Methacholine bronchial provocation test for assessment of bronchial hyperresponsiveness in preschool children.

BACKGROUND: Bronchial hyperresponsiveness (BHR) has not been extensively performed in preschool children, possibly because of the difficulty in cooperating with the tests. We sought to determine the usefulness and safety of methacholine bronchial provocation test (MCh-BPT) for BHR assessment in preschool children. METHODS: We recruited 252 preschool children (190 healthy and 62 with wheezing) who underwent MCh-BPT at baseline. MCh-BPT was re-scheduled in case initial attempts failed. Forced expiratory volumes in 0.5 (FEV0.5), 0.75 (FEV0.75) and one second (FEV1) were measured. We recorded the provocative dose causing 15% (PD15) or 20% reduction (PD20) in FEV0.5, FEV0.75 and FEV1, thus allowing for comparison of the diagnostic value of PD15 and PD20. RESULTS: A total of 209 children [156 (82.1%) healthy, 53 (85.5%) with wheezing] successfully completed MCh-BPT. Compared with healthy children, a significantly greater proportion of children with wheezing had measurable PD15FEV0.5, PD15FEV0.75 and PD15FEV1 (P<0.01), and PD20FEV0.5, PD20FEV0.75 and PD20FEV1 (P<0.05). The sensitivity was 92.5% and 94.3% for PD20FEV1, and PD15FEV1 and the specificity was 93.6% and 93.6% respectively, for discriminating asthmatic from healthy children. CONCLUSIONS: Most preschool children successfully and safely complete MCh-BPT, with higher success rate in larger age group. PD20FEV0.5 and PD20FEV0.75 can be surrogates of PD20FEV1 among children whose expiration lasted for less than one second. PD15 has a good diagnostic value as PD20 for diagnosing of BHR in preschool children, which are also more suitable for children five years old or elder.

Residual volume/total lung capacity ratio confers limited additive significance to lung clearance index for assessment of adults with bronchiectasis.

BACKGROUND: Mosaicism and hyperinflation are common pathophysiologic features of bronchiectasis. The magnitude of ventilation heterogeneity might have been affected by the degree of hyperinflation. Some studies have evaluated the discriminative performance of lung clearance index (LCI) in bronchiectasis patients, but the additive diagnostic value of hyperinflation metrics to LCI is unknown. OBJECTIVE: To compare LCI and the ratio of residual volume to total lung capacity (RV/TLC), along with the LCI normalized with RV/TLC, in terms of discriminative performance, correlation and concordance with clinical variables in adults with bronchiectasis. METHODS: Measurement items included chest high-resolution computed tomography, multiple-breath nitrogen washout test, spirometry, and sputum culture. We analyzed bronchodilator responses by stratifying LCI and RV/TLC according to their median levels (LCIHigh/RV/TLCHigh, LCILow/RV/TLCHigh, LCIHigh/RV/TLCLow, and LCILow/RV/TLCLow). RESULTS: Data from 127 adults with clinically stable bronchiectasis were analyzed. LCI had greater diagnostic value than RV/TLC in discriminating moderate-to-severe from mild bronchiectasis, had greater concordance in reflecting clinical characteristics (including the number of bronchiectatic lobes, radiological severity score, and the presence of cystic bronchiectasis). Normalization of LCI with RV/TLC did not contribute to greater discriminative performance or concordance with clinical variables. The LCI, before and after normalization with RV/TLC, correlated statistically with age, sex, HRCT score, Pseudomonas aeruginosa colonization, cystic bronchiectasis, and ventilation heterogeneity (all P<0.05). Different bronchodilator responses were not significant among the four subgroups of bronchiectasis patients, including those with discordant LCI and RV/TLC levels. CONCLUSION: LCI is superior to RV/TLC for bronchiectasis assessment. Normalization with RV/TLC is not required. Stratification of LCI and RV/TLC is not associated with significantly different bronchodilator responses.

Adenosine monophosphate is not superior to histamine for bronchial provocation test for assessment of asthma control and symptoms.

BACKGROUND: Adenosine monophosphate (AMP) may reflect airway inflammation and hyperresponsiveness, but relationship between AMP and histamine (His, a conventional stimulus) bronchial provocation test (BPT) in asthma is not fully elucidated. OBJECTIVES: To compare both BPTs and determine their utility in reflecting changes of asthmatic symptoms. METHODS: BPTs were performed in a cross-over fashion, at 2-4 day intervals. Cumulative doses eliciting 20% FEV1 fall (PD20 FEV1 ), diagnostic performance and adverse events (AEs) were compared. Patients with PD20 FEV1 lower than geometric mean were defined as responders, otherwise poor responders. Patients with uncontrolled and partly controlled asthma, who maintained their original inhaled corticosteroids therapy, underwent reassessment of airway responsiveness and asthmatic symptoms 3 and 6 months after. RESULTS: Nineteen uncontrolled, 22 partly controlled and 19 controlled asthmatic patients and 24 healthy subjects were recruited. Lower PD20 FEV1 geometric means were associated with poorer asthma control in His-BPT (0.424 µmol vs 1.684 µmol vs 3.757 µmol), but not AMP-BPT (11.810 µmol vs 7.781 µmol vs 10.220 µmol). Both BPTs yielded similar overall diagnostic performance in asthma (area under curve: 0.842 in AMP-BPT vs 0.850 in His-BPT). AEs, including wheezing and tachypnea, were similar and mild. Ten patients with uncontrolled and 10 partly controlled asthma were followed-up. At months 3 and 6, we documented an increase in PD20 FEV1 -AMP and PD20 FEV1 -His, which did not correlate with reduction asthmatic symptom scores. This overall applied in responders and poor responders of AMP-BPT and His-BPT. CONCLUSION: Despite higher screening capacity of well-controlled asthma, AMP-BPT confers similar diagnostic performance and safety with His-BPT. AMP-BPT might not preferentially reflect changes asthmatic symptoms.

