Impact of the metabolic syndrome on cardiopulmonary morbidity and mortality in individuals with lung function impairment: a prospective cohort study of the Danish general population

Background

Whether the metabolic syndrome plays a role for the prognosis of individuals with lung function impairment (preserved ratio impaired spirometry (PRISm) or airflow limitation) is unclear. We hypothesised that the metabolic syndrome in individuals with lung function impairment is associated with increased cardiopulmonary morbidity and mortality.

Methods

The Copenhagen General Population Study was initiated in 2003 based on a random sample of white men and women aged 20-100 years drawn from the Danish general population. The risk of ischemic heart disease/heart failure, respiratory disease, and all-cause mortality was analysed with Cox models adjusted for age, sex, current smoking, and asthma during 15 years of follow-up.

Findings

Among 106,845 adults, 86,159 had normal lung function, 6126 had PRISm, and 14,560 had airflow limitation. We observed 10,448 hospital admissions for ischemic heart disease/heart failure, 21,140 for respiratory disease, and 11,125 deaths. Individuals with versus individuals without the metabolic syndrome generally had higher 5-year absolute risk of all outcomes, including within those with normal lung function, mild-moderate-severe PRISm, and very mild-mild-moderate-severe airflow limitation alike. Compared to individuals without the metabolic syndrome and with normal lung function, those with both the metabolic syndrome and severe PRISm had hazard ratios of 3.74 (95% CI: 2.53-5.55; p < 0.0001) for ischemic heart disease/heart failure, 5.02 (3.85-6.55; p < 0.0001) for respiratory disease, and 5.32 (3.76-7.54; p < 0.0001) for all-cause mortality. Corresponding hazard ratios in those with both the metabolic syndrome and severe airflow limitation were 2.89 (2.34-3.58; p < 0.0001) for ischemic heart disease/heart failure, 5.98 (5.28-6.78; p < 0.0001) for respiratory disease, and 4.16 (3.50-4.95; p < 0.0001) for all-cause mortality, respectively. The metabolic syndrome explained 13% and 27% of the influence of PRISm or airflow limitation on ischemic heart disease/heart failure and all-cause mortality.

Interpretation

The metabolic syndrome conferred increased risk of cardiopulmonary morbidity and mortality at all levels of lung function impairment.

Funding

Danish Lung Foundation, Danish Heart Foundation, Capital Region of Copenhagen, and Boehringer Ingelheim. JV is supported by the NIHR Manchester BRC.

Complications and discomfort after research bronchoscopy in the MicroCOPD study

Background

Data on discomfort and complications from research bronchoscopy in chronic obstructive pulmonary disease (COPD) and asthma is limited. We present complications and discomfort occurring within a week after bronchoscopy, and investigate personal and procedural risk factors.

Methods

239 subjects with COPD, asthma or without lung disease underwent research bronchoscopies as part of a microbiome study of the lower airways (the MicroCOPD study). Bronchoscopy was done in the supine position with oral scope insertion with the option of light conscious alfentanil sedation. Sampling consisted of protected specimen brushes, bronchoalveolar lavage, small volume lavage and for some, endobronchial biopsies. Bleeding, desaturation, cough, haemodynamic changes, dyspnoea and other events that required an unplanned intervention or early termination of bronchoscopy were prospectively recorded. Follow-up consisted of a telephone interview where subjects rated discomfort and answered questions about fever sensation and respiratory symptoms in the week following bronchoscopy.

Results

An unplanned intervention or early termination of bronchoscopy was required in 25.9% of bronchoscopies. Three subjects (1.3%) experienced potentially severe complications, of which all recovered without sequelae. COPD subjects experienced more dyspnoea than controls. Sedation and lower age was associated with less unplanned intervention or premature termination. About half of the subjects (47.7%) reported fever. Discomfort was associated with postprocedural fever, dread of bronchoscopy, higher score on the COPD Assessment Test and never-smoking. In subjects undergoing more than one bronchoscopy, the first bronchoscopy was often predictive for complications and postprocedural fever in the repeated bronchoscopy.

Conclusion

Research bronchoscopies were not associated with more complications or discomfort in COPD subjects. 47.7% experienced postbronchoscopy fever sensation, which was associated with discomfort.

The airway microbiota and exacerbations of COPD

Aim

The aim of this study was to investigate whether the compositionality of the lower airway microbiota predicts later exacerbation risk in persons with COPD in a cohort study.

Materials and methods

We collected lower airways microbiota samples by bronchoalveolar lavage and protected specimen brushes, and oral wash samples from 122 participants with COPD. Bacterial DNA was extracted from all samples, before we sequenced the V3-V4 region of the 16S RNA gene. The frequency of moderate and severe COPD exacerbations was surveyed in telephone interviews and in a follow-up visit. Compositional taxonomy and α and β diversity were compared between participants with and without later exacerbations.

Results

The four most abundant phyla were Firmicutes, Bacteroidetes, Proteobacteria and Fusobacteria in both groups, and the four most abundant genera were Streptococcus, Veillonella, Prevotella and Gemella. The relative abundances of different taxa showed a large variation between samples and individuals, and no statistically significant difference of either compositional taxonomy, or α or β diversity could be found between participants with and without COPD exacerbations within follow-up.

Conclusion

The findings from the current study indicate that individual differences in the lower airway microbiota in persons with COPD far outweigh group differences between frequent and nonfrequent COPD exacerbators, and that the compositionality of the microbiota is so complex as to present large challenges for use as a biomarker of later exacerbations.

Contrary to previous reports, in this study there were no significant associations between the lung microbiota in stable COPD and COPD exacerbation frequencyhttps://bit.ly/2ZVcNdG

Risk factors for lung cancer in COPD - results from the Bergen COPD cohort study

BACKGROUND

COPD patients have an increased risk of developing lung cancer, but the underlying mechanisms are poorly understood. We aimed to identify risk factors for lung cancer in patients from the Bergen COPD Cohort Study.

METHODS

We compared 433 COPD patients with 279 healthy controls, all former or current smokers. All COPD patients had FEV1<80% and FEV1/FVC-ratio<0.7. Baseline predictors were sex, age, spirometry, body composition, smoking history, emphysema assessed by CT, chronic bronchitis, prior exacerbation frequency, Charlson Comorbidity Score, inhalation medication and 44 serum/plasma inflammatory biomarkers. Patients were followed up for 9 years recording incidence of lung cancer. Cox-regression models were fitted for the statistical analyses. The biomarkers were evaluated using principal component analysis.

RESULTS

28 COPD patients and 3 controls developed lung cancer, COPD patients had a significantly higher risk of developing lung cancer, (HR 5.0; 95% CI 1.5-17.1, p < 0.01, adjusted values). Among COPD patients, emphysema (HR 4.4; 1.7-10.8, p < 0.01) and obesity (HR 3.3; 1.3-8.5, p = 0.02) were associated with a higher cancer rate. Use of inhaled steroids was associated with a lower rate (HR 0.4; 0.2-0.9, p = 0.03). Smoking status, pack-years smoked or levels of systemic inflammatory markers, except for interferon gamma-induced protein 10, did not affect the lung cancer rate in patients with COPD.

