Short-acting beta 2 agonists for stable chronic obstructive pulmonary disease.
BACKGROUND
Chronic Obstructive Pulmonary Disease (COPD) is a chronic condition characterised by progressive airflow limitation that is at most partially reversible. Despite the lack of reversibility patients often report symptomatic improvement with short-acting beta 2 bronchodilator medications. They are used on either an "as required" or a "regular plus as required basis" and they may be used in conjunction with other bronchodilator medicines such as ipratropium and methylxanthines. These medicines are used in the management of both stable and acute exacerbations of COPD. This review examined the effect of short-acting beta 2 bronchodilators given by inhalation in stable COPD.


OBJECTIVE
To determine the clinical effect and assess the adverse effects of inhaled short-acting beta 2 agonist bronchodilators compared with placebo in stable COPD.


METHODS
Only randomised controlled trials (RCTs) were considered. RCTs were identified using the Cochrane Airways Group database (CENTRAL). In addition, the reference lists of review articles and RCTs retrieved in full were searched for other potentially relevant citations.


METHODS
Only trials with adult patients with stable COPD, as defined by internationally accepted guidelines (ATS, ERS or BTS) were included in this review. All trials had a minimum duration of 7 days of regular treatment with short-acting beta 2 bronchodilators given by inhalation and compared with placebo. Data from trials where beta 2 agonists were used alone or in combination with other medicines (e.g. ipratropium bromide) were used only if there was a direct comparison between beta 2 bronchodilator alone and placebo.


METHODS
Outcomes were analysed as continuous or dichotomous outcomes, using standard statistical techniques. For continuous outcomes, the weighted mean difference (WMD) and 95% confidence intervals were calculated and for dichotomous outcomes, the odds ratio was calculated with 95% confidence intervals by Peto's methods. Funnel plots were used to test for publication bias.


RESULTS
Thirteen studies were included in this review. Most had small sample sizes and some of the sutides used very short-acting outdated compounds. All the studies used a cross-over design and were of high quality. Spirometry done at the end of study period was measured after administration of treatment (post-bronchodilator) which showed both FEV1 (0.150 L/min, 95%CI: 0. 02-0.28) and FVC (0.310 L, 95%CI: 0.00-0.62) to improve significanly but slightly when compared to placebo. A few studies measured FRC, airway resistance or conductance at the end of the study period. In all cases these measurements were done several hours after treatment, and no significant differences (p>0.05 in all cases) were found between the bronchodilator and placebo groups. Walking test Large increases in 6MW distance was observed in two studies, however one study did not show any positive improvements. There was a large increase in the 12MW distance as shown by one study. Due to the small number of studies reporting this outcome no significant differences were found in the walking distance between the bronchodilator and placebo groups. Peak Flow Rate Both morning (36. 04 L/min; 95%CI: 0.80-71.27) and evening (36.68 L/min; 95%CI: 2. 47-70.89) PEFR were significantly higher during active treatment than during placebo. Symptoms Breatlessness was measured on various scales therefore data that were presented in a suitable form were combined using standardized means for inclusion in the analysis. A significant improvement (-0.33; 95%CI: -0.58 to -0.07 with p=0.01) in the breathlessness score was observed during treatment with beta-2 agonist when compared to placebo. Cough was reported to improve significantly (data not usable) during treatment with beta2 agonist in one study but not in two others. A non-significant decrease in sputum production was reported by Wilson 1980, however four other studies reported no
Sestini
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Institute of Respiratory Diseases, University of Siena, Viale Bracci 3, 53100, Siena, Italy. sestini@unisi.it
Ram
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D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000328:Adult; D000420:Albuterol / Q000627:therapeutic use; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000188:drug therapy*; D013726:Terbutaline / Q000627:therapeutic use
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D013726:Terbutaline; D000420:Albuterol