Peak Expiratory Flow Variability Research Articles

Brittle asthma

Brittle asthma is a clinical phenotype of the disease at the severe end of the spectrum. Type 1 brittle asthma is characterised by a maintained wide PEF variability (> 40% diurnal variation for > 50% of the time over a period of at least 150 days) despite considerable medical therapy including a dose of inhaled steroids of at least 1500 pg of beclomethasone or equivalent. Type 2 brittle asthma is characterised by sudden acute attacks occurring in less than three hours without an obvious trigger on a background of apparent normal airway function or well controlled asthma. Mechanisms behind the development of brittle asthma include smooth muscle contraction and edema of the airways, which are supported by chronic airway inflammation. Allergy reactions, impairment of local immunity, respiratory infections, psycho-social disorders and reduced perception of worsening airway function are the risk factors for brittle asthma. The diagnosis is based on the analysis of specific symptoms, role of triggers, personal or family history, measurement of lung function and PEF monitoring. Pharmacological treatment of type 1 brittle asthma in addition to the high doses of inhaled and/or oral steroids and bronchodilators includes subcutaneous injections of beta2 agonist and inhalation of long acting beta2 agonist. The treatment of patients with type 2 brittle asthma includes exclusion of allergen exposure, identification of triggers, self management and management of acute attacks.

Are serum eosinophilic cationic protein levels of toll collectors affected by diesel exhaust exposure?

Objective:There are few studies on the diesel exhaust particulates (DEP) / eosinophilic cationic protein (ECP) level relationship. This study aimed to detect ECP levels in a highly DE exposed group, named as toll collectors.Methods:In a cross-sectional study, levels of serum ECP, rates of respiratory symptoms, mean levels of respiratory functions, smoking status, and variations in peak expiratory flow (PEF) during weekends and working days were compared for 68 toll collectors (TC) (range of age, 24-48 years) and 28 controls (range of age, 25-61 years). All subjects in the study group were men.Results:No significant difference was observed in terms of symptoms and smoking rates between the toll collectors and control group. The number of toll collectors [12/68 (17.7%) vs 1/28 (3.5%)] with diurnal PEF variability in the working period was higher than that of controls (p=0.058). Mean ECP level of toll collectors was higher than that of controls (32.8 vs 21.4 ng/L), but the difference was not significant. Mean ECP levels were higher in subjects experiencing diurnal PEF variability during work and off-work periods (34.9 vs 28.3 ng/L, p=0.410).Conclusions:Serial PEF measurements combined with serum ECP measurements did not add a new tool to detect the sensitivity of workers dealing with DE. Much more diesel exhaust exposed workers should be included to search for cheap and available methods when evaluating airway.

Efficacy of acupuncture in children with asthma: a systematic review.

BackgroundWe performed a systematic review of the efficacy of various types of acupuncture in the treatment of asthma in children.MethodsWe searched the MEDLINE, Embase, and Cochrane Library databases up to October 20, 2014. Randomized controlled trials (RCTs) of children and adolescents (<18 years of age) with asthma were included. Data extraction was applied, and methodologic quality was assessed.ResultsA total of 32 articles were assessed for eligibility, and seven studies comprising 410 patients were included in the systematic review. Two RCTs showed significant improvement in peak expiratory flow (PEF) variability for acupuncture (traditional and laser) vs. control, with one showing significant improvement in asthma-specific anxiety level, but no significant differences in other lung function parameters or quality of life. Another RCT reported significant benefits of laser acupuncture on lung function parameters but did not describe or report statistical analyses. One crossover RCT showed significant improvements in response to both acupuncture and placebo acupuncture, with better improvements with acupuncture compared to placebo acupuncture (forced exhaled volume in 1 s [FEV1], PEF). Two additional crossover RCTs showed no significant differences between single sessions of laser acupuncture and placebo acupuncture on baseline, postacupuncture, and postinduced bronchoconstriction values (% predicted FEV1, maximum expiratory flow). A recent study showed a significant effect of acupuncture paired with acupressure on medication use and symptoms in preschool-age children. Methodologic and reporting variability remains an issue. However, the results suggest that acupuncture may have a beneficial effect on PEF or PEF variability in children with asthma.ConclusionsThe efficacy of acupuncture on other outcome measures is unclear. Large-scale RCTs are needed to further assess the efficacy of acupuncture in the treatment of asthma in children.

