Peak Expiratory Flow Variability Research Articles

Pulmonary testing using peak flow meters of very low birth weight children born in the perisurfactant era and school controls at age 10 years

We determined lung function at age 10 years in very low birthweight (VLBW, <or=1,500 g) children and controls, and compared the sensitivity to detect subgroup differences by peak expiratory flow (PEF), forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and their diurnal variation. VLBW children were recruited across the perisurfactant era at admission to six NICUs in Wisconsin and Iowa, and controls from area classrooms. Two hundred sixty five VLBW children and 360 controls were tested by the Jaeger AM1 peak flow meter at age 10 years. Two hundred six VLBW and 79 controls had additional home monitoring. Abnormality was defined as observed/predicted ratio <0.8 for PEF, FEV(1), and FVC, and by criteria of Pelkonen for diurnal PEF variation. VLBW children were compared to controls, VLBW children with bronchopulmonary dysplasia (BPD) to those without, and those with respiratory conditions to those without. PEF and FEV(1) showed high reproducibility (intraclass correlations, ICC 0.75-0.83). Controls and VLBW children with and without BPD differed significantly on all measures. Baseline test results did not differ across birth years, but PEF variation was less after surfactant availability (P = 0.04). Observed over predicted FEV(1) was the most sensitive in detecting differences between groups (P < 0.001), with mean (s.d.) 0.97 (0.12) for controls, 0.88 (0.14) for VLBW children without BPD, and 0.78 (0.13) for those with BPD. Odds ratios for abnormality were especially high with respiratory medication use during the first 5 years of life, 4.4 (95% CI: 2.0-9.8) for FEV(1) and 5.1 (95% CI: 2.0-13.2) for diurnal PEF variation. Our results show that respiratory abnormalities persist to at least age 10 years for VLBW children born in the surfactant era.

Relationships of methacholine and AMP responsiveness with peak expiratory flow variability in children with asthma

Both bronchial responsiveness (BR) and peak expiratory flow (PEF) variability are increased in asthma. PEF variability is presumed to reflect the degree of BR in asthma. BR is commonly assessed by bronchial challenges using direct or indirect stimuli. The aim of this study was to compare methacholine and adenosine 5'-monophosphate (AMP) responsiveness with regard to their relationships with PEF variability in children with asthma. Methacholine and AMP challenge tests were performed in 79 children with mild to moderate asthma, and a provocative concentration causing a 20% decline in forced expiratory volume in 1 s (PC(20)) was calculated for each challenge. Subjects recorded PEF each morning and each evening for 14 consecutive days. PEF variability was expressed as amplitude percentage mean (amp%mean; high PEF minus low PEF on each day, expressed as a percentage of their mean, averaged over 14 days), and as the lowest percentage highest (low%high; the lowest PEF expressed as a percentage of the highest PEF recorded over the period). Methacholine PC(20) correlated significantly but weakly with both indices of PEF variability (amp%mean: r=-0.285, P=0.011; low%high: r=0.238, P=0.034). However, there was a significant and strong correlation between AMP PC(20) and both amp%mean (r=-0.583, P=0.000) and low%high (r=0.496, P=0.000). For AMP PC(20), the correlations were stronger than for methacholine PC(20) (comparison of correlation coefficients with amp%mean: P=0.021; with low%high: P=0.063). Both methacholine PC(20) and AMP PC(20) correlated significantly with PEF variability. However, the stronger correlations for AMP PC(20) than for methacholine PC(20) suggest that PEF variability may be better reflected by BR assessed by AMP than by methacholine.

Targeting pCO2 in Asthma: Pilot Evaluation of a Capnometry-Assisted Breathing Training

This pilot study aimed to evaluate the feasibility and potential benefits of a novel biofeedback breathing training for achieving sustained increases in pCO(2) levels. Twelve asthma patients were randomly assigned to an immediate 4-week treatment group or waiting list control. Patients were instructed to modify their respiration in order to change levels of end-tidal pCO(2) using a hand-held capnometer. Treatment outcome was assessed in frequency and distress of symptoms, asthma control, lung function, and variability of peak expiratory flow (PEF). We found stable increases in pCO(2) and reductions in respiration rate during treatment and 2-month follow-up. Mean pCO(2) levels rose from a hypocapnic to a normocapnic range at follow-up. Frequency and distress of symptoms was reduced and reported asthma control increased. In addition, mean PEF variability decreased significantly in the treatment group. Our pilot intervention provided evidence for the feasibility of pCO(2)-biofeedback training in asthma patients.

