22, P=2.9 × 10(-4)), PAD (OR=3.47, P=9.2 × 10(-3)) and AAA (OR=6.44, P=6.3 × 10(-3)). Joint analysis of the four smoking-related diseases reveals significant association (P=6.8 × 10(-5)), particularly for early-onset cases (P=2.1 × 10(-7)). Our results are in agreement with functional studies showing that the human α4ß2 isoform of the channel containing R336C has less sensitivity for its agonists than the wild-type form following nicotine incubation.

Adhesion molecule increases in sleep apnea: beneficial effect of positive airway pressure and moderation by obesity.

BACKGROUND: Elevated levels of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) may contribute to cardiovascular disease and are associated with obstructive sleep apnea (OSA) and obesity. The relationship between OSA and obesity in determining ICAM-1 and VCAM-1 levels, and the effect of treatment, is unclear. OBJECTIVE: Our aim was to study whether positive airway pressure (PAP) usage resulted in changes in ICAM-1 and VCAM-1 after 2 years within 309 OSA patients from the Icelandic Sleep Apnea Cohort, and determine how obesity affected such changes. SUBJECTS/METHODS: The mean body mass index (BMI) was 32.4±5.1 kg m(-2); subjects had moderate-to-severe OSA (apnea-hypopnea index=45.0±20.2) and 79% were male. There were 177 full PAP users (⩾4 h per night and ⩾20 of last 28 nights), 44 partial (<4 h per night or <20 nights) and 88 nonusers. RESULTS: ICAM-1 (P<0.001) and VCAM-1 (P=0.012) change was significantly different among the PAP groups. The largest ICAM-1 differences were among the most obese subjects (P<0.001). At follow-up, nonusers had increased ICAM-1 compared with decreased levels in full users. All groups had increased VCAM-1, but nonusers had a significantly larger increase than full users. CONCLUSIONS: Within moderate-to-severe OSA patients, PAP usage prevents increases in adhesion molecules observed in nonusers after 2 years. For ICAM-1, the largest effect is in the most obese subjects. As OSA and obesity commonly coexist, the usage of PAP to limit increases in adhesion molecules may decrease the rate of progression of OSA-related cardiovascular disease.

Nocturnal GERD - a risk factor for rhinitis/rhinosinusitis: the RHINE study.

BACKGROUND: It has been suggested that gastroesophageal reflux disease (GERD) is a risk factor for developing rhinitis/rhinosinusitis, but data are lacking. This is a prospective 10-year follow-up study of a large multicenter cohort from Northern Europe, evaluating the relationship between nocturnal GERD and noninfectious rhinitis (NIR). METHODS: The study comprised 5417 subjects born between 1945 and 1973, who answered a questionnaire in 1999-2001 and again in 2010-2012. Noninfectious rhinitis was defined as having nasal obstruction, secretion, and/or sneezing without having the common cold. Odds ratios for developing NIR in relation to age, gender, BMI, smoking, asthma, and nocturnal GERD were calculated. RESULTS: During the 10-year observation period, 1034 subjects (19.1%) developed NIR. Subjects reporting nocturnal gastroesophageal reflux in both 1999 and 2010 had more NIR in 2010 (2.8% vs 1.2%, P < 0.001). There was a significant dose-response relationship between the number of reflux episodes/week in 1999 and the risk of having NIR in 2010, P = 0.02. In the multiple regression adjusted for age, gender, BMI, tobacco smoke, and asthma, those with nocturnal GERD in 1999 (≥3 episodes of nocturnal gastroesophageal reflux symptoms per week) had an OR of 1.6 (95% CI 1.0-2.5, P = 0.03) to develop NIR in 2010. Smoking was associated both with an increased risk of developing NIR (30.7% vs 24.0%, P < 0.001) and with the development of nocturnal GERD. CONCLUSION: This large, population-based, 10-year study indicates that nocturnal GERD was a risk factor for noninfectious rhinitis/rhinosinusitis. GERD should therefore be considered in patients with rhinitis of known and unknown origin.

Association between lung function and dyspnoea and its variation in the multinational Burden of Obstructive Lung Disease (BOLD) study.