Cleaning products and short-term respiratory effects among female cleaners with asthma

ObjectiveWe evaluated the short-term effects of exposure to cleaning products on lung function and respiratory symptoms among professional cleaning women.MethodsTwenty-one women with current asthma and employed as professional cleaners participated...

Change in peak expiratory flow over time among workers exposed to polyvinyl chloride dust.

To evaluate the variation of peak expiratory flow (PEF) over a working week among non-smoking workers without previous asthma who have been exposed to polyvinyl chloride (PVC) dust. We conducted a cross-sectional study among 42 operators with exposure to PVC dust (filling hoppers to feed extrusion machines) and 23 employees without exposure to PVC dust in a plant producing PVC pipes in West Africa. A pre-tested questionnaire was administered and PEF was measured using a portable peak flow meter after a day off (day 1), on day 3 and at the end of the week (day 6). The two groups did not differ by age or body mass index. Dyspnoea was more prevalent in exposed workers than controls (52% vs. 13%, P = 0.002). PEF decreased more significantly in exposed workers than controls (-8% vs. -3% on day 3 and -10% vs. -5% on day 6, both P = 0.004). The duration of exposure did not affect PEF variability in the exposed groups. The decrease of PEF over the working week in workers exposed to PVC dust is consistent with occupational asthma, although standard measures to diagnose occupational asthma were not used. This result reinforces the need to prevent excessive exposure to PVC dust.

Questions and commentary on the article ‘Daily changes of peak expiratory flow and respiratory symptom occurrence around a soy processing factory’

Dear Editor, An interesting article by Heederik D et al. was published in a recent number of Ann Agric Environ Med. (2014, vol. 21, no 1, 5–10) concerning the relationship between, on the one hand, concentration of soy allergens in the proximity of a factory producing soy oil and intensity of respiratory symptoms, daily changes of peak expiratory flow (PEF) and bronchodilator utilization [1]. The authors tested daily changes of PEF, bronchodilator use and respiratory symptoms in two groups of people: those living in the vicinity of the soy oil factory and habitants living in the control area located about 5 km from the factory. They found positive skin prick tests (SPTs) to common allergens among 81% of participants and positive results of SPTs to soy in 11–12% examined people. The authors concluded that sensitization to soy allergen was not increased among the people living in the proximity of the factory; however, the soy-sensitized individuals living in the surroundings of the factory reported more respiratory symptoms, greater bronchodilator utilization, and lower PEF after having been downwind of the factory. Peak expiratory flow measurements, above all, are a useful method of evaluation of asthma control. Daily variability of PEF of more than 20% can be a symptom of pathological bronchial tree hyperresponsiveness (BHR) and bad asthma control [2]. BHR is an individual feature and is not directly correlated with the concentration of aeroallergens. Among people with allergic rhinoconjunctivitis and without bronchial asthma and/or BHR, the daily variability of PEF could be slight and may be comprised in the normal value for healthy people. The authors found positive results of allergic skin prick tests in the majority of participants from both groups (81%). Unfortunately, they did not report the percentage of people with asthma in both groups. This is important information, insofar as, for example, a higher incidence of bronchial asthma and BHR among participants from the study group may have influence on the greater variability of PEF, respiratory symptoms and bronchodilator consumption. Additionally, on the other hand, the lack of people with bronchial asthma in the control group could result in small daily PEF changes, scant other symptoms. It is also worth considering the smoking status of the participants in the statistical analysis. In the study group, the percentage of current smokers was higher than in the control; obviously, tobacco addiction has a significant influence on bronchial hyperresponsiveness and value of spirometric function tests [3].