Short-term variability of airway caliber—a marker of asthma?

Variability in airway caliber is a characteristic feature of asthma. Previous studies reported that the variability in respiratory system impedance (Zrs), measured by the forced oscillation technique during several minutes of tidal breathing, is increased in asthma and may be a marker of inherent instability of the airways. The aims of this study were to determine if short-term variability in impedance correlates with peak expiratory flow (PEF) variability or airway hyperresponsiveness (AHR). The SD of log-transformed impedance (lnZrsSD) was measured as a marker of short-term variability and compared with the diurnal variability of PEF over 2 wk in 28 asthmatic and 7 nonasthmatic subjects and with AHR to histamine in a cohort of 17 asthmatic and 82 nonasthmatic subjects. In addition, lnZrsSD was measured in eight nonasthmatic subjects before and after methacholine challenge in the upright and supine positions. There were no significant differences in lnZrsSD between asthmatic and nonasthmatic subjects (P = 0.68). Furthermore, in asthmatic subjects, lnZrsSD did not correlate with diurnal variability of PEF (rs = -0.12 P = 0.54) or with AHR to histamine (r = 0.10, P = 0.71). Neither methacholine challenge nor supine posture caused any significant change in lnZrsSD. We conclude that our findings do not support previous reports about the utility of short-term variability of impedance. Our findings suggest that, using standard methods for forced oscillometry, impedance variability does not provide clinically useful information about the severity of asthma.

Peak Expiratory Flow Is Not a Quality Indicator for Spirometry: Peak Expiratory Flow Variability and FEV1 Are Poorly Correlated in an Elderly Population

Peak forced expiratory flow (PEF) and FEV(1) are spirometry measures used in diagnosing and monitoring lung diseases. We tested the premise that within-test variability in PEF is associated with corresponding variability in FEV(1) during a single test session. A total of 2,464 healthy adults from the Health, Aging, and Body Composition Study whose spirometry results met American Thoracic Society acceptability criteria were screened and analyzed. The three "best" test results (highest sum of FVC and FEV(1)) were selected for each subject. For those with acceptable spirometry results, two groups were created: group 1, normal FEV(1)/FVC ratio; group 2, reduced FEV(1)/FVC ratio. For each subject, the difference between the highest and lowest PEF (DeltaPEF) and the associated difference between the highest and lowest FEV(1) (DeltaFEV(1)) were calculated. Regression analysis was performed using the largest PEF and best FEV(1), and the percentage of DeltaPEF (%DeltaPEF) and percentage of DeltaFEV(1) (%DeltaFEV(1)) were calculated in both groups. Regression analysis for group 1 and group 2 showed an insignificant association between %DeltaPEF and %DeltaFEV(1) (r(2) = 0.0001, p = 0.59, and r(2) = 0.040, p = 0.15, respectively). For both groups, a 29% DeltaPEF was associated with a 1% DeltaFEV(1). Within a single spirometry test session, %DeltaPEF and %DeltaFEV(1) contain independent information. PEF has a higher degree of intrinsic variability than FEV(1). Changes in PEF do not have a significant effect on FEV(1). Spirometry maneuvers should not be excluded based on peak flow variability.

Is There Any Point in a Corticosteroid Treatment of Intermittent Asthma?

