Copyright ©ERS Journals Ltd 2003 Distribution of therapeutic response in asthma control between oral montelukast and inhaled beclomethasone1 Merck Research Laboratories, Merck & Co., Inc., Rahway, NJ, USA. 2 Clinicas Medicas, Guatemala City, Guatemala. 3 United States Human Health, Merck & Co., Inc., Horsham, PA, USA. 4 Hospital Mexico, Instituto Costarricense de Investigaciones Clinicas, San Jose, Costa Rica. 5 Hospital de Clinical Caracas, Caracas, Venezeula CORRESPONDENCE: T.F. Reiss, Merck Research Laboratories, RY 34B-328, Rahway, NJ , 070651900, USA. Fax: 1 7325947830. E-mail: theodore_reiss@merck.com Keywords: asthma, asthma control days, beclomethasone, forced expiratory volume in one second, leukotriene receptor antagonist, montelukast
Received: April 8, 2002
The distribution of responses in study populations provides a novel method of comparing the benefit of two treatments. This 6-week, randomised, placebo-controlled, double-blind study compared the effectiveness of oral montelukast with inhaled beclomethasone in chronic asthma by assessing the distribution and overlap of patient responses to therapy, as measured by a clinical outcome (asthma control days).
A total of 730 adult patients with asthma, age 1565 yrs, with a forced expiratory volume in one second (FEV1) at baseline of 5085% of predicted and The overlap of the distribution of responses between the montelukast and beclomethasone groups was 89% for per cent asthma control days and 96% for change from baseline in FEV1. The mean (±sd) per cent asthma control days in the montelukast and beclomethasone groups was significantly higher than that in the placebo group (placebo 40.0±35.8, montelukast 50.7±37.1, beclomethasone 57.9±36.1). The mean differences between montelukast and placebo, beclomethasone and placebo, and montelukast and beclomethasone were significant. The mean per cent change (±sd) from baseline in FEV1 was 12.1±18.7 and 13.9±20.8 in the montelukast and beclomethasone groups, respectively, and significantly greater than that in the placebo group (6.4±20.1); there was no significant difference between the montelukast and beclomethasone groups in mean values or response distribution. There was also no difference among treatment groups in the frequency of adverse experiences. A comparison of the response distribution is an important approach to comparing therapies; montelukast and beclomethasone provided similar response distributions for the end-point of per cent asthma control days over a 6-week treatment period. Although the incidence of asthma has increased substantially over the last two decades in children and adults 1, major advances have also been made in understanding the pathophysiology of this chronic inflammatory disease. Cysteinyl leukotrienes, the products of inflammatory cells such as eosinophils and mast cells, are inflammatory mediators that play an important role in the pathophysiology of asthma 25. Antileukotriene agents, including montelukast, zafirlukast, pranlukast and the 5-lipoxygenase inhibitor zileuton, act by blocking the effects of the cysteinyl leukotrienes. Montelukast is an orally active, potent and specific cysteinyl leukotriene receptor antagonist that has been shown to improve the signs and symptoms of asthma in several placebo-controlled trials of patients with chronic asthma 2 yrs of age 69. National and international consensus guidelines for treating asthma recommend daily controller therapy for patients with persistent asthma 10, 11. Inhaled corticosteroids are widely used as an initial controller therapy and antileukotriene agents are currently recommended as an alternative controller therapy. However, there are limited data directly comparing inhaled corticosteroids with antileukotrienes 8. According to treatment guidelines, the aim of long-term therapy for asthma is to minimise symptoms, avoid asthma exacerbations and maintain normal physical activity 10, 11. However, therapeutic efficacy in most clinical trials is assessed by changes in surrogate end-points, such as spirometry and home peak flow monitoring. Instead, measures of more clinically relevant, patient-oriented outcomes, such as symptoms, need for rescue medication, and incidence of asthma exacerbations, may better reflect asthma control as defined by treatment guidelines 10, 11. Additionally, most analysis of clinical trials rely on comparisons of mean values. Such data, however, frequently fail to reflect important clinical information present in the variability around the mean response, otherwise known as the distribution of response in the population. The overlap in response distributions can frequently provide a more complete determination of clinical comparability because the range of response to therapy of individuals in the study population is taken into account 12.