Impact of close-proximity air pollution on lung function in schoolchildren in the French West Indies

BackgroundHigh levels of asthma prevalence and severity of respiratory symptoms have been found in the Caribbean but little is known about the impact of air pollution in these regions.This study aimed to describe air pollution and measure the associations with child lung function in Guadeloupe (French West Indies).MethodsData from 30 randomly chosen elementary schools (8–13 years old) were obtained using a standardized protocol adapted from the ISAAC2 study. We considered two health outcomes: peak expiratory flow (PEF) before running and the variation in peak expiratory flow (ΔPEF) after running. The associations between pollutants and outcomes were investigated using several air pollution exposure models: i) medium-term exposure to close-proximity pollution both indoor and outdoor for ozone (O3) and nitrogen dioxide (NO2) and ii) short- and medium-term exposure to background pollution for O3, NO2, sulphur dioxide (SO2) and small particulate matter (PM10).ResultsOf 1,463 children, 277 (16%) were found to have asthma. A 1-μg/m3 increase in medium-term exposure to outdoor close-proximity pollution by O3 was associated with a PEF decrease (β = −0.32; 95% CI: −0.61;-0.03). No association was found with NO2 regarding close-proximity pollution. The association between medium-term exposure to background pollution and PEF decrease was stronger in asthmatic children than in non-asthmatic children for O3. No reduction in PEF or ΔPEF was shown with NO2, SO2 and PM10 pollutants but a significant association was found between PM10 and PEF increase.ConclusionsOur results suggest that O3 could have an acute effect on child lung function in the Caribbean even at a low concentration (below the WHO guidelines). Further research in the Caribbean is needed to confirm these findings.

Diurnal Variation in Peak Expiratory Flow and Forced Expiratory Volume.

Diurnal variability in airways has most commonly been reported using peak expiratory flow (PEF) and forced expiratory volume in one second (FEV1). Characteristics of variability in small, mid and large airways caliber are expected to be different but have not been studied. The aim of the study was to assess diurnal variation in small mid and large airways caliber using FEF25, FEF50, FEF75 and FEF25-75 along with PEF and FEV1 in healthy subjects. Spirometry was performed in 161 healthy subjects twice in a day. Diurnal variability in FEF25, FEF50, FEF75, FEF25-75, PEF and FEV1 were determined and compared. It revealed that all parameters exhibit significant diurnal variability. Diurnal variability is highest in large airways and lowest in smaller airways. Proximal airways show greater diurnal variation in their caliber than distal airways as reflected by greater variability in PEF as compared to FEV1.

Assessment of Efficacy and Safety between Two Formulations of Formoterol Fumarate in Adolescents and Adults with Persistent Asthma

Objective: The mandatory replacement of chlorofluorocarbons (CFCs) in pressurized metered dose inhalers (pMDIs) with non ozone depleting propellants such as hydrofluoroalkanes (HFA 134a) requires clinical testing that ensures the reformulated aerosol with HFA is as effective and well tolerated as the original CFC version. In view of this, a multicentre, randomised, parallel-group, double-blind study was conducted to compare the safety and efficacy of formoterol fumarate delivered by a MDI using the hydrofluoroalkane (HFA) 134a propellant (Cipla Ltd) with the CFC formulation (Foradil CFC pMDI, Novartis, UK) in adolescents and adults. Methods: Patients on a stable dose of inhaled corticosteroids with a scope for improvement based on mean morning peak expiratory flow (PEF) and symptoms were randomised to receive formoterol HFA MDI 24 mg twice daily or formoterol CFC MDI 24 mg twice daily for 12 weeks. The primary efficacy variable was the mean morning PEF and secondary variables included FEV1, symptom scores, use of relief medication and safety assessments. Results: The difference between the treatments in the adjusted mean morning PEF (formoterol HFA–formoterol CFC) was -4.68 L/min (95% CI: -13.45, 4.09). The lower limit of the 95% confidence interval was within the pre-defined limit (20 L/min) set for non-inferiority. The results of the secondary endpoints supported the findings of the primary endpoint. The incidences of adverse events (AEs) were similar for both formulations. Conclusion: The results of this study confirm that formoterol HFA pMDI is as effective as formoterol CFC pMDI in adolescents and adults.

