吸入式類固醇會加重汙染對氣喘的影響


  【24drs.com】一篇臨床研究的研究者提出警告,吸入式皮質類固醇無法適當地保護空氣汙染嚴重環境的氣喘孩童,實際上還可能惡化汙染物的影響。
  
  作者們發現,長期與短期曝露於汙染時,會降低肺功能且增加呼吸道過度敏感;研究對象是1,003名氣喘孩童,該篇研究比較了budesonide (商品名Pulmicort,AstraZeneca藥廠)以及nedocromil (美國市場已下市)或安慰劑。
  
  荷蘭Groningen大學Despo Ierodiakonou博士等人在線上發表於7月14日過敏及臨床免疫學期刊的一篇文章指出,相較於安慰劑組,接受budesonide或nedocromil的孩童對於一氧化碳(CO)的呼吸道反應更顯著惡化。
  
  共同作者、西雅圖華盛頓大學醫學院過敏科、小兒科臨床教授Paul V. Williams醫師表示,重點是,即使這些孩童使用吸入式皮質類固醇有相對較好的氣喘控制,他們仍然無法完全免於空氣汙染的影響,所以,他們必須注意相關徵兆,而在空氣品質不佳時,或許應限制戶外活動。
  
  Williams醫師表示,這些研究結果的公衛影響是,在空氣汙染嚴重時,無法認為氣喘控制藥物可對氣喘孩童提供適當保護。
  
  研究者探討「Childhood Asthma Management Program (CAMP)」這項研究納入之孩童的短期臭氧、一氧化碳、二氧化氮、二氧化硫曝露程度,他們也探討使用budesonide或nedocromil是否對汙染的影響有保護效果。
  
  他們發現,在使用支氣管擴張劑後、測量1秒用力呼氣量(FEV1)的變化百分比,平均一氧化碳濃度與肺功能降低有關(同一天內的一氧化碳濃度,每四分位範圍內的FEV1變化為-0.33 [95%信賴區間(CI),-0.49至-0.16],一週平均一氧化碳濃度的FEV1變化則是-0.41 [95% CI,-0.62至-0.21])。
  
  同樣地,一氧化碳與用力肺活量(FVC)的減少有關,且與同一天和一週的平均一氧化碳濃度都有關(分別是-0.19 [95% CI,-0.25至-0.07]和-0.25 [95% CI,-0.43至-0.07])。
  
  此外,4個月的一氧化碳平均濃度,也與使用救助吸入劑之前預測FEV1和FVC的百分比衰退有負相關;4個月時的平均一氧化碳和臭氧濃度與FEV1/FVC比率也是負相關(P < .05)。
  
  作者們寫道,相較於安慰劑組,使用budesonide和nedocromil的孩童短期曝露於一氧化碳時的呼吸道反應惡化,這個結果需要後續探討。
  
  共同作者、麻塞諸塞州波士頓布萊根婦女醫院Channing網絡醫學小組Diane R. Gold醫師在新聞稿中表示,這表示使用控制藥物可能無法使氣喘孩童免於汙染的影響,可能實際上會惡化某些汙染物的負面影響。
  
  研究者也發現,4個月的平均二氧化氮濃度與預測使用支氣管擴張劑後的FEV1和FVC百分比降低有關,特別的是,長期曝露於二氧化硫與FEV1降低20%以上有關,另外,使用吸入型皮質類固醇和一氧化碳對於FEV1的影響惡化有關。
  
  Williams醫師表示,對於我們為何會發現這些變化有許多推測,有些人認為,因為使用吸入型皮質類固醇的孩童控制比較好,所以會比較常在戶外遊玩,但是,我們目前沒有任何證據。
  
  資料來源:http://www.24drs.com/
  
  Native link:Inhaled Steroids Exacerbate Pollution's Effect on Asthma

Inhaled Steroids Exacerbate Pollution's Effect on Asthma

By Neil Osterweil
Medscape Medical News

Inhaled corticosteroids cannot adequately protect children with asthma from high levels of air pollution and may actually exacerbate the effects of pollutants, caution investigators in a clinical study.

