Improvement of Phase Change Materials (PCM) Used for Solar Process Heat Applications.

The high intermittency of solar energy is still a challenge yet to be overcome. The use of thermal storage has proven to be a good option, with phase change materials (PCM) as very promising candidates. Nevertheless, PCM compounds have typically poor thermal conductivity, reducing their attractiveness for commercial uses. This paper demonstrates the viability of increasing the PCM effective thermal conductivity to industrial required values (around 4 W/m·K) by using metal wool infiltrated into the resin under vacuum conditions. To achieve this result, the authors used an inert resin, decoupling the specific PCM material selection from the enhancement effect of the metal wools. To ensure proper behavior of the metal wool under standard industrial environments at a broad range of temperatures, a set of analyses were performed at high temperatures and an inert atmosphere, presenting a thorough analysis of the obtained results.

Prevalence, Risk Factors and Diagnostic Accuracy of COPD Among Smokers in Primary Care.

The prevalence of COPD is high, and most cases remain undiagnosed. In contrast, some patients labeled and treated as COPD do not have spirometric confirmation. Our objective was to determine the prevalence of COPD among smokers aged 45 years or older and investigate the accuracy of diagnosis of COPD in primary care. A population-based, epidemiological study was conducted in a primary care centre among subjects older than 45 years with a history of smoking. The participants underwent a clinical questionnaire and spirometry with bronchodilator test. Additionally, participants with newly diagnosed COPD, defined as postbronchodilator FEV1/FVC<0.7, underwent 4-week treatment with formoterol and budesonide to rule out reversible airflow obstruction. A total of 1,738 individuals (84.4% male) with a mean age of 59.9 years were included. The prevalence of COPD was 24.3% (95%, CI 22.3-26.4), with an overall underdiagnosis of 56.7%. Patients with COPD were older, more frequently male, with a lower body mass index, a longer history of smoking, lower educational level, previous occupational exposure, and more cardiovascular co-morbidity (all p < 0.001). After 4 weeks of treatment, 16% of initially obstructed patients had normal spirometry; in addition, 15.6% of individuals with a diagnosis of COPD did not have airflow obstruction. One out of four smokers 45 years or older presenting in primary care have airflow obstruction, mostly undiagnosed. However, among those with an initial diagnosis of COPD up to 16% will normalise spirometry after 4 weeks of treatment. There is also a significant number of individuals misdiagnosed with COPD.

Anemia is a mortality predictor in hospitalized patients for COPD exacerbation.

BACKGROUND: Anemia is a recognized prognostic factor in many chronic illnesses, but there is limited information about its impact on outcomes in patients hospitalized for acute COPD exacerbation (AECOPD). AIM: To investigate whether anemia exerts an effect on mortality in patients admitted for AECOPD after one year of follow-up. Methods. From November 2007 to November 2009 we recruited 117 patients who required hospitalization due to an AECOPD. Clinical, functional and laboratory parameters on admission were prospectively assessed. Patients were followed up during one year. Mortality and days-to-death were collected. RESULTS: Mean age 72 (SD ± 9); FEV1 37.4 (SD ± 12); mortality after 1 year was 22.2%. Mean survival: 339 days. Comparing patients who died to those who survived we found significant differences (p < 0,000) in hemoglobin (Hb) (12.4 vs 13.8 mg/dl) and hematocrit (Ht) (38 vs 41%). Anemia (Hb < 13 g.dl⁻¹) prevalence was 33%. Those who died had experienced 3.5 exacerbations in previous year vs 1.5 exacerbations in the case of the survivors (p = 0.000). Lung function and nutritional status were similar, except for percentage of muscle mass (%) (35 vs 39%; p = 0.015) and albumin (33 vs 37 mg/dl; p = 0.039). These variables were included in a Multivariate Cox Proportional Hazards Model; anemia and previous exacerbations resulted as independent factors for mortality. Mortality risk for patients with anemia was 5.9(CI: 1.9-19); for patients with > 1 exacerbation in the previous year was 5.9(CI: 1.3-26.5). CONCLUSION: Anemia and previous exacerbations were independent predictors of mortality after one year in patients hospitalized for AECOPD.

Colour of sputum is a marker for bacterial colonisation in chronic obstructive pulmonary disease.