BACKGROUND: Dyspnoea is a common symptom of respiratory disease. However, data on its prevalence in general populations and its association with lung function are limited and are mainly from high-income countries. The aims of this study were to estimate the prevalence of dyspnoea across several world regions, and to investigate the association of dyspnoea with lung function. METHODS: Dyspnoea was assessed, and lung function measured in 25,806 adult participants of the multinational Burden of Obstructive Lung Disease study. Dyspnoea was defined as ≥2 on the modified Medical Research Council (mMRC) dyspnoea scale. The prevalence of dyspnoea was estimated for each of the study sites and compared across countries and world regions. Multivariable logistic regression was used to assess the association of dyspnoea with lung function in each site. Results were then pooled using random-effects meta-analysis. RESULTS: The prevalence of dyspnoea varied widely across sites without a clear geographical pattern. The mean prevalence of dyspnoea was 13.7 % (SD=8.2 %), ranging from 0 % in Mysore (India) to 28.8 % in Nampicuan-Talugtug (Philippines). Dyspnoea was strongly associated with both spirometry restriction (FVC

The role of obesity, different fat compartments and sleep apnea severity in circulating leptin levels: the Icelandic Sleep Apnea Cohort study.

OBJECTIVES: To assess whether sleep apnea severity has an independent relationship with leptin levels in blood after adjusting for different measures of obesity and whether the relationship between obstructive sleep apnea (OSA) severity and leptin levels differs depending on obesity level. METHODS: Cross-sectional study of 452 untreated OSA patients (377 males and 75 females), in the Icelandic Sleep Apnea Cohort (ISAC), age 54.3±10.6 (mean±s.d.), body mass index (BMI) 32.7±5.3 kg m(-2) and apnea-hypopnea index 40.2±16.1 events per h. A sleep study and magnetic resonance imaging of abdominal visceral and subcutaneous fat volume were performed, as well as fasting serum morning leptin levels were measured. RESULTS: Leptin levels were more highly correlated with BMI, total abdominal and subcutaneous fat volume than visceral fat volume per se. No relationship was found between sleep apnea severity and leptin levels, assessed within three BMI groups (BMI <30, BMI 30-35 and BMI > or =35 kg m(-2)). In a multiple linear regression model, adjusted for gender, BMI explained 38.7% of the variance in leptin levels, gender explained 21.2% but OSA severity did not have a significant role and no interaction was found between OSA severity and BMI on leptin levels. However, hypertension had a significant effect on the interaction between OSA severity and obesity (P=0.04). In post-hoc analysis for nonhypertensive OSA subjects (n=249), the association between leptin levels and OSA severity explained a minor but significant variance (3.2%) in leptin levels. This relationship was greatest for nonobese nonhypertensive subjects (significant interaction with obesity level). No relationship of OSA severity and leptin levels was found for hypertensive subjects (n=199). CONCLUSION: Obesity and gender are the dominant determinants of leptin levels. OSA severity is not related to leptin levels except to a minor degree in nonhypertensive nonobese OSA subjects.

Onset of mucosal, dermal, and general symptoms in relation to biomarkers and exposures in the dwelling: a cohort study from 1992 to 2002.

UNLABELLED: We examined the associations between biomarkers of allergy and inflammation, indoor environment in dwellings, and incidence and remission of symptoms included in the sick building syndrome (SBS) and changes in the home environment of 452 adults who were followed from 1992 to 2002 within the Uppsala part of the European Community Respiratory Health Survey (ECRHS). The 10-year incidence (onset) of general, mucosal, and dermal symptoms was 8.5%, 12.7%, and 6.8%, respectively. Dampness or indoor molds at baseline was a predictor of incidence of general (relative risk [RR] = 1.98), mucosal (RR = 2.28), and dermal symptoms (RR = 1.91). Women had higher incidence of general (RR = 1.74) and mucosal symptoms (RR = 1.71). Indoor painting increased the incidence of general symptoms (RR = 1.62). Bronchial responsiveness (BR), eosinophil counts in blood, total IgE and eosinophilic cationic protein (ECP) in serum at baseline were predictors of incidence of SBS. At follow-up, BR, total IgE, and C-reactive protein (CRP ) were associated with increased incidence of SBS. Moreover, subjects with doctor-diagnosed asthma at baseline had a higher incidence of general (RR = 1.65) and mucosal symptoms (RR = 1.97). In conclusion, female gender, dampness or indoor molds, indoor painting, and biomarkers of allergy and inflammation were associated with a higher incidence of SBS symptoms, in particular mucosal symptoms. PRACTICAL IMPLICATIONS: The focus in Sweden on indoor environment issues over the last few decades has resulted in improvements in dwellings, and reduced tobacco smoking, which could be beneficial for public health. Reducing dampness and molds in the dwelling place is another important way of reducing occurrence of SBS symptoms in the general adult population. The association between the incidence of SBS symptoms and clinical biomarkers of allergy and inflammation suggests a common etiology between inflammatory diseases, including asthma, rhinitis, and SBS. Lastly, good agreement between self-reported and clinically diagnosed atopy indicates that questionnaire data on atopy can be used in epidemiological studies.