CONCLUSION

Patients with COPD have a higher lung cancer rate compared to healthy controls adjusted for smoking. The presence of emphysema and obesity in COPD predicted a higher lung cancer risk in COPD patients. Systemic inflammation was not associated with increased lung cancer risk.

Complications and discomfort of bronchoscopy: a systematic review

Objective

To identify bronchoscopy-related complications and discomfort, meaningful complication rates, and predictors.

Method

We conducted a systematic literature search in PubMed on 8 February 2016, using a search strategy including the PICO model, on complications and discomfort related to bronchoscopy and related sampling techniques.

Results

The search yielded 1,707 hits, of which 45 publications were eligible for full review. Rates of mortality and severe complications were low. Other complications, for instance, hypoxaemia, bleeding, pneumothorax, and fever, were usually not related to patient characteristics or aspects of the procedure, and complication rates showed considerable ranges. Measures of patient discomfort differed considerably, and results were difficult to compare between different study populations.

Conclusion

More research on safety aspects of bronchoscopy is needed to conclude on complication rates and patient- and procedure-related predictors of complications and discomfort.

Diffusion capacity and CT measures of emphysema and airway wall thickness - relation to arterial oxygen tension in COPD patients

BACKGROUND

Decreased diffusing capacity of the lung for carbon monoxide (DLCO) is associated with emphysema. DLCO is also related to decreased arterial oxygen tension (PaO2), but there are limited data on associations between PaO2 and computed tomography (CT) derived measures of emphysema and airway wall thickness.

OBJECTIVE

To examine whether CT measures of emphysema and airway wall thickness are associated with level of arterial oxygen tension beyond that provided by measurements of diffusion capacity and spirometry.

METHODS

The study sample consisted of 271 smoking or ex-smoking COPD patients from the Bergen COPD Cohort Study examined in 2007-2008. Emphysema was assessed as percent of low-attenuation areas<-950 Hounsfield units (%LAA), and airway wall thickness as standardised measure at an internal perimeter of 10 mm (AWT-Pi10). Multiple linear regression models were fitted with PaO2 as the outcome variable, and %LAA, AWT-Pi10, DLCO and carbon monoxide transfer coefficient (KCO) as main explanatory variables. The models were adjusted for sex, age, smoking status, and haemoglobin concentration, as well as forced expiratory volume in one second (FEV1).

RESULTS

Sixty two per cent of the subjects were men, mean (SD) age was 64 (7) years, mean (SD) FEV1 in percent predicted was 50 (15)%, and mean PaO2 (SD) was 9.3 (1.1) kPa. The adjusted regression coefficient (CI) for PaO2 was -0.32 (-0.04-(-0.019)) per 10% increase in %LAA (p<0.01). When diffusion capacity and FEV1 were added to the model, respectively, the association lost its statistical significance. No relationship between airway wall thickness and PaO2 was found.

CONCLUSION

CT assessment of airway wall thickness is not associated with arterial oxygen tension in COPD patients. Emphysema score measured by chest CT, is related to decreased PaO2, but cannot replace measurements of diffusion capacity in the clinical evaluation of hypoxaemia.

Self-reported influenza vaccination and protective serum antibody titers in a cohort of COPD patients

BACKGROUND

COPD patients are advised vaccination against seasonal influenza, yet few studies have evaluated the protective antibody titers obtained in this patient group.

AIMS

1) To describe protective titers in COPD patients who self-reported influenza vaccination compared with vaccinated subjects without COPD and unvaccinated COPD patients, 2) analyze whether clinical parameters predicted influenza-specific antibody titers, and 3) whether antibody titers to influenza A at baseline could predict exacerbation risk or 5 years all-cause mortality.

METHODS

Influenza A (H1N1 and H3N2) titers were measured by haemagglutination inhibition assay in serum from 432 COPD patients and 77 controls in the Bergen COPD Cohort Study, at yearly visits between 2006/09. Titers of 40 or above were considered protective. We examined the variables sex, age, body composition, smoking, GOLD stage, yearly exacerbations, inhaled steroids, and Charlson score as predictive of titers, both univariately and in a multivariable model estimated by generalized estimating equations. The exacerbation incidence rate ratios and mortality hazard ratios were assessed by negative binominal and cox regression models respectively.

RESULTS

At baseline, 59% of COPD patients reported influenza vaccination during the last season. Levels of predictive titers varied considerably each season, but trended lower in COPD patients compared with controls. Neither sex, age, body composition, smoking, comorbidities, GOLD stage nor use of inhaled steroids consistently predicted titers. Having high titers at baseline did not impact later risk for exacerbations, but seemed to be associated with higher all-cause mortality, even after adjustment for COPD disease characteristics.

CONCLUSION

Vaccination coverage for influenza is imperfect for COPD patients in Norway, and there is a concern that immunization is suboptimal.

Oxygen desaturation in 6-min walk test is a risk factor for adverse outcomes in COPD

The 6-min walk test (6MWT) is an exercise test that measures functional status in chronic obstructive pulmonary disease (COPD) patients and provides information on oxygen desaturation. We investigated oxygen desaturation during 6MWT as a risk factor for important COPD outcomes: mortality, frequency of exacerbations, decline in lung function and decline in lean body mass.433 COPD patients were included in the Bergen COPD Cohort Study 2006-2009, and followed-up for 3 years. Patients were characterised using spirometry, bioelectrical impedance measurements, Charlson comorbidity score, exacerbation history, smoking and arterial blood gases. 370 patients completed the 6MWT at the baseline of the study. Information on all-cause mortality was collected in 2011.Patients who experienced oxygen desaturation during the 6MWT had an approximately twofold increased risk of death (hazard ratio 2.4, 95% CI 1.2-5.1), a 50% increased risk for experiencing later COPD exacerbations (incidence rate ratio 1.6, 95% CI 1.1-2.2), double the yearly rate of decline in both forced vital capacity and forced expiratory volume in 1 s (3.2% and 1.7% versus 1.7% and 0.9%, respectively) and manifold increased yearly rate of loss of lean body mass (0.18 kg·m(-2) versus 0.03 kg·m(-2) among those who did not desaturate).Desaturating COPD patients had a significantly worse prognosis than non-desaturating COPD patients, for multiple important disease outcomes.