BACKGROUND: Bacterial colonisation in chronic obstructive pulmonary disease (COPD) contributes to airway inflammation and modulates exacerbations. We assessed risk factors for bacterial colonisation in COPD. METHODS: Patients with stable COPD consecutively recruited over 1 year gave consent to provide a sputum sample for microbiologic analysis. Bronchial colonisation by potentially pathogenic microorganisms (PPMs) was defined as the isolation of PPMs at concentrations of > or =102 colony-forming units (CFU)/mL on quantitative bacterial culture. Colonised patients were divided into high (>105 CFU/mL) or low (<105 CFU/mL) bacterial load. RESULTS: A total of 119 patients (92.5% men, mean age 68 years, mean forced expiratory volume in one second [FEV1] [% predicted] 46.4%) were evaluated. Bacterial colonisation was demonstrated in 58 (48.7%) patients. Patients with and without bacterial colonisation showed significant differences in smoking history, cough, dyspnoea, COPD exacerbations and hospitalisations in the previous year, and sputum colour. Thirty-six patients (62% of those colonised) had a high bacterial load. More than 80% of the sputum samples with a dark yellow or greenish colour yielded PPMs in culture. In contrast, only 5.9% of white and 44.7% of light yellow sputum samples were positive (P < 0.001). Multivariate analysis showed an increased degree of dyspnoea (odds ratio [OR] = 2.63, 95% confidence interval [CI] 1.53-5.09, P = 0.004) and a darker sputum colour (OR = 4.11, 95% CI 2.30-7.29, P < 0.001) as factors associated with the presence of PPMs in sputum. CONCLUSIONS: Almost half of our population of ambulatory moderate to very severe COPD patients were colonised with PPMs. Patients colonised present more severe dyspnoea, and a darker colour of sputum allows identification of individuals more likely to be colonised.

Diels-Alder reaction between cyclopentadiene and C60: an analysis of the performance of the ONIOM method for the study of chemical reactivity in fullerenes and nanotubes.

In this article, we theoretically analyze the Diels-Alder cycloaddition between cyclopentadiene and C60 for which experimental results on energy barriers and reaction energies are known. The comparison of the results obtained with the two-layered ONIOM approach using different partitions for the high- and low-level layers with those obtained employing the B3LYP/6-31G(d) method for the entire system allows us to conclude that the partition including a pyracylene unit of C60 in the description of the high-level layer is enough to get excellent results. Using this partition in the two-layered ONIOM approach, we have computed the energy barriers and reaction energies for this Diels-Alder reaction for different functionals, and we have compared them with experimental data. From this comparison, both the ONIOM2(M06-2X/6-31G(d):SVWN/STO-3G) and the M06-2X/6-31G(d)//ONIOM2(B3LYP/6-31G(d):SVWN/STO-3G) methods are recommended as reliable and computationally affordable approaches to be exploited for the study of the chemical reactivity of [6,6]-bonds in fullerenes and nanotubes.

[Phenotypic heterogeneity of chronic obstructive pulmonary disease]. / La heterogeneidad fenotípica de la EPOC.

A functional definition of chronic obstructive pulmonary disease (COPD) based on airflow limitation has largely dominated the field. However, a view has emerged that COPD involves a complex array of cellular, organic, functional, and clinical events, with a growing interest in disentangling the phenotypic heterogeneity of COPD. The present review is based on the opinion of the authors, who have extensive research experience in several aspects of COPD. The starting assumption of the review is that current knowledge on the pathophysiology and clinical features of COPD allows us to classify phenotypic information in terms of the following dimensions: respiratory symptoms and health status, acute exacerbations, lung function, structural changes, local and systemic inflammation, and systemic effects. Twenty-six phenotypic traits were identified and assigned to one of the 6 dimensions. For each dimension, a summary is provided of the best evidence on the relationships among phenotypic traits, in particular among those corresponding to different dimensions, and on the relationship between these traits and relevant events in the natural history of COPD. The information has been organized graphically into a phenotypic matrix where each cell representing a pair of phenotypic traits is linked to relevant references. The information provided has the potential to increase our understanding of the heterogeneity of COPD phenotypes and help us plan future studies on aspects that are as yet unexplored.

Persistence of Legionella in hospital water supplies and nosocomial Legionnaires' disease.