Risk factors of new-onset asthma in adults: a population-based international cohort study.

BACKGROUND: The occurrence of new-onset asthma during adulthood is common, but there is insufficient understanding of its determinants including the role of atopy. OBJECTIVE: To assess the risk factors for the development of new-onset asthma in middle-aged adults and to compare them according to atopy. METHODS: A longitudinal analysis of 9175 young adults who participated in two surveys of the European Community Respiratory Health Survey (ECRHS) conducted 9 years apart. FINDINGS: We observed 179 cases of new-onset asthma among 4588 participants who were free of asthma and reported at the beginning of the follow-up that they had never had asthma (4.5 per 1000 person-years). In a logistic regression, the following risk factors were found to increase the risk of new-onset asthma: female gender (OR: 1.97; 95% confidence interval (CI): 1.38, 2.81), bronchial hyperresponsiveness (3.25; 2.19, 4.83), atopy (1.55; 1.08, 2.21), FEV(1) < 100 % predicted (1.87; 1.34, 2.62), nasal allergy (1.98;1.39,2.84) and maternal asthma (1.91; 1.13; 3.21). Obesity, respiratory infections in early life and high-risk occupations increased the risk of new-onset asthma although we had limited power to confirm their role. Among the atopics, total IgE and sensitization to cat were independently related to the risk of new-onset asthma. The proportion of new-onset asthma attributable to atopy varied from 12% to 21%. CONCLUSION: Adults reporting that they had never had asthma were at a substantial risk of new-onset asthma as a result of multiple independent risk factors including lung function. Atopy explains a small proportion of new-onset adult asthma.

Present and future costs of COPD in Iceland and Norway: results from the BOLD study.

The Burden of Obstructive Lung Disease (BOLD) initiative provides standardised estimates of the burden of chronic obstructive pulmonary disease (COPD) worldwide. We estimate the current and future economic burden of COPD in Reykjavik, Iceland and Bergen, Norway using data from the BOLD initiative. Data on utilisation of healthcare resources were gathered from the BOLD survey, existing literature and unit costs from national sources. Economic data were applied to a Markov model using transition probabilities derived from Framingham data. Sensitivity analyses were conducted varying unit costs, utilisation and prevalence of disease. The cost of COPD was 478 euro per patient per yr in Iceland and 284 euro per patient per yr in Norway. The estimated cumulative costs of COPD for the population aged > or = 40 yrs, were 130 million euro and 1,539 million euro for the following 10 yrs in Iceland and Norway, respectively. Costs of COPD accounted for 1.2 and 0.7% of healthcare budgets in Iceland and Norway, respectively. Sensitivity analyses showed estimates were most sensitive to changes in exacerbation frequency. COPD has a significant economic burden in both Iceland and Norway and will grow in the future. Interventions aimed at avoiding exacerbations will have the most impact on costs of COPD over the next 20 yrs.

Underestimation of airflow obstruction among young adults using FEV1/FVC <70% as a fixed cut-off: a longitudinal evaluation of clinical and functional outcomes.