Participation in research bronchoscopy: a literature review

Bronchoscopy is the preferred method for collecting biological samples from the lower airways of subjects in clinical research. However, ensuring participation in clinical research can be challenging when the research includes an invasive procedure. For this report we reviewed the literature to look for information on participation in research bronchoscopy studies to better design our own study, the Bergen COPD Microbiome study (MicroCOPD). We performed a systematic literature search on participation in research bronchoscopy studies in February 2014 using the search engines of PubMed and EMBASE. The literature search resulted in seven relevant papers. Motivation was an end point in six of the seven papers, but reasons for declining participation and recruitment strategies also seemed important. Human subjects participate in research bronchoscopy studies for personal benefit and altruistic reasons. Inconvenience associated with research, in addition to fear of procedures, is considered a barrier. Radio, especially news stations, generated the most inquiries for a clinical study involving bronchoscopy. There is a lack of information on participation in research bronchoscopy studies in the literature. A bronchoscopy study has been initiated at Haukeland University Hospital, Bergen, Norway, to examine the role of the microbiome in COPD, and participation will be explored as a substudy.

Is sense of coherence a predictor of lifestyle changes in subjects at risk for type 2 diabetes?

OBJECTIVE

To determine whether the sense of coherence (SOC) could predict the outcome of an 18-month lifestyle intervention program for subjects at risk of type 2 diabetes.

METHODS

Subjects at high risk of type 2 diabetes mellitus were recruited to a low-intensity lifestyle intervention program by their general practitioners. Weight reduction ≥ 5% and improvement in exercise capacity of ≥ 10% from baseline to follow-up indicated a clinically significant lifestyle change. SOC was measured using the 13-item SOC questionnaire.

RESULTS

The study involved 213 subjects with a mean body mass index of 37 (SD ± 6). Complete follow-up data were obtained for 131 (62%). Twenty-six participants had clinically significant lifestyle changes. There was a 21% increase in the odds of a clinically significant lifestyle change for each point increase in the baseline SOC score (odds ratio = 1.21; confidence interval = 1.11-1.32). The success rate was 14 times higher in the highest SOC score tertile group compared with the lowest.

CONCLUSION

High SOC scores were good predictors of successful lifestyle change in subjects at risk of type 2 diabetes. SOC-13 can be used in daily practice to increase clinical awareness on the impact of mastery on the outcome of life-style intervention programs.

Predictors for PaO2 and hypoxemic respiratory failure in COPD-A three-year follow-up

BACKGROUND

Knowledge about predictors for developing hypoxemia in the course of chronic obstructive pulmonary disease (COPD) progression is limited. The objective of the present study was to investigate predictors for overall PaO2, for a potential change in PaO2 over time, and for first occurrence of hypoxemia.

METHODS

419 patients aged 40-76 years with COPD GOLD stages II-IV underwent clinical and pulmonary function measurements, including repeated arterial blood gases over three years. Airway obstruction, lung hyperinflation, markers of systemic inflammation and cardiovascular health, exacerbation frequency, smoking habits, and body composition were tested as possible predictors of PaO2 and first episode of hypoxemia.

RESULTS

In multivariate adjusted longitudinal analyses, forced expiratory volume in 1 second, total lung capacity and functional residual capacity (all in% predicted), resting heart rate and fat mass index were all associated with overall PaO2 (all P < 0.005). We found no change in PaO2 over time (ρ = 0.33), nor did we find evidence that any of the tested variables predicted change in PaO2 over time. In multivariate adjusted survival analyses, functional residual capacity and resting heart rate were predictors of episodic hypoxemia (both ρ < 0.005).

CONCLUSIONS

This longitudinal study identified pulmonary, cardiac and metabolic risk factors for overall PaO2 and episodic hypoxemia, but detected no change in PaO2 over time.

No impact of early real-time PCR screening for respiratory viruses on length of stay and use of antibiotics in elderly patients hospitalized with symptoms of a respiratory tract infection in a single center in Norway

We tested the hypothesis that the results of real-time polymerase chain reaction (PCR) analyses for respiratory viruses would reduce antibiotic treatment and length of stay in elderly patients hospitalized with respiratory infections. Within 24 h of hospital admission, a total of 922 patients aged ≥60 years were interviewed for symptoms of ongoing respiratory tract infection. Symptomatic patients were swabbed for oropharyngeal/nasopharyngeal presence of viral pathogens immediately by members of the study group. During a 2-month period, non-symptomatic volunteers among interviewed patients were swabbed as well (controls). Oropharyngeal/nasopharyngeal swabs were analyzed with real-time PCR for nine common respiratory viruses. A total of 147 out of 173 symptomatic patients and 56 non-symptomatic patients (controls) agreed to participate in the study. The patients were allocated to three cohorts: (1) symptomatic and PCR-positive (S/PCR+), (2) symptomatic and PCR-negative (S/PCR−), or (3) non-symptomatic and PCR-negative (control). There were no non-symptomatic patients with a positive PCR result. A non-significant difference in the frequency of empiric antibiotic administration was found when comparing the S/PCR+ to the S/PCR− cohort; 16/19 (84 %) vs. 99/128 (77 %) (χ² = 0.49). Antibiotic treatment was withdrawn in only two patients in the S/PCR+ cohort after receiving a positive viral diagnosis. The length of stay did not significantly differ between the S/PCR+ and the S/PCR− groups. We conclude that, at least in our general hospital setting, access to early viral diagnosis by real-time PCR had little impact on the antimicrobial treatment or length of hospitalization of elderly patients.

Chronic obstructive pulmonary disease is associated with low levels of vitamin D

Introduction

COPD patients may be at increased risk for vitamin D (25(OH)D) deficiency, but risk factors for deficiency among COPD patients have not been extensively reported.

Methods

Serum 25(OH)D levels were measured by liquid chromatography double mass spectrometry in subjects aged 40–76 years from Western Norway, including 433 COPD patients (GOLD stage II-IV) and 325 controls. Levels <20 ng/mL defined deficiency. Season, sex, age, body mass index (BMI), smoking, GOLD stage, exacerbation frequency, arterial oxygen tension (PaO₂), respiratory symptoms, depression (CES-D score≥16), comorbidities (Charlson score), treatment for osteoporosis, use of inhaled steroids, and total white blood count were examined for associations with 25(OH)D in both linear and logistic regression models.

Results

COPD patients had an increased risk for vitamin D deficiency compared to controls after adjustment for seasonality, age, smoking and BMI. Variables associated with lower 25(OH)D levels in COPD patients were obesity ( = −6.63), current smoking ( = −4.02), GOLD stage III- IV ( = −4.71, = −5.64), and depression ( = −3.29). Summertime decreased the risk of vitamin D deficiency (OR = 0.22).

Conclusion

COPD was associated with an increased risk of vitamin D deficiency, and important disease characteristics were significantly related to 25(OH)D levels.

Recommendations for epidemiological studies on COPD

The prevalence of chronic obstructive pulmonary disease (COPD) has been extensively studied, especially in Western Europe and North America. Few of these data are directly comparable because of differences between the surveys regarding composition of study populations, diagnostic criteria of the disease and definitions of the risk factors. Few community studies have examined phenotypes of COPD and included other ways of characterising the disease beyond that of spirometry. The objective of the present Task Force report is to present recommendations for the performance of general population studies in COPD in order to facilitate comparable and valid estimates on COPD prevalence by various risk factors. Diagnostic criteria in epidemiological settings, and standardised methods to examine the disease and its potential risk factors are discussed. The paper also offers practical advice for planning and performing an epidemiological study on COPD. The main message of the paper is that thorough planning is worth half the study. It is crucial to stick to standardised methods and good quality control during sampling. We recommend collecting biological markers, depending on the specific objectives of the study. Finally, studies of COPD in the population at large should assess various phenotypes of the disease.

