Use of changes in symptoms to predict changes in lung function in assessing the response to asthma therapy

Background: The majority of adult patients with asthma are managed by prima ry care providers. Although there is no generally accepted gold standard fo r the assessment of asthma severity in general practice, treatment decision s and modifications to therapy are strongly influenced by patients' symptom s and history of asthma medication use. Objectives: The primary goal of this study was to determine whether there i s a correlation between changes in asthma symptoms during treatment and cha nges in lung function, as measured by peak expiratory flow (PEF). A, second ary goal was to compare the relative efficacy tin terms of improvement in a sthma symptoms and lung function) of 3 commonly used asthma treatments: inh aled fluticasone propionate, inhaled salmeterol xinafoate, and oral zafirlu kast. Methods: This was a retrospective comparison employing regression analyses of asthma symptom and lung function data from 2890 male and female adolesce nt and adult patients with persistent asthma who were enrolled in 8 randomi zed, double-blind, double-dummy, parallel-group studies. Data on patients' self-rated symptoms, PEF supplemental albuterol use, nighttime awakenings, and frequency of asthma exacerbations were used to ascertain whether there was a correlation between changes in asthma symptoms and changes in pulmona ry function, and to compare treatment effects. Results: Changes in patients' ratings of asthma symptoms after treatment wi th study medications showed a strong correlation with changes in lung funct ion. Similarly, changes in lung function were strongly correlated with chan ges in supplemental beta-agonist use and quality of life. In addition, flut icasone or salmeterol treatment resulted in significantly greater increases in mean morning PEF (P < 0.001), significantly greater decreases in sympto m scores (P less than or equal to 0.004), significantly fewer nights with a wakenings due to symptoms (P less than or equal to 0.017), and significantl y greater reductions in supplemental beta-agonist use (P < 0.001) compared with zafirlukast treatment or placebo. Patients treated with fluticasone or salmeterol also experienced significantly lower rates of asthma exacerbati on (3%) during treatment than did those receiving zafirlukast (7%) or place bo (12%) (P < 0.001 and P = 0.015, fluticasone and salmeterol, respectively ). Conclusion: These findings support the validity of primary care practitione rs' basing asthma-management decisions on patients' symptoms.