BACKGROUND: Early detection of airflow obstruction is particularly important among young adults because they are more likely to benefit from intervention. Using the forced expiratory volume in 1 s (FEV(1)) to forced vital capacity (FVC) (FEV(1)/FVC) <70% fixed ratio, airflow obstruction may be underdiagnosed. The lower limit of normal (LLN), which is statistically defined by the lower fifth percentile of a reference population, is physiologically appropriate but it still needs a clinical validation. METHODS: To evaluate the characteristics and longitudinal outcomes of subjects misidentified as normal by the fixed ratio with respect to the LLN, 6249 participants (aged 20-44 years) in the European Community Respiratory Health Survey were examined and divided into three groups (absence of airflow obstruction by the LLN and the fixed ratio; presence of airflow obstruction only by the LLN; presence of airflow obstruction by the two criteria) for 1991-1993. LLN equations were obtained from normal non-smoking participants. A set of clinical and functional outcomes was evaluated in 1999-2002. RESULTS: The misidentified subjects were 318 (5.1%); only 45.6% of the subjects with airflow obstruction by the LLN were also identified by the fixed cut-off. At baseline, FEV(1) (107%, 97%, 85%) progressively decreased and bronchial hyperresponsiveness (slope 7.84, 6.32, 5.57) progressively increased across the three groups. During follow-up, misidentified subjects had a significantly higher risk of developing chronic obstructive pulmonary disease and a significantly higher use of health resources (medicines, emergency department visits/hospital admissions) because of breathing problems than subjects without airflow obstruction (p<0.001). CONCLUSIONS: Our findings show the importance of using statistically derived spirometric criteria to identify airflow obstruction.

Optimum expression of adult lung function based on all-cause mortality: results from the Reykjavik study.

A variety of reference curves are used to derive predicted values for adult lung function, even within ethnically similar populations. Alternatives to percentage predicted value are sometimes used to allow for height in research. Strength of association with total mortality can be used to choose the optimal expression, between forced expiratory volume in 1s (FEV(1)) divided by height(2), FEV(1)/height(3), FEV(1)% predicted and difference from predicted. Data from the Reykjavik Study cohort, 1976-2002, included 5544 men and 8062 women randomly selected from the population. Total mortality was analysed by Cox proportional hazards regression in relation to each height-adjusted measure, allowing for age group, period of recruitment and body mass index, and smoking before or at baseline. FEV(1)/height(2) and FEV(1)/height(3) had stronger associations with mortality than FEV(1)% predicted and difference from predicted in men and in women. There were similar findings for forced vital capacity (FVC) in non-smokers and in women. FEV(1)/height(2) was slightly better predictive than FEV(1)/height(3) in men, but distributions of FEV(1)/height(3) in men and women were closer than those of FEV(1)/height(2). Clinical practise and epidemiological research would benefit from agreement on how to adjust lung function for height. Replication of these analyses in other cohort studies would inform the choice between FEV(1)/height(2) and FEV(1)/height(3).

Chronic bronchitis and urban air pollution in an international study.

OBJECTIVES: The chronic effects of urban air pollution are not well known. The authors' aim was to investigate the association between the prevalence and new onset of chronic bronchitis and urban air pollution. METHODS: Subjects from the general population randomly selected for the European Community Respiratory Health Survey (ECRHS I) during 1991-93 in 21 centres in 10 countries were followed up from the years 2000 to 2002 (n = 3232 males and 3592 females; average response rate = 65.3%). PM2.5 and elements, with the same equipment at centre level, and home outdoor NO2 in 1634 individuals were measured. Hierarchical models were used. RESULTS: The prevalence and new onset of chronic phlegm during follow up were 6.9% and 4.5%, respectively, 5.3% in males and 3.5% in females. Smoking, rhinitis, poor education, and low social class were associated with (prevalence and new onset of) chronic phlegm in both genders, and occupational exposures in males and traffic intensity (adjusted odds ratio for constant traffic, OR = 1.86; 95% CI 1.24 to 2.77) as well as home outdoor NO2 (OR > 50 microg/m3v < 20 microg3 = 2.71; 95% CI 1.03 to 7.16) among females. PM2.5 and S content at centre level did not show any association with prevalence or new onset of chronic phlegm. Similar results were obtained with chronic productive cough. CONCLUSION: Individual markers of traffic at household level such as reported intensity and outdoor NO2 were risk factors for chronic bronchitis among females.

Insomnia is more common among subjects living in damp buildings.