The molecular epidemiology of clinical and environmental Legionella species isolates was studied in seven hospitals from 1989 to 2006. The number of environmental pulsed field gel electrophoresis (PFGE) patterns ranged from one to nine according to the hospital. Genomic PFGE pattern persistence was observed in 71% of the hospitals, even after 17 years in some hospitals, and the relationship between environmental and clinical isolates was established. The isolates associated with hospital-acquired Legionnaires' disease corresponded to the persistent environmental PFGE patterns of Legionella pneumophila in potable water supplies.

Minimization of the environmental impact in the unhairing of bovine hides.

This study tests an alternative method to the traditional unhairing method used during the process of tanning the hides. The new method is based on the substitution of sodium sulfide by hydrogen peroxide as an unhairing agent in both hair recovery and recirculation of the floats employed in the process. The properties of the hides obtained using the two methods have been compared and the results indicate that those hides have similar physical, chemical, and organoleptic properties. However, the differences existing from an environmental point of view are significant. These include reductions of water consumption (approx 70%), chemical oxygen demand (approx 35%), toxicity (98%) and total kjendhal nitrogen (50%). Also, the risk associated with the production of hydrogen sulfide is eliminated, which implies a great improvement in terms of safety for the workers. Given the large amounts of water and chemical pollution discharged in the process, the reductions in absolute values represent a significant improvement. A financial assessment was carried out to demonstrate that the proposed new system is 16% more economic than the traditional one.

High chrome exhaustion in a non-float tanning process using a sulphonic aromatic acid.

Tanning processes performed in drums consume large amounts of water and chemicals, most of which end up in the wastewater. This study explores an alternative approach at an industrial scale to the traditional pickle-chrome tanning method. The new method replaces formic and sulphuric acids with sulphonic aromatic acid. Because it is done without float, there is a sizeable reduction in the amount of added salt and chrome salt as well as an increase in temperatures at the end of the tanning process. From an environmental perspective, the new method offers important advantages. For instance, there is no float addition in the tannage. Also, there are reductions of 94% and 99%, respectively, in the discharge of chlorides and chrome, as well as a 75% reduction in the residual float. Our financial assessment demonstrated that the new method is 42% cheaper than a traditional approach.

[Incidence and characteristics of adult-onset asthma]. / Incidencia y características del asma bronquial de inicio en la edad adulta.

OBJECTIVE: To determine the incidence of adult-onset asthma, along with lung function and immunologic characteristics, causes, and clinical course of the disease. PATIENTS AND METHODS: After identifying incident cases of asthma among adult residents of the district of North Barcelona, Spain, we proceeded to characterize the disease using a questionnaire, lung function tests, and skin allergy tests. Patients with an occupation associated with asthma, wheezing at work, and/or sensitization to workplace allergens were considered as having occupational asthma. The risk factors for developing chronic asthma were determined by multivariate analysis. RESULTS: In the 2-year study period, 218 incident cases of adult-onset asthma were identified (in a population of 68 067 adults, corresponding to an annual incidence of 160 per 100 000 per year). In total, 152 patients agreed to participate in the study (response rate, 70%); 140 reported wheezing and/or asthma in the last year (92%). The skin tests showed atopy in 57 cases (41%). Occupational asthma was diagnosed in 19 cases (14%). Domestic mammals were identified as causal agents in 8 patients (6%), drugs in 7 (5%), and environmental allergens in 44 (31%). Household cleaning was the occupation most frequently associated with the disease (26%). Of the 102 patients examined again after 2 years, 70 had chronic asthma (69%). Atopy (odds ratio [OR], 3.39; 95% confidence interval [CI], 1.15-9.99) and risk occupation when the disease was diagnosed (OR, 5.54; 95% CI, 1.05-29.11) were the factors associated with development of chronic disease. CONCLUSIONS: Occupation was related to adult-onset asthma in a little over 10% of the cases and was the main determinant of the development of chronic symptoms.

[Effect of AM3 on health-related quality of life in patients with chronic obstructive pulmonary disease belonging to risk groups]. / Efecto de AM3 en la calidad de vida de pacientes con enfermedad pulmonar obstructiva crónica en subgrupos de riesgo.