International guidelines advocate the early introduction of inhaled corticosteroids (ICS) in all types of persistent asthma. Our study was undertaken to assess the effects of ICS on bronchial hyperresponsiveness (BHR) as a hallmark of inflammation, and to assess the symptoms, the use of rescue medications, and the parameters of lung function in patients with mild intermittent asthma. The patients with intermittent asthma (n = 85) were randomly allocated to a treatment with ICS, beclomethasone dipropionate 250 μg/day and short-acting β2 agonists salbutamol as needed (Group A, n = 45) or to a treatment with only short-acting β2 agonists as needed (Group B, n = 40) during the 6-month treatment period. At the end of the study, in Group A, we found a statistically significant decrease of BHR (PD20 0.98 vs. 2.07) (p < 0.001), diurnal peak expiratory flow (PEF) variability (17.9 vs. 13.8) (p < 0.001), symptom scores (0.63 vs. 0.30) (p < 0.001), and used rescue medication (p < 0.001), while the parameters of lung function remained unchanged except for forced expiratory volume in 1 sec (FEV1), which had a statistically significant increase (3.58 vs. 3.66) (p < 0.001). In Group B, there was a statistically significant decrease of lung function parameters FEV1 (3.80 vs. 3.71) (p < 0.001), forced vital capacity (FVC) (4.43 vs. 4.37) (p < 0.001), FEV1/FVC (88.2 vs. 85.3) (p < 0.05), PEF (8.05 vs. 7.51) (p < 0.01), PEF variability (17.85 vs. 18.33) (p < 0.001), increased BHR (PD20 1.04 vs. 0.62) (p < 0.05), and symptom scores (0.46 vs. 0.62) (p < 0.01), as well as the use of rescue medication during the day (p < 0.001). Early introduction of low doses of ICS may be more beneficial than β2 agonists alone in patients with intermittent asthma.

Variability in Peak Expiratory Flow Does Not Classify Asthma According to Severity

The aim of this study was to determine whether variability in peak expiratory flow (PEF) could be used to classify the level of severity of asthma in children. We studied 387 boys and girls diagnosed with asthma and classified severity according to clinical criteria (Spanish Society of Pediatric Pneumology). PEF variability was determined using a portable mini-Wright peak flow meter (Clement Clarke International, London, UK; range, 50 L/min-800 L/min) over a 14-day period, with no changes in normal treatment. The following indices were used to calculate PEF variability: 1) difference between morning PEF and nighttime PEF, expressed as a percentage of the mean value of the PEF measurements taken on that day; 2) minimum PEF rate during a week, expressed as a percentage of the highest value recorded during that week; 3) difference between the highest and the lowest PEF values, expressed as a percentage of the highest value; and 4) the 10th percentile of PEF values recorded during a week, expressed as a percentage of the highest value recorded during that week. We assessed agreement between clinical classification and PEF variability using the weighted kappa coefficient. We also analyzed the sensitivity and specificity of PEF variability indices for episodic and persistent asthma. The analysis of levels of agreement between clinical classification of asthma and formulas 1, 2, 3, and 4 gave quadratic weighted kappa coefficients of 0.494, 0, 0.488, and 0.346, respectively. The results were similar when patients were grouped and analyzed by type of asthma (episodic or persistent asthma). The monitoring of PEF variability, a recommendation common in national and international guidelines on the management of asthma in children, is not valid for classifying severity of asthma in children.

Diurnal Variability of Lung Function and Its Association with Sleep among Patients with Asthma

This prospective exploratory story examined diurnal variations in pulmonary function and their association with sleep and quality of life (QOL) in 20 adult asthmatics. Peak expiratory flow (PEF) was assessed for 7 days, before bedtime and upon awakening. There was no association between PEF variability and QOL. Six of 13 polysomnographic measures were significantly correlated with overnight decline in PEF. Individuals with greatest decline took longer to fall asleep and enter Stage 1 sleep, spent less time asleep, and experienced poorer sleep efficiency. Diurnal variations in PEF reflect adverse sleep quality, yet impact on QOL is often unnoticed.

Early MR imaging and spectroscopy appearance of eIF2B-related leukoencephalopathy

Interleukin (IL)-4, IL-5 and interferon (IFN)-gamma are thought to play an important role in chronic airway inflammation in asthmatic subjects. Increased airways responsiveness and nocturnal airway obstruction are important clinical manifestations of asthma. The aim of this study was to investigate whether IL-4, IL-5 and IFN-gamma values are elevated in atopic asthma and correlate with its clinical manifestations. Serum IL-4, IL-5 and IFN-gamma levels of 17 atopic asthmatics and eight nonatopic healthy subjects were determined at 16:00 and 04:00 h by a chemiluminescence enzyme-linked immunosorbent assay (ELISA) method. The clinical manifestation of asthma was determined by assessment of the degree of airway obstruction, airways responsiveness to methacholine and severity of nocturnal airway obstruction, defined as the mean circadian (16:00-04:00 h) peak expiratory flow (PEF) variation. Serum IL-4, IL-5 and IFN-gamma levels were significantly higher in asthmatic subjects as compared to healthy controls, both at 16:00 and 04:00 h. In asthmatic subjects serum IFN-gamma at both time points correlated significantly with the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in one second (PC20,meth) (rho= - 0.55) and with the mean 16:00-04:00 h PEF variation (rho = 0.53). In contrast, no relationship was found between the levels of IL-4 and IL-5 and the parameters of clinical manifestation of asthma. The results suggest that the serum interferon-gamma level is a reflection of the severity of airway inflammation in atopic asthma. More studies are needed to detect the cellular sources and to clarify the exact roles of interferon-gamma and other pro-inflammatory cytokines in asthma.