BACKGROUND: Insomnia is a condition with a high prevalence and a great impact on quality of life. Little is known about the relation between and sleep disturbances and the home environment. AIM: To analyse the association between insomnia and building dampness. METHODS: In a cross-sectional, multicentre, population study, 16 190 subjects (mean age 40 years, 53% women) were studied from Reykjavik in Iceland, Bergen in Norway, Umeå, Uppsala, and Göteborg in Sweden, Aarhus in Denmark, and Tartu in Estonia. Symptoms related to insomnia were assessed by questionnaire. RESULTS: Subjects living in houses with reported signs of building dampness (n = 2873) had a higher prevalence of insomnia (29.4 v 23.6%; crude odds ratio 1.35, 95% CI 1.23 to 1.48). The association between insomnia and different indicators of building dampness was strongest for floor dampness: "bubbles or discoloration on plastic floor covering or discoloration of parquet floor" (crude odds ratio 1.96, 95% CI 1.66 to 2.32). The associations remained significant after adjusting for possible confounders such as sex, age, smoking history, housing, body mass index, and respiratory diseases. There was no significant difference between the centres in the association between insomnia and building dampness. CONCLUSION: Insomnia is more common in subjects living in damp buildings. This indicates that avoiding dampness in building constructions and improving ventilation in homes may possibly have a positive effect on the quality of sleep.

Insomnia in men-a 10-year prospective population based study.

STUDY OBJECTIVES: to prospectively analyze changes in the prevalence of insomnia and the relationship between insomnia, aging, lifestyle, and medical disorders DESIGN: a longitudinal population survey. PARTICIPANTS: a randomly selected population sample of 2,602 men (age 30-69 years) from Uppsala in Sweden. INTERVENTION: all participants answered a questionnaire on sleep disturbances, lifestyle factors, and medical disorders in 1984 and again in 1994. MEASUREMENTS AND RESULTS: The prevalence of INSOMNIA was 10.3% in 1984 and 12.8% in 1994. No significant correlation was found between age and insomnia in any of the two time periods. Insomnia in 1994 was independently related to having insomnia in 1984 (OR=6.45), being over-weight (BMI> 27 kg/m2) (OR=1.35), physical inactivity (OR=1.42), alcohol dependence (OR=1.75), psychiatric disorders (OR=8.27) and joint/low back disorders (OR=2.95). The number of subject with reported insomnia in 1984 but not 1994 was 149. Subjects that quit smoking during the time period had an increased likeliness of remission (OR=2.70) while men who were overweight were less likely to remit (OR=0.43). CONCLUSIONS: We conclude that in men insomnia is related to lifestyle factors such as obesity, physical inactivity and alcohol dependency but not to aging. Medical disorders such as joint and low back disorders and psychiatric illnesses also increase the risk of reporting insomnia. This study demonstrates the close relationship between quality of sleep and overall health status.

Sleep disturbances in a young adult population: can gender differences be explained by differences in psychological status?

To study the prevalence of reported sleep disturbances and the association between these complaints and psychological status, 529 randomly selected subjects aged 20-45 years were questioned about their sleep symptoms and psychological status by means of questionnaires. In this young population, feeling refreshed in the morning almost every day was reported by only 15.3%. Females reported a significantly longer mean total sleep time (TST) than males (F: 425 +/- 58 minutes, M: 403 +/- 50 minutes; p < 0.01). Despite this, the difference compared with the reported need of sleep was greater in females (56 +/- 62 minutes) than in males (40 +/- 51 minutes) (p < 0.05). Difficulties maintaining sleep (DMS, > or = 3/week) (F: 20.1%, M: 10.4%; p < 0.01), the absence of feeling refreshed in the morning (F: 36.2%, M: 26.8%; p < 0.05), and excessive daytime sleepiness (EDS) (F: 23.3%, M: 15.9%; p < 0.05) were significantly more common among females. According to the Hospital Anxiety and Depression scale, females suffered from anxiety more frequently than males (F: 32.8%, M: 18.9%; p < 0.001). An association was found between anxiety and many sleep disturbances. After making adjustments for age, smoking, snoring, gender and psychological status by means of multiple regression, the gender differences mentioned above remained significant. We conclude that despite a longer TST, females report insufficient sleep, EDS, DMS, and the absence of feeling refreshed in the morning more frequently than males. The higher prevalence of anxiety among females alone cannot explain the gender differences in sleep disturbances seen in this population.