Efficacy and safety of 4 weeks' treatment with combined fluticasone furoate/vilanterol in a single inhaler given once daily in COPD: a placebo-controlled randomised trial

Background Fluticasone furoate/vilanterol (FF/VI) is a novel once-daily (OD) inhaled corticosteroid/long-acting β(2) agonist combination in development for chronic obstructive pulmonary disease (COPD) and asthma. Trial design A multicentre, randomised, double-blind, parallel-group, placebo-controlled study. Methods Participants were patients with moderate-to-severe COPD treated with placebo or FF/VI 400/25 μg OD for 4 weeks. Study objectives were to assess the safety and efficacy of FF/VI 400/25 μg OD administered for 4 weeks via a novel dry powder inhaler. Co-primary end points were change from baseline in weighted mean (wm) heart rate 0-4 h postdose at day 28 and the incidence of adverse events (AEs). Secondary end points included change from baseline in trough forced expiratory volume in one second (FEV(1)) (23-24 h postdose; day 29) and wm FEV(1) (0-4 h postdose; day 28). Patients were randomised to receive FF/VI 400/25 μg or placebo in a 2:1 ratio; all patients and investigators were blinded to active or placebo treatment. Results 60 patients (mean age 64 years) were randomised (FF/VI: n=40; placebo: n=20), and all contributed data to the analysis. Mean screening post-bronchodilator FEV(1) per cent predicted was comparable between groups (FF/VI: 58.5%; placebo: 60.1%). The wm heart rate 0-4 h postdose was similar between groups (difference: 0.6 beats per minute; 95% CI -3.9 to 5.1). More on-treatment AEs were reported in the FF/VI group (68%) compared with the placebo group (50%). The most common drug-related AEs in the FF/VI group were oral candidiasis (8%) and dysphonia (5%). There were no clinically relevant effects on laboratory values, including glucose and potassium, or on vital signs or ECGs/Holters. The FF/VI group had statistically greater improvements compared with placebo in trough FEV(1) (mean difference 183 ml) and 0-4 h postdose wm FEV(1) (mean difference 236 ml). Conclusion FF/VI has a good safety and tolerability profile and improves lung function compared with placebo in patients with COPD. Trial registration number clinical trials.gov-NCT00731822.

Excessive costs of COPD in ever-smokers. A longitudinal community study

AIM

We aimed to estimate the societal treatment-related costs of COPD in hospital- and population-based subjects with spirometry defined COPD, relative to a control group.

METHODS

81 COPD cases and 132 controls without COPD were randomly recruited from a general population, as were 205 COPD patients from a hospital register. All participants were ever-smokers of at least 40 years of age, followed for 12 months. Data on comorbid conditions and spirometry were collected at baseline. Standardized telephone interviews every third month gave information on use of healthcare services and exacerbations of respiratory symptoms.

RESULTS

The increased (excessive) median annual costs per case having stage II, stage III and stage IV COPD were € (95% CI) 400 (105-695), 1918 (1268-2569) and 1870 (1031-2709), respectively, compared to the population-based controls. Costs increased with €81 (95% CI 50-112) per exacerbation of respiratory symptoms and €461 (95% CI 354-567) per comorbid condition. Excessive costs for hospital COPD patients were threefold that of the population-based COPD cases.

CONCLUSION

The excessive treatment-related cost of COPD stage II+ in ever-smokers of at least 40 years was estimated to €105 million for Norway. Comorbidity was a dominant predictor of excessive cost in COPD.

Case-control studies on risk factors for chronic obstructive pulmonary disease: how does the sampling of the cases and controls affect the results?

INTRODUCTION

Sampling is regarded as crucial to the validity of case-control studies. Ideally, cases and controls should be selected from the same source population, but deviations from this approach are often seen.

OBJECTIVE

Our objective was to examine how exposure-disease relationships in a study on chronic obstructive pulmonary disease (COPD) were affected by the sampling sources of cases and controls.

METHODS

A Norwegian case-control study on COPD including 1909 subjects used three sources of recruitment for cases (general population, hospital registry and volunteers) and two sources for controls (general population and volunteers). This resulted in six sampling combinations of cases and controls (groups A-F). We examined how the risk factors gender, age, smoking, educational level and comorbidity were associated with COPD in these six sampling groups.

RESULTS

Several exposure-disease associations were dependent on variation in sampling source, thereby demonstrating the possibility of selection bias. The theoretically most ideal sampling group is likely group A, where both cases and controls are recruited from a general population. When using group A as a reference, the groups containing either voluntary controls and/or hospital-based cases deviated the most, suggesting higher susceptibility to selection bias in these groups.

CONCLUSION

Recruitment from several sources made our study design vulnerable to selection bias. Our findings should bring about increased awareness to the sampling process, and encourage sampling of cases and controls from the same source population in future studies.

Swabbing for respiratory viral infections in older patients: a comparison of rayon and nylon flocked swabs

The purpose of this study was to compare the sampling efficacy of rayon swabs and nylon flocked swabs, and of oropharyngeal and nasopharyngeal specimens for the detection of respiratory viruses in elderly patients. Samples were obtained from patients 60 years of age or above who were newly admitted to Sorlandet Hospital Arendal, Norway. The patients were interviewed for current symptoms of a respiratory tract infection. Using rayon swabs and nylon flocked swabs, comparable sets of mucosal samples were harvested from the nasopharynx and the oropharynx. The samples were analysed using real-time polymerase chain reaction (PCR) methods. A total of 223 patients (mean age 74.9 years, standard deviation [SD] 9.0 years) were swabbed and a virus was recovered from 11% of the symptomatic patients. Regardless of the sampling site, a calculated 4.8 times higher viral load (95% confidence interval [CI] 1.3-17, p = 0.017) was obtained using the nylon flocked swabs as compared to the rayon swabs. Also, regardless of the type of swab, a calculated 19 times higher viral load was found in the samples from the nasopharynx as compared to the oropharynx (95% CI 5.4-67.4, p < 0.001). When swabbing for respiratory viruses in elderly patients, nasopharyngeal rather than oropharyngeal samples should be obtained. Nylon flocked swabs appear to be more efficient than rayon swabs.

Aspects of healthcare utilisation in self-reported obstructive lung disease

INTRODUCTION

Utilisation of healthcare resources because of pulmonary diseases have previously been presented according to lung function or symptom severity. We aimed to compare the associations of symptoms and lung function to healthcare and social service utilisation in subjects with self-reported obstructive lung diseases (OLDs) (asthma, chronic obstructive pulmonary disease, chronic bronchitis, emphysema).