Asthma, COPD and bronchitis are just components of airway disease

Diseases of the airways of the lungs are common and include asthma, chronic obstructive pulmonary disease (COPD) and bronchitis, as well as emphysema and bronchiectasis. Their diagnosis is often inaccurate because appropriate measurements are not made 1–3 and the definition of airway disease is still imprecise. For example, the Global Initiative for Asthma (GINA) definition of asthma describes components but fails to give a primary definition which distinguishes the disease from others 4. The Canadian definition of COPD includes partly reversible airflow limitation, which is what many would define as asthma 5. Therefore, it seems appropriate to reconsider how we diagnose and define airway disease; this is important in order to optimise treatment. The components (characteristics, features, etc. ) of airway disease include symptoms, variable airflow limitation, airway hyperresponsiveness, chronic airflow limitation and airway inflammation, as well as emphysema and bronchiectasis (fig. 1⇓). They can exist in various combinations. Airway inflammation is central to all other components. It is a cause of symptoms, variable airflow limitation through release of bronchoconstrictor mediators, and chronic airflow limitation through remodelling with structural changes. It also increases airway responsiveness. These components correlate poorly with one another 6–9. The best correlation is between the diurnal variation of peak expiratory flow (PEF) and airway responsiveness 10, which is not surprising since the latter is an important determinant of the former. Symptoms of chest tightness, wheezing, dyspnoea, cough and sputum are all nonspecific since they can result from each of the other components, as well as other respiratory and nonrespiratory conditions. Hence, measurements are needed to be certain as to what the symptoms are associated with. Fig. 1— Relationships between components of airway diseases. Airway inflammation influences all other components, including emphysema and bronchiectasis, which are not shown. Airway hyperresponsiveness is an …

Effect of Fetal Sex on Airway Lability in Pregnant Women With Asthma

An estimated 4% to 8% of pregnant women in the United States have asthma, and there is preliminary (as well as anecdotal) evidence that women bearing a female fetus have more marked symptoms. The authors hypothesized that a female fetus is associated with worse maternal asthma during pregnancy as manifested by greater diurnal variation in peak expiratory flow (PEF)—an accepted marker of the severity of asthma. A protective effect from the androgen surge noted at 12 to 16 weeks gestation when the fetus is male may be part of the explanation. The authors examined this association prospectively in 702 pregnant women diagnosed as asthmatic. They were seen in southern New England in the years 1997–2000. Repeated measurements of expiratory flow lability (percent daily maximum minus the minimum divided by the mean PEF) were made at 21, 29, and 37 weeks gestation. Participants were contacted by phone and asked about symptoms within a month after delivery. The median PEF rate was somewhat higher in women carrying a male rather than a female fetus (378 vs 370 L/minute). Measurements of median diurnal variation in PEF indicated more severe asthma in women bearing a female fetus (8.5% vs 7.8%). In a fully adjusted model, there was a difference of −9.9% in airway lability (95% confidence interval, −19.4 to −0.4) between women carrying a female fetus and those with male fetuses. Greater lability was associated with presence of a female fetus. This difference persisted throughout pregnancy. These findings affirm a correlation between fetal sex and the severity of maternal asthma during pregnancy. Throughout pregnancy, an approximately 10% improvement in airway lability was associated with the presence of a male rather than a female fetus.