Asthma Diagnosis in Spain: Survey of Opinions, Attitudes and Knowledge among Primary Care Physicians

Background: Asthma is frequently misdiagnosed. Peak expiratory flow (PEF) measurement is easy and very useful for asthma diagnosis in primary care. Objectives: The DIANA project aimed to assess the impact of a course on PEF measurement among primary care physicians in Spain. Methods: A 7-item questionnaire was sent to selected primary care physicians (Phase A). Respondents were then invited to take a web-based course on PEF in asthma diagnosis. Finally, the questionnaire was again sent to all physicians (Phase B). Questionnaires also asked for demographical data such as age, sex, speciality, route of access to speciality, and geographical area. A comparative statistical analysis was performed on the results of both questionnaires. An extended analysis was performed later. Answers were analysed by percentages and using McNemar’s test. The planned duration of the project was one year. Results: No statistically significant differences in percentages between the two phases were found for Items 1 (related to asthma diagnosis) and 4 (related to availability and use of PEF meter). However, for Item 2 (related to diagnosis of occupational asthma) differences were significant (p<0.05), with an odds ratio (OR) of 1.50 for those participating in Phase B. Differences were also significant (p<0.05) for those who took the course, with an OR of 1.37. For Item 3 (related to the usefulness of measuring daily variability of PEF), there were also significant differences (p<0.05) between the two phases, with an OR of 1.39. There were also significant differences (p<0.05) for those who took the course, with an OR of 1.53. Conclusions: The first four results of the survey showed that educational intervention may improve knowledge of the usefulness of PEF in asthma diagnosis among primary care physicians. However, the high percentages of correct answers among those who did not take the course merit further investigation.

Increased Day-to-Day Variability of Forced Oscillatory Resistance in Poorly Controlled or Persistent Pediatric Asthma

Pediatric asthma lacks sensitive objective measures for asthma monitoring. The forced oscillation technique (FOT) offers strong feasibility across the pediatric age range, but relationships between FOT parameter day-to-day variability and pediatric asthma severity and control are unknown. Day-to-day variability in FOT respiratory system resistance (Rrs) and respiratory system reactance (Xrs) compared with peak expiratory flow (PEF) were defined in 22 children with asthma (mean ± SD age, 10.4 ± 1.1 years) during a 5-day asthma camp. FOT was performed at 6 Hz in triplicate on each test occasion. Relationships between day-to-day FOT variability (expressed as within-subject SD [SDW] and asthma control and severity (defined according to GINA [Global Initiative for Asthma] recommendations) were explored. For comparison, normal baseline FOT values and variability, measured on two occasions, were defined in a separate cohort of 38 healthy children (age, 9.5 ± 1.0 years). Day-to-day Rrs variability was greater in persistent (n = 16) vs intermittent (n = 6) asthma (mean SDW, 0.69 cm H2O/L/s vs 0.39 cm H2O/L/s; P ≤ .01). Day-to-day Rrs variability was increased in uncontrolled (n = 13) vs partly controlled asthma (n = 9) (mean SDW, 0.75 cm H2O/L/s vs 0.42 cm H2O/L/s; P ≤ .05). PEF variability did not differentiate the groups. Day-to-day variability of Rrs and Xrs but not baseline values were increased in children with asthma vs control children (Rrs mean SDW, 0.61 cm H2O/L/s vs 0.33 cm H2O/L/s [P ≤ .05]; Xrs mean SDW, 0.24 cm H2O/L/s vs 0.15 cm H2O/L/s [P ≤ .05]). Increased day-to-day FOT variability exists in school-aged children with asthma. Day-to-day Rrs variability was associated with asthma severity and asthma control. FOT may be a useful objective monitoring tool in pediatric asthma and warrants further study. Australian and New Zealand Clinical Trials Registry; No.: ACTRN12614000885695; URL: www.anzctr.org.au.