MATERIALS AND METHODS

Of 2819 participants aged 27-82 years in the Hordaland County Respiratory Health Survey, 200 subjects (7.1%) self-reported OLD. They answered 13 questions on respiratory symptoms and 5 questions on use of healthcare and social services. Altogether, 161 participants (81%) completed post-bronchodilation spirometry.

RESULTS

Use of anti-asthmatic drugs, regular physician's appointment, sick leave payment for the last 12 months, hospital admission for the last 12 months and disability pension were reported by 68%, 63%, 18%, 8% and 7% of those with self-reported OLD, respectively. Twenty per cent of subjects with self-reported OLD had not received any healthcare or social services. In adjusted multivariate logistic regression analyses, increase in the respiratory symptom score was significantly associated with more healthcare and social services. Lower forced expiratory volume in 1 s in % predicted, however, was not significantly associated with more use of healthcare and social services.

CONCLUSION

The majority (80%) of subjects in a general population with self-reported OLD received healthcare services. The utilisation of healthcare and social services was strongly associated to the burden of respiratory symptoms, and, to a lesser degree, to the level and pattern of lung function.

Norwegian population surveys on respiratory health in adults: objectives, design, methods, quality controls and response rates

BACKGROUND AND AIMS

Quantifying the prevalence of asthma, chronic obstructive pulmonary disease (COPD) and restrictive pulmonary diseases in Norway is needed to document the burden of chronic respiratory inflammatory diseases on disability, health care costs and impaired quality of life. To introduce effective interventions for prevention, cure and care, there is a prerequisite to know the environmental causes. Furthermore, using relevant and precise phenotypes from community-based studies are important for detecting molecular-genetic causes for diseases.

METHODS

The Norwegian Population Survey Initiative on Respiratory Health in Adults has, for four decades, applied international standardised methods for the recording of respiratory symptoms, health status, exposure to risk factors, socio-economic factors and the use of health services. Measurements of spirometry, metacholine bronchial responsiveness, transfer factor for carbon monoxide, atopy as well as chest X-ray examinations have been used advocating the internationally accepted methods. All surveys had similar quality controls, supervision and training of the field-worker team.

RESULTS

From 1965 to 1999, random population samples, altogether including 178 690 individuals, have been invited by random sampling to seven surveys on respiratory health in the counties of Oslo (39 998 people) and Hordaland (138 692 people). The surveys were initiated in 1964, 1972, 1985, 1988, 1991 and two in 1998. The age span of those invited persons varied from 15 to 74 years at baseline. It included 43 330 women and 135 537 men. Altogether 130 075 (73%) persons participated by returning an answered questionnaire. Spirometry results are available from 41 335 persons at baseline. A biobank for DNA and blood markers has been established. Data from longitudinally clinical-epidemiological studies were available by 2007, for three surveys after 20 years, 10 years and 6-7 years, and also for parts of three other surveys, while one survey has been examined for cause-specific mortality after 30 years. The response rates of the baseline studies varied from 90% to 68% of those invited and, in general, it has declined over 35 years. The response rate of the longitudinal studies with follow-ups also declined with time after the baseline study.

CONCLUSIONS

Great challenges for future population-based studies are (i) to keep the participation rates high in community studies; (ii) to standardise the basic clinical-epidemiological methods over decades of follow-up and to systematically transfer these methods into new populations with different languages and cultures and (iii) to focus on important research questions on respiratory health for the community.

Body composition and plasma levels of inflammatory biomarkers in COPD

Previous studies suggest a relationship between systemic inflammation and body composition in chronic obstructive pulmonary disease (COPD). We examined the relationships between body composition (fat free mass index (FFMI) kg·m(-2) and fat mass index (FMI) kg·m(-2)) and three plasma inflammatory markers C-reactive Protein (CRP), soluble tumour necrosis factor receptor 1 (sTNF-R1) and osteoprotegerin (OPG) in 409 stable COPD patients (aged 40-75 yrs, Global Initiative for Obstructive Chronic Lung Disease (GOLD) categories II-IV, 249 male) from the Bergen COPD Cohort Study in Norway. FFMI and FMI were measured by bioelectrical impedance. Plasma CRP (μg·mL(-1)), sTNF-R1 (pg·mL(-1)) and OPG (ng·mL(-1)) were determined by enzyme immunoassays. Correlations and Kruskal-Wallis tests were used for bivariate analyses. Linear regression models were fitted for each of the three markers, CRP, sTNF-R1 and OPG, with FFMI and FMI as explanatory variables including sex, age, smoking habits, GOLD category, hypoxaemia, Charlson Comorbidity Index and inhaled steroid use as potential confounders. CRP and sTNF-R1 levels correlated positively with both FFMI and FMI. The adjusted regression coefficients for an increase in logCRP per unit increase in FFMI was 1.23 (1.14-1.33) kg·m(-2) and 24.9 (11.8-38.1) kg·m(-2) for sTNF-R1. Higher FMI was associated with a lower OPG, with adjusted regression coefficient -0.14 (-0.23- -0.04), whereas FFMI was unrelated to OPG. In conclusion, COPD patients with low FFMI had lower not higher plasma levels of CRP and sTNF-R1, whereas higher fat mass was associated with higher CRP and sTNF-R1 and lower OPG.

Socioeconomic risk factors for lung function decline in a general population

The aim of our study was to examine sex-specific associations between different aspects of socioeconomic status (SES) (educational level, occupational status, income) and lung function in a general adult population. In the Hordaland County Cohort Study, 1,644 subjects aged 26-82 yrs at baseline answered questionnaires and performed post-bronchodilator spirometry both in 1996-1997 and in 2003-2006. We performed adjusted linear regression analysis on the effect of SES on decline in forced experimental volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC. Mean annual decline in FEV(1) from baseline to follow-up was 57 mL (se 1.3) and 48 mL (se 1.0) for males and females, respectively. Males had a larger decline in FVC than females, while females had a larger decline in FEV(1)/FVC. Lower education and low occupational status were associated with larger male lung function decline. SES did not affect female lung function decline. However, marital status was a significant predictor; unmarried females had less decline than both married and widowed females in both FEV(1) (adjusted mean annual difference 8 mL and 16 mL) and FVC (adjusted mean annual difference 8 mL and 18 mL). Low SES was associated with increased lung function decline in males. For females, marital status was more important.