Prevalence of sleep disturbances among young adults in three European countries.

The aim of this investigation was to study the geographic variation in sleep complaints and to identify risk factors for sleep disturbances in three European countries: Iceland (Reykjavik), Sweden (Uppsala and Göteborg) and Belgium (Antwerp). The study involved a random population of 2,202 subjects (age 20-45 years) who participated in the European Community Respiratory Health Survey. The subjects answered a questionnaire on sleep disturbances. Participants in Iceland and Sweden also estimated their sleep habits and sleep times during a period of 1 week in a sleep diary. Habitual (> or = 3/week) difficulties inducing sleep (DIS) were reported by 6-9% and early morning awakenings by 5-6% of the subjects. The estimated number of awakenings and the prevalence of nightmares was significantly lower in Reykjavik. Participants in Reykjavik went to bed at night and woke in the morning approximately 1 hour later than participants at the Swedish centers (p < 0.001). Symptoms of gastroesophageal reflux (GER) were associated with DIS (odds ratio [OR] = 2.7), nightmares (OR = 4.4), longer sleep latency and frequent nocturnal awakenings. Smoking correlated positively to DIS (OR = 1.8) and estimated sleep latency. We conclude that the prevalence of DIS was fairly similar at these four European centers but that there was a variation in the prevalence of nightmares and nocturnal awakenings. The significant correlation between reported GER and subjective quality of sleep should be followed up in studies using objective measurements.

Epidemiology of sleep-related obstructive breathing.

The diagnosis of obstructive sleep apnoea syndrome (OSAS) and upper airway resistance syndrome (UARS) is based both on a combination of laboratory findings from whole-night sleep recordings and daytime symptoms. Due to the recent interest in breathing disturbances during sleep many prevalence studies have been performed within this field. There are, however, methodological difficulties in characterizing these syndromes in large populations; many of the studies have therefore been unable to present an overview of the complete syndromes but rather have focused on specific characteristics. In epidemiological research snoring and/or daytime sleepiness have often been used as markers of OSAS, while other studies have looked only on the respiratory disturbances or oxygen desaturation. Studies on the prevalence of OSAS based on polysomnography are reviewed here, as well as investigations where associated factors such as cardiovascular diseases and mortality were analysed. The interrelationships between snoring, daytime symptoms and laboratory findings are discussed. Gender, age, obesity, smoking, alcohol and ethnicity are all factors that influence the prevalence of OSAS. The data on associations between OSAS and cardiovascular disease or mortality are sometimes unrelated. Much of the discrepancy between different studies can be explained by the methodological difficulties connected with the definition of OSAS and also by the fact that the association between sleep-disordered breathing and cardiovascular outcome seems to be age-dependent.

Prevalence of sleep apnea syndrome among Swedish men--an epidemiological study.

The prevalence of the sleep apnea syndrome (SAS) among Swedish men 30-69 years old was estimated by a two-stage procedure. In the first stage, 4064 questionnaires were mailed to a random sample of a defined population in the municipality of Uppsala. The response rate was almost 80%; 15.6% of the responders were habitual snorers and 5.8% complained of daytime sleepiness. From these, a group of 166 men highly suspected of having SAS was selected. Eventually, 61 of these came for all-night polysomnographic studies, and 15 of these were found to have SAS. On this basis the lower limit of the prevalence of SAS was estimated to be as high as 1.3%. The majority of subjects with the syndrome were in the age group 50-59 years.

Chest physiotherapy. Evaluation by transcutaneous blood gas monitoring.

Two respiratory physiotherapy methods were evaluated by analyzing changes in the transcutaneous partial pressure of CO2 (tcPCO2) in 15 patients with respiratory insufficiency. All were receiving continuous oxygen therapy and had CO2 retention. The physiotherapy methods compared were thoracic compression (TC) and positive expiratory pressure (PEP). The mean decrease (+/- SD) in tcPCO2 was the same with both methods, 0.6 +/- 0.4 kPa, but there were interindividual differences. This study indicates that both TC and PEP effectively decrease tcPCO2, although only temporarily in many cases. Continuous tcPCO2 monitoring is a useful clinical method for determining and teaching optimal respiratory therapy.