How well are asthma treatment cards filled out in public health centres in Gazeera State, Sudan?

Four public district hospitals offering asthma treatment in Gazeera State, Sudan. Incomplete recording of patient data directly affects the quality of asthma care and the evaluation of asthma management programmes. To assess the completeness of filling out of treatment cards and accuracy of calculating peak expiratory flow (PEF) for confirming diagnosis and grading severity of asthma. Cross-sectional audit of asthma treatment cards from asthma centres, 2006-2012. Of 959 patient cards assessed, completeness ranged from 47% to 98%. Six of 13 variables had an unsatisfactory grade of completeness (<80% complete). Calculated PEF was indicated in 885 (92%) cards, but was correct in only 609 (69%). PEF variability was recorded in 835 (87%) cards, but was correctly calculated in 442 (53%). A scheduled follow-up visit was attended by only 359 (37%) patients, indicating 63% loss to follow-up. Contact telephone numbers were missing from 453 (47%) cards. This is the first study in Africa to assess the data completeness and integrity of asthma patient cards, identifying important shortcomings. This affects quality of management of asthma patients and programme evaluation. Steps to rectify this situation are urgently needed.

P74 ‐ Brittle asthma: a clinical phenotype of severe asthma

The term Brittle Asthma was generally used to describe those patients with sudden, severe attacks, usually out of the blue. Recently the following classification was suggested: type 1 characterized by a maintained wide PEF variability despite medical therapy, and type 2 characterized by sudden acute attacks on a background of apparently normal airway function. Patients who develop sudden-onset near-fatal asthma seem to have massive allergen exposure and emotional distress. Diminished perception of dyspnea and reduced compliance with anti-inflammatory therapy have been associated with fatal or near-fatal events. We are presenting two case reports of two patients admitted to emergency service due to severe asthma attacks. The first, 31 year-old patient with clinical history: allergic rhinoconjunctivitis since the age of 16 and untreated atopic asthma since the age of 20. At the moment of hospitalization he was without conscience, with tachypnea, cyanosis and the following vital signs: temperature 37.4°C, blood pressure 90/60 mmHg, pulse rate 140 bpm. The second, 40 year-old patient, was admitted with cyanosis, breathless and agitated with the following vital signs: temperature 37°C, blood pressure 70/40 mmHg, pulse rate 130 bpm. ABG yielded the following: PO2 87.8 mmHg, PCO2 70.9 mmHg, pH 7.14, BE 8.4. His clinical history was: allergic asthma and rhinoconjunctivitis since the childhood, reappearance of asthma at the age of 22, and frequent avoidance of steroid therapy. At the thoracic examination diffuse inspiratory and expiratory wheezes with prolonged expiratoy phase were present. Chest radiography and EKG were normal. Laboratory: blood count, renal, liver functions were normal. They were successfully resuscitated and recovered completely after aggressive treatment. We considered our patients as type 2 brittle asthma. Poor adherence with steroid treatment, ignoring the symptoms of airways obstruction, and emotional distress are offending factors for these near fatal attacks. Patients with brittle asthma are difficult to manage. They have to be monitored firmly and treat the acute attacks with self-administered subcutaneous adrenaline.

Eosinophilic Bronchial Disorders Presenting Chronic Cough; Atopic Cough, Cough Variant Asthma and Non-Asthmatic Eosinophilic Bronchitis