Airway cytokine expression measured by means of protein array in exhaled breath condensate: Correlation with physiologic properties in asthmatic patients

Simultaneous monitoring of airway inflammation and physiology might be useful for asthma management. We examined the upregulated molecules in asthmatic airways. Furthermore, we investigated the relationship between these molecules and the airway physiologic properties of asthma. Ten nonsmoking healthy subjects and 16 steroid-naive asthmatic patients were enrolled. Exhaled breath condensate (EBC) sampling, spirometry, and methacholine inhalation challenge were performed on one occasion in this cross-sectional study. Peak expiratory flow was also measured for 4 weeks. Airway cytokine-chemokine-growth factor production was analyzed with a protein array. The expressions of IL-4, IL-8, IL-17, TNF-alpha, RANTES, IFN-gamma-inducible protein 10, TGF-beta, and macrophage inflammatory protein 1alpha and 1beta were significantly upregulated in asthmatic airways compared with those of nonsmoking healthy subjects. Among the upregulated molecules, RANTES expression was significantly correlated with the parameters that represent airway caliber, FEV(1) and respiratory resistance values. In addition, the levels of both TNF-alpha and TGF-beta were significantly correlated with the methacholine threshold and peak expiratory flow variability for the week. Inflammatory molecule analysis with EBC appeared to be useful for monitoring the asthmatic airway condition. Measurements of cytokine levels in EBC might be a promising approach to assess the efficacy of pharmacologic interventions and to investigate the pathophysiology of asthma.

Determinants of the bronchodilation response to salbutamol on histamine-induced bronchoconstriction

Assessment of the bronchodilation response to short-acting beta2-adrenoreceptor agonists on pharmacologically induced bronchoconstriction has often been used to investigate airway smooth muscle beta2-adrenoreceptor function. However, little is known about factors affecting this response. In the present study, the bronchodilation response to 0.2 mg of salbutamol on histamine-induced bronchoconstriction was assessed in 101 steroid-naïve asthmatic subjects. The associations of the response with a wide range of challenge procedure-related variables, clinical asthma severity indicators, and blood markers of airway inflammation were investigated. The response was re-assessed after 6 and 12 weeks' therapy with inhaled budesonide. Baseline FEV1, final histamine concentration, and the maximal fall in FEV1 explained 35-59% of the total variation in the response to salbutamol, depending on the index chosen to express the response. Serum concentration of myeloperoxidase, an index of neutrophilic inflammation, was associated with a poor response. The preceding week daily PEF variation, rescue bronchodilator use, severity of asthmatic symptoms, blood eosinophil count, and serum eosinophilic cationic protein and eosinophilic protein X concentrations were not associated with the response. The salbutamol response seemed to diminish during budesonide treatment but when adjusted by the challenge procedure-related variables the treatment effect vanished. In conclusion, the bronchodilation response to salbutamol on histamine-induced bronchoconstriction is largely determined by challenge procedure-related variables. It seems to be unrelated to the clinical severity of asthma and is not affected by treatment with inhaled corticosteroids. Neutrophilic airway inflammation may be associated with a poor response.

Response profiles to fluticasone and montelukast in mild-to-moderate persistent childhood asthma

Outcome data are needed to base recommendations for controller asthma medication use in school-aged children. We sought to determine intraindividual and interindividual response profiles and predictors of response to an inhaled corticosteroid (ICS) and a leukotriene receptor antagonist (LTRA). An ICS, fluticasone propionate (100 mug twice daily), and an LTRA, montelukast (5-10 mg nightly, age dependent), were administered to children ages 6 to 17 years with mild-to-moderate persistent asthma using only as-needed bronchodilators in a multicenter, double-masked, 2-sequence, 16-week crossover trial. Clinical, pulmonary, and inflammatory responses to these controllers were evaluated. Improvements in most clinical asthma control measures occurred with both controllers. However, clinical outcomes (asthma control days [ACDs], the validated Asthma Control Questionnaire, and albuterol use), pulmonary responses (FEV(1)/forced vital capacity, peak expiratory flow variability, morning peak expiratory flow, and measures of impedance), and inflammatory biomarkers (exhaled nitric oxide [eNO]) improved significantly more with fluticasone than with montelukast treatment. eNO was both a predictor of ACDs (P = .011) and a response indicator (P = .003) in discriminating the difference in ACD response between fluticasone and montelukast. The more favorable clinical, pulmonary, and inflammatory responses to an ICS than to an LTRA provide pediatric-based group evidence to support ICSs as the preferred first-line therapy for mild-to-moderate persistent asthma in children. eNO, as a predictor of response, might help to identify individual children not receiving controller medication who achieve a greater improvement in ACDs with an ICS compared with an LTRA.

