Assessing symptoms and peak expiratory flow rate as predictors of asthma exacerbations

OBJECTIVE: To investigate peak expiratory flow rate (PEFR) and quality of life scores for their ability to predict exacerbations of asthma. PARTICIPANTS AND METHODS: We identified adults who received oral or inhaled asthma medications from 36 community drugstores. We administered the McMaster Asthma Quality of Life Questionnaire (AQLQ) and measured PEFR, defining "red zone" (highest risk) as a PEFR < 50% of each patient's expected value based on gender, age, and height. We identified asthma exacerbations (breathing-related emergency department visits and hospitalizations) within 4 and 12 months after enrollment and used proportional hazards regression to assess the ability of PEFR and AQLQ scores to predict exacerbations, controlling for clinical and demographic factors. RESULTS: A red zone PEFR was a significant univariable predictor of exacerbations within 12 months (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.1 to 3.0; P =.027). However, neither a red zone PEFR, the raw PEFR, or percent of predicted maximal PEFR were significantly predictive when controlling for AQLQ scores, clinical characteristics, or demographic data (P >.2). However, the 4 subscales of the AQLQ were each significant univariable and multivariable predictors of asthma exacerbations. For example, the overall AQLQ scale had a multivariable HR of 0.63 (95% CI, 0.46 to 0.87; P =.005) for exacerbations occurring within 4 months and 0.66 (95% CI, 0.54 to 0.82; P <.001) within 12 months. CONCLUSIONS: PEFR added no predictive information to that contained in AQLQ scores and clinical and demographic data. These results support the National Institutes of Health asthma guidelines' recommendation for routinely assessing symptoms but not PEFR.     

The normal range of diurnal changes in peak expiratory flow rates. Relationship to symptoms and respiratory disease

Measuring peak expiratory flow rates (PEFR) several times a day can provide an objective assessment of functional changes relative to environmental or occupational exposures. This report describes the pattern of diurnal changes in PEFR in a reference population, and defines ranges of "normal" between- and within-day variability. An index of diurnal changes was defined as the ratio between maximal and minimal values, where the maximal value was restricted to PEFR measured at noon or in the evening (N, E) and the minimal value was restricted to the morning or at bedtime (M, B). A ratio greater than normal represented an exaggeration of the normal diurnal pattern in PEFR. Normal limits, based on the ninety-fifth percentile in the reference population, were larger for children (130%) than for adults 15 to 35 yr of age (117%) and those older than 35 yr of age (118%). The meaningfulness of excessive diurnal changes in PEFR was examined by relating this ratio (Max/Min), and a similar measure (the amplitude percent mean) to chronic respiratory symptoms and diseases in 938 adults and children who recorded PEFR values 2 to 4 times per day for as long as 14 days. There was a strong relationship of diurnal changes in PEFR that exceed normal limits with physician-confirmed asthma (relative risk of 2.99 with Max/Min), with exertional dyspnea (Grade 2+), and with more frequent reporting of acute symptoms of wheeze, attacks of wheezing dyspnea, cough, and chest colds. In addition, those exceeding the normal limits had about 2.9 times greater risk of having a FEV1 below 80% of predicted, and nearly 7 times greater risk of being below 70%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of respiratory illness on expiratory flow rates in normal,asthmatic, and allergic children

We examined the effects of current respiratory illness (RI) on pulmonary function (PF) in 1,103 subjects who underwent spirometry at schools twice within a 4-month period. Before spirometry, subjects were asked if they had a "cold or other chest illness" during the previous month, and if so, whether they had fully recovered. Those who had not recovered were considered to have an RI.We found that children without RI at their first PF test who reported RI on retest had significantly lower forced expiratory volume in 1 sec (FEV(1)) (-0.8%), peak expiratory flow rate (PEFR) (-2.2%), forced expiratory flow between 25-75% of vital capacity (FEF(25-75)) (-3.5%), and forced expiratory flow at 75% of vital capacity (FEF(75)) (-5.1%) than those without RI on both test and retest. Restriction of subjects to those without a history of doctor-diagnosed asthma did not appreciably change these findings. Children with hay fever had significantly larger RI-associated decreases for FEV(1), FEF(25-75), and FEF(75), but not PEFR, than those without hay fever. Among asthmatic subjects, those with active asthma had larger RI-associated decreases in FEF(25-75) and FEF(75), but not PEFR, than those without asthma. There was limited evidence that small airway losses were greater in children less than 12.5 years old.We conclude that RI in children who are well enough to attend school may reduce expiratory flow rates. These effects are greater for children with active asthma or hay fever than in those without, and may be inversely related to age.     

: Short-term effects of exposure to particulate matter on hospital admissions for asthma and chronic obstructive pulmonary disease

We investigated the effects of particulate matter (PM) factors on hospitalization rates for asthma and chronic obstructive pulmonary disease (COPD).We obtained data on pollutants—PM₁₀, PM_2.5—in Seoul, South Korea. We also investigated data for asthma and COPD exacerbation that required hospitalization from 2006 to 2016. We used a time-stratified case-crossover design and generalized additive models with log transformation to assess adjusted risk, and conditional logistic regression was performed to analyze these data.Our study showed that PM₁₀ and PM_2.5, on different best lag days, were associated with increased risks of COPD or asthma hospitalization. The odds ratios (ORs) for each per-unit increase in PM₁₀ and PM_2.5 were higher in patients with male asthma (PM₁₀: OR, 1.012; 95% confidence interval [CI], 1.008–1.016 and PM_2.5: OR, 1.015; 95% CI, 1008–1.023), preschool asthma (PM₁₀: OR, 1.015; 95% CI, 1.006–1.015 and PM_2.5: OR, 1.015; 95% CI, 1.009–1.024), male COPD (PM₁₀: OR, 1.012; 95% CI, 1.005–1.019 and PM_2.5: OR, 1.013; 95% CI, 1.000–1.026), and senior COPD (PM₁₀: OR, 1.016; 95% CI, 1.008–1.024 and PM_2.5: OR, 1.022; 95% CI, 1.007–1.036).Increasing PM levels increased hospitalizations for asthma and COPD. Additionally, the consequences may be different according to age and sex, and PM_2.5 may have a more significant effect on airway disease patients than PM₁₀.     