Chronic persistent non-productive cough is troublesome, whereas productive cough is physiologic and acts to remove abnormal secretions and foreign bodies from the lower respiratory tract. Atopic cough is a new clinical entity for bronchodilator-resistant non-productive cough associated with generalized atopy. Pathological characteristics of atopic cough included trachea bronchitis without Broncho Alveolar Lavage (BAL) eosinophilia, and the physiological characteristics included hypersensitivity of the cough reflex without bronchial hyper reactivity. Patients with atopic cough have eosinophilia of the nebulized hypertonic saline-induced sputum but normal spirometry findings and no variability of Peak Expiratory Flow (PEF). These features of atopic cough are distinct from those of cough variant asthma, since these patients have mild bronchial hyper reactivity and eosinophilic inflammation of the central and peripheral airways and their cough is responsive to bronchodilator treatment. Moreover cough-variant asthma is a precursor of typical asthma, while atopic cough is not, because nearly 30% of patients with cough-variant asthma eventually develop typical asthma but patients with atopic cough do not. Although nearly 60% of patients with atopic cough can be successfully treated with histamine H1-receptor antagonists, but other still require additional corticosteroid therapy because bronchoscopic study indicate that bronchial eosinophilic inflammation is more severe in the H1-receptor antagonist-resistant group. Further investigations are required for the clinical entity of eosinophilic bronchitis without asthma, since it seems to resemble to atopic cough and there seems to be considerable overlap of these two clinical entities.

Combination therapy versus monotherapy for gastroesophageal reflux in children with difficult-to-treat bronchial asthma

Gastroesophageal reflux (GER) is a common disorder in children with bronchial asthma. It has been identified as a potential trigger, complication and even differential diagnosis for asthma. Our aim was to find out the efficacy of the combined use of both the proton pump inhibitor esomeprazole and the antidopaminergic prokinetic domperidone versus the sole use of esomeprazole in improving asthma severity in children with difficult to treat asthma. Patients and methodsAmong 178 children with difficult-to-treat asthma, GER was assessed using upper GIT endoscopy. Those who had GER were randomly divided into 2 equal subgroups the first was treated with esomeprazole for 12weeks while the other was treated with esomeprazole and domperidone for the same period (beside the usual treatment for asthma in both groups). Childhood-asthma control test (C-ACT), forced expiratory volume in 1st second (FEV1) [% of predicted], peak expiratory flow (PEF) variability, induced sputum substance P (SP) and endoscopic reflux score (ERS) were recorded before and after the treatment. ResultsGastro-esophageal reflux (GER) was observed in about 45% of children with difficult-to-treat asthma. The C-ACT, induced sputum SP, ERS and FEV1 showed significant improvement while PEF variability showed no significant changes when comparing combination therapy subgroup (esomeprazole and domperidone) with esomeprazole only subgroup. ConclusionsCombination of domperidone and esomeprazole was more effective in improving the endoscopic reflux score, childhood-asthma control test (C-ACT) and FEV1 (% of predicted) and significantly reduced the sputum SP than the use of esomeprazole only in children with difficult-to-treat asthma.

Statistical Model to Study the Effect of Agriculture Crop Residue Burning on Healthy Subjects

Pulmonary function test (PFT) values of 50 healthy subjects and levels of pollutants like suspended particulate matter (SPM), PM10, PM2.5 in ambient air were continually investigated from February 2007 to January 2010 at Patiala, Punjab (India). Significant decrease in PFTs were observed with increase in concentration levels of pollutants during wheat and rice crop residue burning in the fields. In the present paper a new statistical model on field crop residue burning and PFT has been proposed. The model is based on multiple ordinary least square regression method. It can predict values of PFTs as a function of some parameters of air pollutants. Monthly average values of different variables are used for the purpose of designing four different models. These models were tested by parameters like randomness of residual, relationship of residual with independent variables, etc. The final accepted models could predict up to 88 % variation in the values of force vital capacity and force expiratory volume and up to 77 % variation in peak expiratory flow and force expiratory flow with the corresponding changes in the SPM, PM10, PM2.5 and temperature respectively. This model can be used as a tool for measurement of risk assessment due to air pollution in future.

262 Short-term lung function effects after occupational exposure to cleaning products

ObjectiveTo evaluate the acute effects of exposure to cleaning products on lung function of female cleaning workers.MethodsA panel study including 21 female cleaners with persistent asthma symptoms was nested within...

Long-term Mortality among Adults with Asthma: A 25-Year Follow-up of 1,075 Outpatients with Asthma: Ali Z, Dirks CG, Ulrik CS. Chest 2013;143:1649–55.