Systemic inflammatory markers in COPD: results from the Bergen COPD Cohort Study

Chronic obstructive pulmonary disease (COPD) is considered an inflammatory pulmonary disorder with systemic inflammatory manifestations. The aim of this study was to assess the systemic levels of six inflammatory mediators in a large cohort of COPD patients and controls. 409 COPD patients and 231 healthy subjects, aged 40-75 yrs, were included from the first phase of the Bergen COPD Cohort Study. All COPD patients were clinically diagnosed by a physician, and had a forced expiratory volume in 1 s/forced vital capacity ratio less than 0.7 and a smoking history of >10 pack-yrs. The plasma levels of C-reactive protein (CRP), soluble tumour necrosis factor receptor (sTNFR)-1, osteoprotegrin, neutrophil activating peptide-2, CXCL16 and monocyte chemoattractant protein-4 were determined by ELISA. After adjustment for all known confounders, COPD patients had significantly lower levels of osteoprotegrin than subjects without COPD (p<0.05), and higher levels of CRP (p<0.01). Among COPD patients, CRP was elevated in patients with frequent exacerbations (p<0.05). sTNFR-1 and osteoprotegrin were both related to Global Initiative for Chronic Obstructive Lung Disease stage and frequency of exacerbations in the last 12 months (p<0.05). In addition, sTNFR-1 was significantly associated with important comorbidities such as hypertension and depression (p<0.05). The present study confirms that certain circulating inflammatory mediators are an important phenotypic feature of COPD.

Transthoracic fine-needle aspiration in the aetiological diagnosis of community-acquired pneumonia

Clin Microbiol Infect 2010; 16: 909–911

Abstract

To investigate the safety and practicability of conducting transthoracic fine‐needle aspiration (TFNA) in a general hospital setting, we applied the TFNA procedure to 20 patients hospitalized with community‐acquired pneumonia (CAP) within 36 h of admission. Also, a preliminary assessment was made of the potential value of adding TFNA to conventional methods of diagnostic microbiology. TFNA was easy to perform and caused little discomfort, and no serious adverse events were observed. In spite of ongoing antimicrobial treatment, a likely aetiological diagnosis was established for 14 of 20 (70%) of the patients. TFNA may provide important additional information on the aetiology of CAP.

Relationships between hand-rolled cigarettes and primary lung cancer: a Norwegian experience

INTRODUCTION

Detailed smoking history of patients developing lung cancer is rarely known, especially not for users of hand-rolled cigarettes. In Norway, smoking hand-rolled tobacco is still popular, accounting for one-third of the total tobacco consume.

METHODS

A questionnaire-based study revealing detailed information about tobacco consume with consecutive inclusion of all persons developing lung cancer in Southern Norway 2002-2005.

RESULTS

In this unselected population with 479 patients with newly diagnosed lung cancer, 95% had a smoking history and 88% of ever-smokers had smoked primarily hand-rolled cigarettes. The hand-rolled cigarette smokers had smoked fewer cigarettes daily (15) and less pack-years of tobacco (34) than fabricated cigarette smokers (20, P < 0.0001 and 42, P = 0.021, respectively). Smoking hand-rolled cigarettes was considerably more frequent than expected from official sales statistics. Hand-rolled cigarette smoking revealed an odds ratio of 13 for developing lung cancer compared with smoking fabricated cigarettes.

CONCLUSION

In this unselected population with newly diagnosed lung cancer, nine out of 10 ever-smokers had smoked primarily hand-rolled cigarettes. Patients smoking hand-rolled cigarettes had a smoking history of fewer daily cigarettes and less pack-years tobacco consumed than fabricated cigarette smokers. In this study, hand-rolled cigarettes are more frequently used than shown in national statistics. Smokers of hand-rolled cigarettes may have a greatly increased risk for lung cancer compared with smokers of fabricated cigarettes.

Quantitative computed tomography: emphysema and airway wall thickness by sex, age and smoking

We investigated how quantitative high-resolution computed tomography (HRCT) measures of emphysema and airway wall thickness (AWT) vary with sex, age and smoking history. We included 463 chronic obstructive pulmonary disease (COPD) cases and 431 controls. All included subjects were current or ex-smokers aged > or = 40 yrs, and all underwent spirometry and HRCT examination. The HRCT images were quantitatively assessed, providing indices on lung density and airway dimensions. The median (25-75th percentile) %LAA950 (% low-attenuation area < -950 HU) was 8.9 (3-19) and 4.7 (1-16) in male and female COPD cases, respectively, and 0.71 (0.3-1.6) and 0.32 (0.1-0.8) in male and female controls, respectively. %LAA950 was higher in ex-smokers and increased with increasing age and with increasing number of pack-years. The mean+/-SD standardised AWT was 0.504+/-0.030 and 0.474+/-0.031 in male and female COPD cases, respectively, and 0.488+/-0.028 and 0.463+/-0.025 in male and female controls, respectively. AWT decreased with increasing age in cases, and increased with the degree of current smoking in all subjects. We found significant differences in quantitative HRCT measures of emphysema and AWT between varying sex, age and smoking groups of both control and COPD subjects.

Clinical data discriminating between adults with positive and negative results on bronchodilator testing

OBJECTIVE

To evaluate how spirometry, symptoms and smoking discriminate between subjects who are responsive to bronchodilator testing and those who are non-responsive, and to examine how cut-off points of positive tests are related to symptoms of chronic obstructive pulmonary disease (COPD) and asthma.

METHODS

Subjects aged 47-48 and 71-73 years living in Bergen, Norway, were recruited. The 3506 participants (69%) filled in questionnaires and performed a bronchodilator test using salbutamol.

RESULTS

Tests were positive (forced expiratory volume in 1 s [Delta FEV1] >or=200 ml and >or=12%) in 107 subjects (3%). In logistic regression, spirometry (FEV1 < 80%, OR 6.0, 95%CI 3.6-10.2, and FEV1/FVC < 0.70, OR 3.1, 95%CI 1.9-5.2) and pack-years >or= 20 (OR 0.3, 95%CI 0.2-0.7), but not symptoms, predicted the test outcome. FEV1% and FEV1/forced volume capacity (FVC) discriminated equally well between positive and negative tests (area under the receiver operating characteristic [ROC] curve 0.81, 95%CI 0.77-0.85 vs. 0.77, 95%CI 0.72-0.82). The largest likelihood ratio for positive tests was 5.4 (95%CI 3.8-7.8) using FEV1 < 80% and FEV1/FVC < 0.70.

CONCLUSIONS

Spirometry and to a lesser extent smoking, but not symptoms, are useful in discriminating between middle-aged and elderly patients with positive and negative bronchodilator tests. Acute responses to salbutamol, expressed by commonly used Delta FEV1 cut-off points, are poorly related to COPD- and asthma-like symptoms.

Bronchodilator response to adrenergic beta2-agonists: relationship to symptoms in an adult community

BACKGROUND

Wheeze and chest tightness has traditionally been associated with enhanced bronchial responsiveness. However, no community studies are available on the associations between bronchodilator response and respiratory symptoms among adults.

AIM

To examine how respiratory symptoms predict bronchodilator response.

METHODS

An age and gender stratified random sample of all adults aged 47-48 and 71-73 years in Bergen, Norway, were invited. The 3506 participants (69%) filled in questionnaires including nine symptoms and performed bronchodilator reversibility tests. Subjects without current anti-asthmatic medication performing acceptable reversibility tests were included in the analyses (n=3088).