Impact of air pollution on the burden of chronic respiratory diseases in China: time for urgent action.

In China, where air pollution has become a major threat to public health, public awareness of the detrimental effects of air pollution on respiratory health is increasing-particularly in relation to haze days. Air pollutant emission levels in China remain substantially higher than are those in developed countries. Moreover, industry, traffic, and household biomass combustion have become major sources of air pollutant emissions, with substantial spatial and temporal variations. In this Review, we focus on the major constituents of air pollutants and their impacts on chronic respiratory diseases. We highlight targets for interventions and recommendations for pollution reduction through industrial upgrading, vehicle and fuel renovation, improvements in public transportation, lowering of personal exposure, mitigation of the direct effects of air pollution through healthy city development, intervention at population-based level (systematic health education, intensive and individualised intervention, pre-emptive measures, and rehabilitation), and improvement in air quality. The implementation of a national environmental protection policy has become urgent.

Maximal mid-expiratory flow is a surrogate marker of lung clearance index for assessment of adults with bronchiectasis.

Little is known about the comparative diagnostic value of lung clearance index (LCI) and maximal mid-expiratory flow (MMEF) in bronchiectasis. We compared the diagnostic performance, correlation and concordance with clinical variables, and changes of LCI and MMEF% predicted during bronchiectasis exacerbations (BEs). Patients with stable bronchiectasis underwent history inquiry, chest high-resolution computed tomography (HRCT), multiple-breath nitrogen wash-out test, spirometry and sputum culture. Patients who experienced BEs underwent these measurements during onset of BEs and 1 week following antibiotics therapy. Sensitivity analyses were performed in mild, moderate and severe bronchiectasis. We recruited 110 bronchiectasis patients between March 2014 and September 2015. LCI demonstrated similar diagnostic value with MMEF% predicted in discriminating moderate-to-severe from mild bronchiectasis. LCI negatively correlated with MMEF% predicted. Both parameters had similar concordance in reflecting clinical characteristics of bronchiectasis and correlated significantly with forced expiratory flow in one second, age, HRCT score, Pseudomonas aeruginosa colonization, cystic bronchiectasis, ventilation heterogeneity and bilateral bronchiectasis. In exacerbation cohort (n = 22), changes in LCI and MMEF% predicted were equally minimal during BEs and following antibiotics therapy. In sensitivity analyses, both parameters had similar diagnostic value and correlation with clinical variables. MMEF% predicted is a surrogate of LCI for assessing bronchiectasis severity.

Quality Assessment of Clinical Practice Guidelines for Respiratory Diseases in China: A Systematic Appraisal.

BACKGROUND: There has been a significant increase in the publication of clinical practice guidelines (CPGs) for respiratory diseases in China. However, little is known about the quality and potential impacts of these CPGs. Our objective was to critically evaluate the quality of Chinese CPGs for respiratory diseases that were published in peer-reviewed medical journals. METHODS: A systematic search of scientific literature published between 1979 and 2013 was undertaken to identify and select CPGs that were related to respiratory diseases. Four Chinese databases (the Chinese Biomedical Literature database [CBM], the China National Knowledge Infrastructure [CNKI], the VIP database, and the WANFANG database) were used. The quality of eligible guidelines was assessed independently by four reviewers using the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. The overall agreement among reviewers was evaluated using an intraclass correlation coefficient. RESULTS: A total of 109 guidelines published in 27 medical journals from 1979 to 2013 were evaluated. The overall agreement among reviewers was considered good (intraclass correlation coefficient, 0.838; 95% CI, 0.812-0.862). The scores of the six AGREE domains were low: 57.3% for scope and purpose (range, 4.2%-80.5%), 23.8% for stakeholder involvement (range, 2.8%-54.2%), 7.7% for rigor of development (range, 0%-27.1%), 59.8% for clarity and presentation (range, 22.2%-80.6%), 10.9% for applicability (range, 0%-22.9%), and 0.6% for editorial independence (range, 0%-16.7%). Scores for all guidelines were below 60%, and only three guidelines (2.8%) were recommended for clinical practice with modifications. CONCLUSIONS: The quality of the guidelines was low, and stakeholder involvement, rigor of development, applicability, and editorial independence should be considered in the future development of CPGs for respiratory diseases in China.