The authors found that both long-term and short-term exposures to pollution were associated with decreased lung function and increased airway hyperresponsiveness among 1003 children with asthma who were enrolled in a trial comparing budesonide (Pulmicort, AstraZeneca) with nedocromil (which has since been withdrawn from the US market) or placebo.

Significantly, children receiving either budesonide or nedocromil had a more pronounced worsening of airway responsiveness with exposure to carbon monoxide (CO) than the children who were assigned to placebo, report Despo Ierodiakonou, MD, PhD, from the University of Groningen, the Netherlands, and colleagues in an article published online July 14 in the Journal of Clinical Allergy and Immunology.

"The important point is that even though these kids do have relatively well controlled asthma on inhaled corticosteroids, they still aren't totally protected from the effects of air pollution, so they need to pay attention to alerts and perhaps limit outdoor activities when air quality is poor," coauthor Paul V. Williams, MD, clinical professor of pediatrics in the Division of Allergy at the University of Washington School of Medicine in Seattle, told Medscape Medical News.

The public health implications of the finding are that asthma controller medications cannot be assumed to provide adequate protection for children with asthma during days when there is heavy ambient air pollution, Dr Williams said.

The investigators looked at short- and long-term exposures to ozone, CO, nitrogen dioxide, and sulfur dioxide among children enrolled in the Childhood Asthma Management Program (CAMP) trial. They also examined the question of whether use of either budesonide or nedocromil could protect against the effects of pollution.

They found that average CO concentrations were associated with a decline in lung function, as measured by the percentage change in forced expiratory volume for 1 second (FEV1) after use of a bronchodilator (change per interquartile range, ?0.33 [95% confidence interval (CI), ?0.49 to ?0.16] for same-day change in CO concentration and ?0.41 [95% CI, ?0.62 to ?0.21] for 1-week average CO concentration).

Similarly, CO was associated with declines in forced vital capacity (FVC) both on same-day and 1-week average CO concentrations (?0.19 [95% CI, ?0.25 to ?0.07] and ?0.25 [95% CI, ?0.43 to ?0.07], respectively).

In addition, 4-month CO concentration averages were also negatively associated with declines in the percentage of predicted FEV1 and FVC before the use of a rescue inhaler. Both 4-month average CO and ozone concentrations were negatively associated with the FEV1/FVC ratio (P < .05).

"The worsening of [airway responsiveness] with short-term exposure to CO was stronger for children receiving budesonide and nedocromil compared with placebo, a finding that needs further investigation," the authors write.

"This means use of controller medication may not protect asthmatic children from pollutant effects and may actually worsen the negative effects of some pollutants," coauthor Diane R. Gold, MD, MPH, from the Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, Massachusetts, said in a news release.

The investigators also found that 4-month average nitrogen dioxide concentrations were associated with reduced postbronchodilator FEV1 and FVC percentage predicted. In particular, long-term exposures to sulfur dioxide were associated with a 20% or greater decline in FEV1. In addition, the use of an inhaled corticosteroid was associated with a worsening of the effect of CO on FEV1.

"There is a lot of speculation on why we saw some of those changes, and some people thought that because children who use inhaled corticosteroids had better control of their asthma that they spent more time outdoors playing, but we don't really have any evidence for that," Dr Williams told Medscape Medical News.

The study was supported by the National Institutes of Health, the US Environmental Protection Agency, and the International Initiative for Environment and Public Health Cyprus Program of the Harvard School of Public Health. Dr. Williams reported receiving research support from the National Institutes of Health. Dr. Gold disclosed receiving research support from the US Environmental Protection Agency, the National Institutes of Health, and the International Initiative for Environment and Public Health Cyprus.

J Allergy Clin Immunol. Published online July 14, 2015.

    
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