BACKGROUND AND OBJECTIVE: AM3 is an immunomodulator that significantly improves the quality of life of patients with chronic obstructive pulmonary disease (COPD). This study examined the effect of AM3 on the quality of life of patients in different risk groups and identified the factors associated with change in this variable. PATIENTS AND METHOD: This was a randomized, double-blind, placebo-controlled trial involving parallel groups of patients. The duration of the trial was 6 months. The study involved 253 patients with a mean (standard deviation) age of 67.7 (8.1) years and a mean forced expiratory volume in one second (FEV1) of 49.7% (10.2%). RESULTS: Only 121 patients (47.8%) suffered at least one exacerbation during the 6 months period. At the end of the study period, the improvement in St. George's Respiratory Questionnaire (SGRQ) score in those patients who suffered an exacerbation but who received AM3 was significantly greater than that experienced by similar placebo-treated patients (-8.10 compared to -2.5 units; p=0.034). Patients treated with inhaled corticoids also improved more with AM3 than with placebo (-9.17 compared to -4.44; p=0.035). In the 108 patients with an FEV1 of <50%, the improvements were not significantly different (-9.57 vs. -6.57; p=0.23). The factors influencing the change in SGRQ score were baseline SGRQ (p<0.001), exacerbations (p<0.008), an FEV1 of <50% (p<0.032) and treatment with AM3 (p<0.004). CONCLUSIONS: Among the patients who experienced exacerbations, treatment with AM3 helped prevent the deterioration of their quality of life. Along with AM3 treatment, the factors that independently influenced the change in SGRQ score were suffering from an exacerbation and poorer pulmonary function.

Minimization of the environmental impact of chrome tanning: a new process with high chrome exhaustion.

In all tanning technology operations wastes are generated. These reach the environment as residual waters, solid and liquid waste as well as atmospheric emissions and odours. This study tests an alternative method to the traditional tanning method at an industrial level. The new method is based on tanning without float and by significantly increasing the temperature at the end of the tanning process. The properties of the leathers obtained using the two methods have been compared and the results indicate that those leathers have similar physical, chemical, and organoleptic properties. However, the differences existing from the environmental point of view are significant. It is not necessary to use clean water for this tanning. Moreover, there is a 75% reduction of the residual float, a 91% reduction of the chrome discharged, and a 94% reduction of the chlorides discharged. A financial assessment was carried out to demonstrate that the newly proposed system is 32% more economic than the traditional one.

Impact of rapid urine antigen tests to determine the etiology of community-acquired pneumonia in adults.

STUDY OBJECTIVES: To evaluate the rapid urine antigen tests, including a new rapid immunochromatographic test (ICT) for the detection of the Streptococcus pneumoniae antigen and an enzyme immunoassay (EIA) for the detection of the Legionella antigen, in order to improve the diagnosis of community-acquired pneumonia (CAP) in adults. DESIGN: Prospective study. SETTING: A tertiary hospital in Spain. PATIENTS: We consecutively recruited 107 adults with CAP evaluated at our hospital. INTERVENTIONS: The analyses included blood and sputum cultures, pleural fluid culture (if present) and serologic studies. The detection of the Legionella pneumophila urinary antigen was performed by EIA, and the detection of S. pneumoniae antigen in urine samples was performed by counterimmunoelectrophoresis (CIE) and a rapid ICT. RESULTS: Using conventional microbiologic tests we succeeded in performing the etiologic diagnosis of 39 out of the 107 cases (36.4%). The inclusion of rapid antigen detection techniques increased the percentage of diagnosis to 54.2%, which represents a total increase of 17.8% (P=0.034). CONCLUSIONS: The data obtained in this study indicate that rapid urine antigen tests are very useful to determine CAP etiology in adults and, consequently, to quickly identify a group of patients in whom narrow spectrum antibiotics may be used.

Chronic respiratory symptoms, spirometry and knowledge of COPD among general population.

RATIONALE: Infradiagnosis of chronic obstructive pulmonary disease (COPD) may be related to the lack of knowledge about the disease and/or the scarce use of diagnostic procedures. This study analyses the frequency of respiratory symptoms and the knowledge about COPD in the general population, together with the use of spirometry in individuals at risk of COPD. POPULATION AND METHOD: A telephone survey was carried out in 6758 subjects older than 40 years, stratified by age, habitat (urban or rural) and region, screened by random-digit dialling. RESULTS: Up to 24% reported having at least one chronic respiratory symptom and 20.9% had a self-reported respiratory diagnosis. A total of 19.2% were active smokers and 40% had never tried to quit. Only 60% of the individuals with chronic symptoms had consulted a physician and, of them, only 45% had undergone spirometry. Spirometry was mentioned more frequently by subjects attended by pulmonologists than by GPs (67.6 vs. 28.6%; P<0.001). The term COPD was identified only by 8.6% of the participants. CONCLUSIONS: Many individuals with respiratory symptoms do not request medical attention and do not attempt to quit smoking. There is a lack of knowledge about COPD. Physicians should more actively inform about the disease and increase the use of spirometry for early detection.