Association between daily ambient air pollution and respiratory symptoms in children with asthma and healthy children in western Japan

Objective: In recent years, air pollutant concentrations in Japan have decreased slightly; however, there are growing concerns about the influences of transnational air pollution on respiratory illness. We aimed to clarify the short-term association between the ambient air pollution and respiratory symptoms among children without asthma, children with asthma not using long-term medications (CA-nonLTM), and those using them (CA-LTM). Methods: A total of 138 children attending 2 primary schools and 71 children with asthma regularly visiting cooperating medical institutions were recruited. Study participants measured peak expiratory flow (PEF) twice a day and recorded coughing, nasal symptoms, and medication use in a diary. Predicted associations between daily air pollutant concentrations and respiratory symptoms, and PEF were evaluated using case-crossover and generalized estimate equation models. Results: Changes in %maxPEF per 10 ppb oxidant (Ox) increase in children without asthma, CA-nonLTM, and CA-LTM were ?0.26% (95% CI: ?0.49, ?0.03), ?0.51% (95% CI: ?0.89, ?0.12), and ?0.20% (95% CI: ?0.42, 0.01), respectively. The odds ratios for coughing per 10 ppb Ox increase in the Lag0 model were 1.34 (95% CI: 1.11, 1.60), 1.52 (95% CI: 1.12, 2.07), and 1.06 (95% CI: 0.93, 1.20), respectively. These suggested that the Ox concentration has graded effects on %maxPEF and coughing, in the following descending order, CA-nonLTM, children without asthma, and CA-LTM. The Ox concentration was also positively associated with nasal symptoms in children without asthma and CA-LTM. Conclusion: Our results suggest that using long-term medications to manage asthma may play an important role in preventing exacerbation of respiratory symptoms due to air pollution.     

Effects of traffic-related air pollution on susceptibility to infantile bronchiolitis and childhood asthma: A cohort study in Korea

Objective: This study examined the role of exposure to traffic-related air pollution (TRAP) on susceptibility to asthma in children with past episodes of bronchiolitis. Methods: The baseline data included 2,627 school children aged 6–14 years who had participated in the longitudinal follow-up survey of the Children's Health and Environmental Research of Korea. Lifetime wheezing, past episodes of bronchiolitis, and doctor-diagnosed asthma were evaluated using an International Study of Asthma and Allergies in Childhood questionnaire. We used generalized linear regression with binomial distribution to calculate the relative risk (RR) between TRAP, assessed by proximity to a main road and the total length of roads, and asthma. Results: Compared with the subjects who had less than 100 m of road length within 200-m radius from their home, those with more than 500 m of road length had significantly increased odds for infantile bronchiolitis (adjusted OR [aOR]: 1.57, 95% confidence interval [CI]: 1.01–2.42). Positive exposure-response relationships were found between residential proximity to the main road and asthma (aOR: 1.79, 95% CI: 1.05–3.06; <75 m vs. >700 m from a main road, P for the trend = 0.02). Closer residential proximity to the main road (<75 m) and bronchiolitis combined increased the risks of newly diagnosed asthma (adjusted RR: 3.62, 95% CI: 1.07–12.26) compared with those without bronchiolitis and living ≥ 75 m away from the main road. Conclusions: TRAP appeared to be associated with an increased asthma among children with bronchiolitis, indicating the importance of modifying effects of bronchiolitis in asthma pathogenesis.     

A panel study of airborne particulate matter composition versus concentration: Potential for inflammatory response and impaired pulmonary function in children

Background

The relationship between airborne particulate matter (PM) and pulmonary function in children has not been consistent among studies, potentially owing to differences in the inflammatory response to PM, based on PM types and sources. The objective of this study was to investigate the effect of airborne PM on pulmonary function in schoolchildren and its potential for an inflammatory response.

Progress of ambient air pollution and cardiovascular disease research in Asia

Asian countries are with deteriorating air quality accompanying the rapid economic and social development of the past decades, and the potential health impacts of air pollution have been noticed by researchers in the region. We reviewed the scientific literature on air pollution and cardiovascular diseases (CVD) published by Asian researchers in English since the 1980s to determine whether the findings in Europe and North America can be extrapolated to Asia. Epidemiological studies show that short-term particulate matter pollution is a strong predictor for CVD morbidity and mortality and suggestive on cerebrovascular morbidity and mortality in newly developed countries in Asia. Multicountry epidemiological studies are needed to fully appreciate the extent of air pollution on CVD in Asia, especially less developed Asian countries. New cohort studies should be initiated to improve our understanding of particulate matter's toxicological pathways, long-term exposure effects, and gene-environment interaction on CVD among the Asian population.