RESULTS

A reversibility with FEV(1) increase 12% and 200 ml was obtained in 2% of middle-aged and 4% of elderly subjects (p=0.001). In multiple linear regression analysis bronchodilatation was positively associated with wheezing without cold (FEV(1) increase of 1.5%, 95% CI: (0.9, 2.2)% in all participants and 31 ml, 95% CI: (1, 61)ml in men only) and dyspnoea climbing two flights of stairs (0.9%, 95% CI: (0.5,1.4)% and 12 ml, 95% CI: (1,23)ml). Chronic cough predicted the response negatively (-0.7%, 95% CI: (-1.3,-0.1)% and -17 ml, 95% CI: (-32,-2)ml). In multiple logistic regression analysis morning cough predicted an FEV(1) increase 12% and 200 ml (OR: 1.8, 95% CI: (1.1,2.8)).

CONCLUSIONS

A small fraction of adults in a general population has bronchodilatation after salbutamol inhalation. "Wheezing without cold", "dyspnoea climbing two flights of stairs", and "morning cough" predict an increased bronchodilator response among subjects without current anti-asthmatic medications.

[Instructing patients in the correct use of inhalation devices]

BACKGROUND

Limited knowledge is available on to what extent doctors and nurses know the correct use of various inhalation devices. We wanted to examine this skill among 25 doctors and 25 nurses randomly selected from the departments of pulmonology, internal medicine and surgery at a university hospital.

DESIGN

Two technicians asked them to demonstrate the correct use of a metered-dose inhaler (MDI), Turbuhaler and Diskus. The performance was checked against a list of criteria with a maximum obtainable score of 9 for each device.

RESULTS

The mean (SD) scores for the MDI, Turbuhaler and Diskus were 2.6 (2.0), 2.9 (2.2) and 3.7 (2.5), respectively. The score for the Diskus was significantly higher than those for the other two devices. The staff of the pulmonary department scored significantly higher than the staff of the other two departments, the scores for the pulmonary department being 4.1 (1.9), 4.8 (1.5) and 5.5 (1.5), respectively. The scores for the department of internal medicine were 2.4 (1.8), 2.7 (2.2) and 3.4 (2.5), and the scores for the department of surgery were 1.5 (1.2), 1.4 (1.5) and 2.3 (2.5).

INTERPRETATION

This study indicates that there is a significant potential for improvement in correct use of these inhalation devices.

Bronchodilator reversibility testing in an adult general population; the importance of smoking and anthropometrical variables on the response to a beta2-agonist

Normative cut-off values for the bronchodilator reversibility test are published neglecting factors that may influence the test result other than disease. The objective of this cross-sectional study of a general population was to examine how a salbutamol reversibility test response is depending on anthropometrical variables and smoking. An age and gender stratified random sample of all adults aged 47-48 and 71-73 years living in Bergen, Norway, was invited. The 3506 attendants (69%) filled in a questionnaire and performed spirometry before and after inhalation of 400 microg salbutamol. The mean (SD) absolute FEV(1) bronchodilator response, the change in % predicted, and the change in % initial among middle-aged were 71 (122) ml, 2.0 (3.3)%, and 2.4 (4.1)%, and in the elderly 64 (113) ml, 2.4 (4.3)% and 3.3 (5.9)%, respectively. In a multiple linear regression analysis including adjustment for the initial FEV1 in % predicted, smoking and pack-years were negatively correlated to all indices. Current smoking was considerably more important than past smoking. Female gender, old age, and BMI were positively correlated with the percentage change indices, but the correlation with BMI decreased with increasing heights. These trends were unchanged after excluding subjects with obstructive lung disease or coronary heart disease. This study demonstrates that smoking habits predict all indices expressing the salbutamol bronchodilator response among middle-aged and elderly from a general population. Also, the change in % predicted and the change in % initial indices are dependent on anthropometrical variables. However, although smoking and anthropometrical variables, as well as level of lung function predict the response to inhaled beta2-agonists, these factors explain only 7-16% of the total variation of the measurement indices, and seem therefore of minor importance to the interpretation of the test result.

Implications of reversibility testing on prevalence and risk factors for chronic obstructive pulmonary disease: a community study

BACKGROUND

The Global Initiative for Obstructive Lung Disease (GOLD) has defined chronic obstructive pulmonary disease (COPD) as a post-bronchodilator ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) of <0.7. In the first general population based study to apply post-bronchodilator values, the prevalence and predictors of GOLD defined COPD were assessed and the implications of beta2 agonist reversibility testing examined.

METHODS

Based on a random population sample, 2235 subjects (77%) aged 26-82 years performed spirometric tests before and 15 minutes after inhaling 0.3 mg salbutamol.

RESULTS

The prevalence of GOLD defined COPD was 7.0% (95% confidence interval (CI) 5.9 to 8.0). This estimate was 27% lower than COPD defined without bronchodilatation. One percent of the population had severe or very severe COPD. Compared with women, men had 3.1 (95% CI 2.1 to 4.8) times higher odds for COPD. Subjects with a smoking history of more than 20 pack years had an odds ratio (OR) of 6.2 (95% CI 3.4 to 11.0) for COPD relative to never-smokers, while subjects older than 75 years had an OR of 18.0 (95% CI 9.2 to 35.0) relative to those below 45 years. Subjects with primary education only had an OR of 2.8 (95% CI 1.4 to 5.3) compared with those with university education. Subjects with body mass index (BMI) <20 kg/m2 were more likely than subjects with BMI 25-29.9 kg/m2 to have COPD (OR 2.4, 95% CI 1.1 to 5.3). The adjusted proportion of COPD attributable to smoking was 68%.

CONCLUSIONS

These results indicate that community programmes on prevention of COPD should focus on anti-smoking, nutritional aspects, and socioeconomic conditions. The effect of beta2 reversibility testing on prevalence estimates of COPD was substantial.

Indoor exposures and respiratory symptoms in a Norwegian community sample

BACKGROUND

Limited data are available on the effect of a poor indoor climate on the respiratory health of adults. No data are available regarding the contribution of indoor exposures to the burden of respiratory symptoms in the population.

METHODS

In 1996-7 a community sample of 3181 adults aged 26-82 years was invited to participate in a survey on indoor climate and respiratory health in Hordaland County, Norway. 2401 subjects agreed to take part. Logistic regression was used to examine the relationship between eight markers of indoor exposure and physician diagnosed asthma and five respiratory symptoms, after adjustment for sex, age, smoking, educational level, smoking habits, pack years, and occupational airborne exposure.

RESULTS

Mould exposure was associated with all the respiratory symptoms; the adjusted odds ratios (OR) varied from 1.6 (95% confidence interval (CI) 1.0 to 2.4) for cough with phlegm to 2.3 (95% CI 1.4 to 3.9) for grade 2 dyspnoea. Keeping a cat or dog in childhood was associated with grade 2 dyspnoea and attacks of dyspnoea, with adjusted ORs of 1.3 (95% CI 1.0 to 1.7) and 1.4 (95% CI 1.1 to 1.8), respectively. Having a fitted carpet in the bedroom was negatively associated with three of the five respiratory symptoms. 3-5% of the frequency of the respiratory symptoms in the study population could be attributed to exposure to visible moulds.