This prospective case-control study from Denmark recruited 1075 adult patients with asthma from an outpatient allergy clinic from 1974–1990 (and an equal number of age- and sex-matched controls) and followed their outcomes in terms of five major categories of cause of mortality through the end of 2011. Subjects were included based on typical clinical history, reversibility in forced expiratory volume in 1 s (FEV1) > 15% after administration of standardized doses of inhaled beta agonist or oral corticosteroid, or diurnal variability in peak expiratory flow >20%. Subjects were further stratified as having allergic vs. nonallergic asthma on the basis of total serum immunoglobulin E, history of extrinsic asthma, skin prick tests, radioallergosorbent assays, and bronchial provocation tests. Subject and control mortality outcomes were obtained from the Danish Death Register and Danish National Board of Health, and classified into five categories including status asthmaticus, obstructive lung disease not classified as status asthmaticus, cardiovascular disease, malignant neoplasm, and other causes.

Factor analysis in predominantly severe COPD: Identification of disease heterogeneity by easily measurable characteristics

The clinical and demographic variables defining the heterogeneity of chronic obstructive pulmonary disease (COPD) are unclear. A post-hoc analysis of five randomised studies in patients with a history of previous exacerbations examined the clinical and demographic characteristics describing moderate-to-very-severe COPD. Factor analysis was performed on all continuous baseline demographic and clinical data, without variable selection. Analyses were based on the full cohort and on stratifications by pack-years smoked, smoking status, gender, and comorbidities; patient exacerbation history was analysed in two of the five studies. 6162 COPD patients were evaluated (70% male; 40% current smokers; mean pre-bronchodilator forced expiratory volume in 1 s [FEV1] 35.2% predicted). Baseline clinical and demographic variables loaded differentially on six factors with minimal overlap, explaining 60.4% of the heterogeneity: 1) symptoms (cough, dyspnoea, sleep disturbance), health status, reliever use; 2) pre-bronchodilator FEV1, FEV1/forced vital capacity, morning peak expiratory flow (PEF), body mass index (BMI); 3) blood pressure; 4) age, months since first COPD symptoms; 5) PEF variability; 6) pulse, FEV1 reversibility. Most factors loaded similarly in stratified and exacerbation analyses. BMI loaded with reversibility in females, and with age and months since first COPD symptoms in ex-smokers. Exacerbations loaded to factor 6. Readily available data can explain ≈ 60% of COPD heterogeneity in a large dataset of predominantly severe COPD patients. Factors were robust over determinants of disease outcome; gender, smoking status, pack-years smoked, and comorbidities. The main factors were largely unchanged by adding exacerbations. Only BMI loaded to other factors.

Domiciliary diurnal variation of exhaled nitric oxide fraction for asthma control

A major goal of asthma management is maintaining optimal control. Current assessment is based on symptoms and lung function. We evaluated whether domiciliary daily home exhaled nitric oxide fraction (FeNO) monitoring could be useful as an index of asthma control. 50 asthmatic subjects and 15 healthy volunteers with a range of asthma severity underwent asthma control questionnaire (ACQ), spirometry before and after salbutamol and sputum induction. FeNO and peak expiratory flow (PEF) were measured twice daily for 2 weeks. A record of exacerbations was obtained 3 months later. Diurnal FeNO variation in uncontrolled asthmatics was significantly greater than in controlled asthmatics (p<0.01). PEF variation was not different. The daily variation of FeNO levels was also greater in uncontrolled asthmatics compared with controlled asthmatic and healthy subjects (p<0.01). 80% of uncontrolled asthmatics experienced at least one or more exacerbations over the 3 months after the enrolment. The combination of diurnal FeNO variation ≥ 16.6% and ACQ scores ≥ 1.8 was best at predicting uncontrolled asthma (area under curve 0.91, 95% CI 0.86-0.97; p<0.001). Diurnal variation in FeNO can be used as a biomarker of asthma control and as a predictor of the risk of future exacerbation. Prospective studies are warranted.