Microbiologic determinants of exacerbation in chronic obstructive pulmonary disease.

BACKGROUND: The culture of bronchial secretions from the lower airway has been reported to be positive for potentially pathogenic microorganisms (PPMs) in patients with stable chronic obstructive pulmonary disease (COPD), but the determinants and effects of this bacterial load in the airway are not established. METHODS: To determine the bronchial microbial pattern in COPD and its relationship with exacerbation, we pooled analysis of crude data from studies that used protected specimen brush sampling, with age, sex, smoking, lung function, and microbiologic features of the lower airway as independent variables and exacerbation as the outcome, using logistic regression modeling. RESULTS: Of 337 study participants, 70 were healthy, 181 had stable COPD, and 86 had exacerbated COPD. Differences in the microbial characteristics in the participating laboratories were not statistically significant. A cutoff point of 10(2) colony-forming units (CFU) per milliliter or greater for the identification of abnormal positive culture results for PPMs was defined using the 95th percentile in the pooled analysis of healthy individuals. Bronchial colonization of 10(2) CFU/mL or greater by PPMs was found in 53 patients with stable COPD (29%) and in 46 patients with exacerbated COPD (54%) (P<.001, chi(2) test), with a predominance of Haemophilus influenzae and Pseudomonas aeruginosa. Higher microbial loads were associated with exacerbation and showed a statistically significant dose-response relationship after adjustment for covariates (odds ratio, 3.62; 95% confidence interval, 1.47-8.90), but P aeruginosa persisted as a statistically significant risk factor after adjustment for microbial load (odds ratio, 11.12; 95% confidence interval, 1.17-105.82). CONCLUSIONS: One quarter of the patients with COPD are colonized by PPMs during their stable periods. Exacerbation is associated with the overgrowth of PPMs and with the appearance of P aeruginosa in the lower airway, which is associated with exacerbation symptoms independent of load.

Automatic Video Analysis for Obstructive Sleep Apnea Diagnosis.

STUDY OBJECTIVES: We investigated the diagnostic accuracy for the identification of obstructive sleep apnea (OSA) and its severity of a noninvasive technology based on image processing (SleepWise). METHODS: This is an observational, prospective study to evaluate the degree of agreement between polysomnography (PSG) and SleepWise. We recruited 56 consecutive subjects with suspected OSA who were referred as outpatients to the Sleep Unit of the Hospital Universitari Germans Trias i Pujol (HUGTiP) from January 2013 to January 2014. All patients underwent laboratory PSG and image processing with SleepWise simultaneously the same night. Both PSG and SleepWise analyses were carried independently and blindly. RESULTS: We analyzed 50 of the 56 patients recruited. OSA was diagnosed through PSG in a total of 44 patients (88%) with a median apnea-hypopnea index (AHI) of 25.35 (24.9). According to SleepWise, 45 patients (90%) met the criteria for a diagnosis of OSA, with a median AHI of 22.8 (22.03). An analysis of the ability of PSG and SleepWise to classify patients by severity on the basis of their AHI shows that the two diagnostic systems distribute the different groups similarly. According to PSG, 23 patients (46%) had a diagnosis of severe OSA, 11 patients (22%) moderate OSA, and 10 patients (20%) mild OSA. According to SleepWise, 20, 13, and 12 patients (40%, 26%, and 24%, respectively) had a diagnosis of severe, moderate, and mild OSA respectively. For OSA diagnosis, SleepWise was found to have sensitivity of 100% and specificity of 83% in relation to PSG. The positive predictive value was 97% and the negative predictive value was 100%. The Bland-Altman plot comparing the mean AHI values obtained through PSG and SleepWise shows very good agreement between the two diagnostic techniques, with a bias of -3.85, a standard error of 12.18, and a confidence interval of -0.39 to -7.31. CONCLUSIONS: SleepWise was reasonably accurate for noninvasive and automatic diagnosis of OSA in outpatients. SleepWise determined the severity of OSA with high reliability. The current study including simultaneous laboratory PSG and SleepWise processing image is proposed as a reasonable validation standard.