Maximal Airway Response to Methacholine in Cough-Variant Asthma: Comparison With Classic Asthma and Its Relationship to Peak Expiratory Flow Variability

<h3>Background:</h3> In asthmatic subjects, not only airway sensitivity but maximal airway response are increased on the dose-response curve to methacholine, and peak expiratory flow (PEF) variability is closely related to airway hypersensitivity and maximal airway response. <h3>Objective:</h3> The aims of this study were to compare the prevalence and the level of maximal response plateau between patients with cough-variant asthma (CVA) and those with classic asthma (CA), and to examine the relationship between airway hypersensitivity or maximal airway response and PEF variability in patients with CVA. <h3>Methods:</h3> A high-dose methacholine inhalation test was performed on 83 patients with CVA and on 83 patients with CA matched for provocative concentration of methacholine causing a 20% fall in FEV₁ (PC₂₀). PEF was recorded in the morning and evening for 14 consecutive days in 78 CVA patients, and the amplitude percentage mean was used to express the diurnal PEF variation. <h3>Results:</h3> Fifty-two CVA subjects (62.7%) but only 33 CA subjects (39.8%) showed a maximal response plateau. This difference was significant after correction by the Bonferroni method (corrected p=0.024). Subjects in the CVA and CA groups showing a plateau had significantly different plateau levels (38.0 ± 5.9% vs 42.9 ± 3.9%, corrected p=1.0 × 10^-4). In patients with CVA, no significant relationship was found between PC₂₀ and PEF variability. However, the absence of a maximal response plateau and a higher plateau level were associated with increased PEF variability. <h3>Conclusions:</h3> Maximal airway response may be an important confounder in the relationship between airway hypersensitivity and the clinical expression of asthma. The identification of a maximal response plateau and the level of this plateau in patients with CVA provide information relevant to PEF variability.

Inhaled fluticasone propionate is effective as well as oral prednisone in reducing sputum eosinophilia during exacerbations of asthma which do not require hospitalization

The aim of this study was to evaluate whether fluticasone propionate (FP) is effective as well as prednisone (P) in reducing sputum eosinophilia and in improving airway obstruction due to asthma exacerbations not requiring hospitalization. We measured, in a parallel-group, double-blind double-dummy, randomized study, sputum and blood inflammatory cell counts and soluble mediators in 37 asthmatic subjects during a spontaneous exacerbation of asthma (Visit 1) and after a 2 week (Visit 2) treatment with inhaled FP (1000 μg bid) (Group A, n = 18 ) or a reducing course of oral P (Group B, n = 19 ). Asthma exacerbation was accompanied by sputum eosinophilia (eosinophils >2%) in almost all patients (95%). FP improved FEV 1 (from 53.9%±16.8 at Visit 1 to 76.4%±21.2 at Visit 2, p = 0.0001 ) and reduced the percentage of sputum eosinophils (from 38%[0–78] to 3%[1–31, p = 0.0008 ) as well as oral P (FEV 1: from 51.5%±14.4 to 83.6%±21.1, p = 0.0001 ; sputum eosinophils: from 52%[1–96] to 11%[0–64], p = 0.0003 ). At Visit 2, sputum eosinophils were significantly lower in Group A than in Group B. P but not FP induced significant decrease in blood and sputum ECP. Oxygen saturation, PEF variability, symptom score and use of rescue medication similarly improved in both groups. We conclude that FP is effective at least as well as P in reducing sputum eosinophilia and in improving airway obstruction due to asthma exacerbation. However, the cost/effectiveness ratio of this option should be further evaluated.

Effects of ambient particulate matter on peak expiratory flow rates and respiratory symptoms of asthmatics during Asian dust periods in Korea