CONCLUSION

Mould exposure is an independent risk factor for several respiratory symptoms in a general population covering a wide age span, but it makes only a small contribution to the respiratory symptom burden in the population at large.

The incidence of adult asthma: a review

In recent years, several new studies have estimated the incidence of adult asthma. These studies vary in design and quality. The current paper summarises the findings of major population studies in the adult incidence of asthma. The pooled estimate of the adult incidence of asthma was 4.6 per 1000 person-years in women and 3.6 per 1000 person-years in men. The estimate among only general population cohort studies was higher, respectively 5.9 and 4.4 per 1000 person-years in women and men. The adult incidence of asthma was slightly higher in women than men. In the few studies that allowed the incidence of asthma to be estimated among those aged >50 years, there was a trend towards a higher incidence with age. It is thought likely that this is at least partly explained by misclassification with COPD. However, the current findings from these studies may imply that the incidence of asthma in the elderly has previously been under-estimated. Finally, the review shows that estimates of adult asthma incidence have tended to be higher in later studies, implying a rise in asthma incidence in adults within the timeframe of observation.

Atopic and non-atopic asthma in a farming and a general population

BACKGROUND

In a previous study inverse associations between asthma and exposure to fungal spores and endotoxins in atopic farmers and positive associations with the same factors in non-atopic farmers were documented. No external reference population had been included. We, therefore, compared this farming population with the general population from an adjacent region.

METHODS

Random samples of a farming (n=2,106) and a rural (n=351) and urban (n=727) general population were selected. Atopy was assessed by serum IgE and asthma by questionnaires.

RESULTS

The asthma prevalence was 4.0% among farmers, 5.7% in the rural, and 7.6% in the urban population. Atopy was similar (9-10%). Most asthmatics were not atopic, 67-75%. Farmers had asthma less often than the general population OR 0.52 (95% CI 0.36-0.75); both atopic (OR 0.33 (95% CI 0.15-0.69)) and non-atopic asthma (OR 0.60 (95% CI 0.39-0.93)).

CONCLUSION

This may indicate a protective effect of the farm environment on asthma but a healthy worker effect may also play a role.

Pulmonary gas exchange and educational level: a community study

Socio-economic status (SES) is related to increased risk of airway disease in terms of forced expiratory volume in one second (FEV1) and forced vital capacity. No data are available as to what extent SES predicts alveolar function in a general population. In this cross-sectional study, 1,275 subjects aged 18-73 yrs underwent pulmonary testing, including the single-breath carbon monoxide transfer capacity of the lungs (TL,CO). Educational level was used as an index for SES. Mean +/- SD TL,CO % predicted was 97% among those with primary school education, 99% among those with secondary school education and 104% among those with a university degree. In a multiple linear regression analysis, adjusting for age, height, haemoglobin, carboxyhaemoglobin, smoking habits, occupational exposure, FEV1 and body mass index, TL,CO was significantly related to educational level in males but not in females. Occupational exposure was not significant. In this study, socio-economic status was found to be an independent determinant of TL,CO. Even in an affluent country such as Norway, socio-environmental risk factors may differ based on individuals' SES. Such risk factors may, for instance, be higher exposure to airborne pollutants, poorer housing conditions, or lower consumption of fruit and vegetables. Further exploration is called for.

Remission of respiratory symptoms by smoking and occupational exposure in a cohort study

Few studies have estimated the remission rates of respiratory symptoms in general populations. No community cohort studies have examined the impact of smoking cessation and previous dust or fumes exposure on the remission of respiratory symptoms. In the Hordaland County Study, an 11-yr community cohort (1985-1996/1997) from Western Norway, data from 2,819 subjects were used to examine the remission of six respiratory symptoms. The measured cumulative remission varied from 42.3% for morning cough to 58.4% for chronic cough. Smoking cessation was a significant predictor of remission of the cough symptoms and wheezing, with odds ratios (OR) (95% confidence intervals (CI)) varying from 2.2 (1.3-3.7) for wheezing to 6.2 (3.5-11.2) for morning cough, after adjustment for sex, age, pack-years smoked, previous dust or fumes exposure, and educational level. In those not previously exposed to dust or fumes, the adjusted OR (95% CI) for the remission of morning cough, phlegm cough, dyspnoea grade 2, attacks of dyspnoea and wheezing varied from 1.5 (0.9-2.5) for attacks of dyspnoea to 2.1 (1.1-3.9) for dyspnoea grade 2, as compared to those previously exposed to dust or fumes. This study suggests a beneficial effect of smoking cessation and an adverse effect of occupational exposure on the remission of respiratory symptoms.

Factors affecting growth of FEV1

There is an increasing awareness that also growth in FEV1 may be of importance to development of chronic obstructive lung disease in later life. This paper reviews current knowledge on factors in foetal and childhood life that may reduce lung growth. Passive smoking as well as malnutrition in foetal life is related to impaired lung function in later life. Birth weight is a risk factor to lung growth independent of gestational age and maternal smoking. Active and passive smoking in childhood and adolescence reduces growth. Girls seem to be more vulnerable than boys to the effect of smoking. Also host characteristics like atopy, bronchial hyper responsiveness and asthma are related to impaired growth of FEV1. Lower respiratory tract infections before the age of seven are also related to impaired lung growth in adult life. Although several studies have found socioeconomic status among adults related to chronic obstructive lung disease, it is not known to what extent low socioeconomic status affects growth of lung function after adjusting for risk factors like active and passive smoking and lower respiratory tract infections. Normal lung growth varies with age and between male and female. The importance of the various risk factors may differ depending at what point in the lung growth they come into play. Limited data is available about the interrelationship between the risk factors and the mechanisms through which they work.

Does smoking affect the outcome of patient education and self-management in asthmatics?

Information on the potential effect of smoking on the outcome of patient education in asthma is lacking. We randomly allocated 78 asthmatics to either a control or intervention group. Intervention consisted of two 2-h group sessions followed by 1-2 individual sessions each by a nurse and a physiotherapist. Self-management was emphasised following a stepwise treatment plan at exacerbations. Smokers experienced more general practitioner (GP) visits (P=0.001) and absenteeism from work (P=0.02), a greater need for rescue medication (P=0.03), a larger drop in FEV1 (P=0.02) and worse St. George's respiratory questionnaire (SGRQ) scores (P<0.001) compared to non-smokers during the 1-year follow-up. In multiple linear and logistic regression models smoking was still associated with worse SGRQ scores, a drop in FEV1, higher need for GP visits and rescue medication and higher total costs. We, thus, conclude that smoking was associated with reduced health related quality of life, a drop in FEV1, increased need for rescue medication and GP visits and higher costs after patient education during the 1-year follow-up, compared to no smoking.