Treatment with the immunomodulator AM3 improves the health-related quality of life of patients with COPD.

BACKGROUND: COPD has a severe impact on patient quality of life. AM3 is an orally effective immunomodulator that can normalize the defective antimicrobial functions of the immune system effector cells of COPD patients. OBJECTIVES: We analyzed the effect of AM3 on exacerbation frequency and health-related quality of life (HRQL) of COPD patients with moderate disease. DESIGN: A randomized, double-blind, placebo-controlled trial. SETTING: Outpatient departments of 21 hospitals. METHODS: A total of 253 COPD patients with a mean age of 67.7 years (SD, 8.1 years) and mean FEV(1) percentage of predicted of 49.6% (SD, 10.2%) were evaluated. Patients received (orally) either 3 g/d AM3 or a matched placebo for 180 consecutive days. Patient quality of life was measured using the St. George's Respiratory Questionnaire (SGRQ). RESULTS: There were no differences in the exacerbation frequency of the two groups (0.82 episodes per patient in the AM3 arm vs 0.84 in the placebo arm), and 55.3% of patients were exacerbation free in the AM3 arm compared to 48.8% in the placebo arm (p = 0.11). At the end of treatment, quality of life was significantly better in the AM3 arm than in the placebo arm (SGRQ total score, 32.9; SD, 16.4, compared to 37.5; SD, 17.5 [p < 0.05]: activity score, 47.5; SD, 22.4, compared to 54.6; SD, 20.5 [p < 0.05]). The improvements in total SGRQ scores were 8.9 U (SD, 13.4 U) in the AM3 arm and 5.6 U (SD, 15.9 U) in the placebo arm (p = 0.076). Improvements on the symptoms subscale were 15.9 U (SD, 20.7 U) for the AM3 arm and 10.2 U (SD, 21.3 U) for the placebo arm (p < 0.05). Both AM3 and the placebo were clinically, biochemically, and hematologically well tolerated. CONCLUSIONS: AM3 is a safe, easily tolerated, effective treatment that improves the quality of life of COPD patients as measured by SGRQ scores. This effect was observed with no significant reduction in the frequency of exacerbations.

Environmental legionellosis and oropharyngeal colonization by Legionella in immunosuppressed patients.

Inhalation of contaminated aerosols is considered the most common route of Legionella transmission. The aim of this study was to determine whether contact with water contaminated by Legionella was related to oropharyngeal colonization in immunosuppressed patients. Eighty-five oropharyngeal swabs (April 1996 to June 1996) were seeded on selective and nonselective buffered charcoal-yeast extract media. Legionella was not isolated.

Physical activity and its determinants in severe chronic obstructive pulmonary disease.

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) have a limited exercise capacity. Surprisingly, little is known about their levels of physical activity practice. We assessed the levels and determinants of physical activity practice in severe COPD patients. METHODS: A cross-sectional systematic sample of 346 COPD patients was recruited during 1 yr in four tertiary hospitals of the Barcelona area of Spain. Patients answered a questionnaire, which included physical activity assessment, and performed spirometric tests and blood gases. RESULTS: Seventy-eight percent of patients walked daily whereas 17% did not practice any physical activity. Median energy expenditure in physical activity was 109 kcal x d(-1) (IQR 24-239). The following factors were independently associated with a lower physical activity level in a logistic regression analysis: female sex (OR 2.92, 95% CI 1.11-7.70), older age (1.04, 1.01-1.07 per year), higher socioeconomic status (2.23, 1.24-4.02), diabetes (2.66, 1.40-5.06), lower physical and mental quality of life (0.93, 0.90-0.96 and 0.96, 0.93-0.98, respectively, per unit), and long-term oxygen therapy (2.07, 1.19-3.60). Neither FEV1, previous COPD admissions, body mass index, nor other treatments were related to physical activity practice. CONCLUSIONS: In conclusion, one third of severe COPD patients in our study reported a level of physical activity lower than the equivalent to walking less than 15 min x d(-1). Apart from sociodemographic variables, comorbidity, health-related quality of life, and long-term oxygen therapy were the only factors independently associated with a low level of physical activity.