Dust generating events frequently produce ambient dust particles that are less than 10 microm in diameter, and these have been linked to adverse effects in the general population. However, the evidence linking these particles to adverse effects on the airways of asthmatic individuals is limited. The objective of this study was to investigate the possible adverse effects of Asian dust events on the respiratory functions and symptoms of subjects with bronchial asthma. From March to June 2002, individuals were enrolled who had been diagnosed as having asthma by bronchial challenge or by their bronchodilator response. The patients were divided into three groups according to asthma severity: mild, moderate and severe. Patients with other major disease states were excluded. Patients completed twice-daily diaries monitoring PEF, respiratory symptoms, and daily activities. The daily and hourly mean levels of particulate matter <10 microm in diameter (PM(10)), as well as nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)), ozone (O(3)) and carbon monoxide (CO) were measured at 10 monitoring sites in Incheon, Korea. Dust events occurred 14 times during the study period. On dusty days there were increased levels of PM(10), decreased levels of NO(2) and SO(2), and no change in the CO levels, compared to the levels on control days. An increase in PM(10) concentration was associated with increases in PEF variability of >20% (P<0.05), more night-time symptoms (P<0.05), and a decrease in the mean PEF (P<0.05), calculated by longitudinal data analysis. In contrast, there was no association between the PM(10) levels and bronchodilator inhaler use or daytime respiratory symptoms. Using a general additive Poisson regression model, a borderline association was noted between PM(10) and respiratory symptoms, with a relative risk of 1.05 (95% confidence interval (CI), 0.99--1.17). There was no association between the PM(10) concentrations and PEF measurements, with PEF variability of >20% between the morning and evening values and a relative risk of 1.05 (95% CI, 0.89--1.24) in all subjects. This study provides evidence that Asian dust events are impacting on the respiratory symptoms of subjects with bronchial asthma, and ambient air pollution, particularly elevated PM(10), might be one of the aggravating factors.

Do we need to check for asthma in subjects with allergic rhinitis?

-

Longitudinal changes in patient vs. physician-based outcome measures did not significantly correlate in asthma

Background and Objective Although improving health status is one important aim in managing asthmatic patients, few studies have evaluated their health status longitudinally. Therefore, we examined longitudinal changes in health status of asthma patients, and compared them with changes in physiological measures. Methods Eighty-seven outpatients with stable asthma after 6 months of treatment were recruited. Health status using the Asthma Quality of Life Questionnaire (AQLQ) and the St. George's Respiratory Questionnaire (SGRQ), pulmonary function, peak expiratory flow (PEF) values, and airway hyperresponsiveness (AHR) were evaluated at entry and every year over a 5-year period. Results Using mixed effects models to estimate the slopes, the overall AQLQ score declined statistically at a mean rate of 0.06 units/year ( P = .0091). However, this decline did not reach a clinically significant level at 5 years. The total SGRQ score did not change significantly ( P = .54). Although the forced expiratory volume in 1 sec declined at a mean rate of 53 mL/year, the PEF variability and AHR improved significantly. Conclusion Health status was clinically stable over the 5-year study period in patients with asthma, which contrasted with the changes in the physiological outcome measures. As a patient centered outcome measure, health status should be followed separately.

Work, Unemployment and Life Satisfaction among Patients with Diisocyanate Induced Asthma—A Prospective Study

Occupational asthma has been found to be associated with lowered socio-economic outcomes, an increased unemployment rate and a decreased quality of life. The compensation of occupational diseases is comparatively favourable in Finland. Our aim was to follow-up the working status and life satisfaction of patients with diisocyanate-induced asthma in 245 cases diagnosed during 1976-1992. A questionnaire was sent out on average 10 (3-19) yr after the diagnosis to the surviving 235 patients. The questionnaire was validated by re-examining 91 of them clinically, and with spirometry, histamine challenge test and peak flow surveillance. Of the 213 responding patients, 14% were unemployed, and for 50% of them unemployment was caused by asthma. Unemployment was associated with nocturnal asthma symptoms (OR 10.93; CI 2.69-44.452), increased PEF variability (OR 8.46; CI 1.52-46.97) and with the use of short-acting beta-sympathomimetic medication (p=0.045). Satisfaction with life was associated with present working (OR 3.50; CI 1.73-7.06) and with good condition of asthma as assessed by the use of asthma medication (OR 0.49; CI 0.27-0.89) and objective measurements of the asthma condition, e.g. PEF variability (OR 0.21; CI 0.08-0.59). As a conclusion, unemployment was remarkably low as compared with earlier reports and related to the period of simultaneous economic recession. Unemployment, as well as dissatisfaction with life were associated with poor conditions of asthma. Unemployment was associated with improper asthma care favouring the use of short-acting beta-sympathomimetic medication. Proper follow-up of asthma is essential for minimizing the social complaints of occupational asthma, as well as for enhancing life satisfaction.