The purpose of this study was to compare the effectiveness of montelukast and inhaled beclomethasone in the treatment of adult patients with asthma by evaluating the response distributions for both conventional measurements such as airway function, as well as an outcome measure (the asthma control day) that incorporates symptoms, rescue medication use, and incidence of asthma attacks. The primary hypothesis of the study was that the overlap of patient response in the percentage of asthma control days between montelukast and beclomethasone would be
Patients Male and female patients aged 15 yrs with 1-yr history of asthma symptoms were enrolled in the study. Patients were eligible for enrollment if they had a forced expiratory volume in one second (FEV1) at baseline of 5085% of the predicted value, with 15% improvement in FEV1 after inhaled ß-agonist and average daily use of more than two puffs of ß-agonist during the run-in period. Eligible patients had a smoking history of 7 pack-yrs and were nonsmokers for 1 yr. A total of 730 patients were randomised into the study. During the study, patients continued to take a short-acting inhaled ß-agonist as necessary to control asthma symptoms. Use of oral, intravenous and intramuscular corticosteroids was not permitted within 1 month of the start of the placebo run-in period. In addition, patients were excluded from the study if they had received inhaled corticosteroids within 2 weeks, astemizole within 3 months or xanthine derivatives, oral or long-acting inhaled ß-agonists, cromolyn sodium or nedocromil, inhaled anticholinergic agents, oral leukotriene receptor antagonists or leukotriene synthesis inhibitors within 1 week before the start of the placebo run-in period. Patients could receive immunotherapy if it had started >6 months before the start of the placebo run-in period and if the dosage was expected to remain the same during the study. Females of childbearing potential were required to have a negative pregnancy test (serum ß-human chorionic gonadotropin) prior to the start of the placebo run-in period. The study protocol was approved by local ethics review committees and all enrolled patients gave written informed consent to participate in the study.
Study design Spirometry was conducted between 06:00 and 10:00 h at each clinic visit using a standard spirometer (Model PB 100; Puritan-Bennett, Lenexa, KS, USA) in accordance with the reproducibility and acceptability criteria of the American Thoracic Society 14 and a standard quality control system 15. The largest FEV1 and forced vital capacity from the three best acceptable manoeuvres were recorded. A daily asthma diary card was completed by each patient. This diary card contained a daytime section that captured the total puffs of salbutamol taken since arising and a night-time section that captured nocturnal awakenings because of asthma and total puffs of salbutamol taken since bedtime. Daytime asthma symptoms were not recorded. The nocturnal awakening question has been shown to have acceptable measurement 16. At the final study visit or at discontinuation, patients and physicians independently evaluated the change in the patients' asthma condition by selecting the most appropriate response from a seven-point global evaluation scale, ranging from very much better (score 0) to unchanged (score 3) to very much worse (score 6). When completing the physician global evaluation, the investigator was blinded to all study data except for the following items from the final visit: patients' oral history, vital signs, physical examination and spirometry results.
Statistical analysis An intention-to-treat approach was followed in the analysis of efficacy data. All patients with a baseline and at least one postrandomisation measurement were included in the analysis according to the group to which they were randomised. All randomised patients were included in the analysis of safety. The analysis of per cent overlap for the end-points of asthma control days and FEV1 was based on a standard nonparametric statistical method (Mann-Whitney U statistical version of the Wilcoxon rank test) that permits comparison of each individual in the beclomethasone group to each individual in the montelukast group; it was thus a patient-based rather than a population-based measure 1821. The standardised Mann-Whitney U statistic and its corresponding variance were used to calculate a 95% confidence interval (CI) for the true probability that a randomly chosen patient in the beclomethasone group experienced a greater percentage of asthma control days than a randomly chosen patient in the montelukast group. Equivalence between the treatment groups would result in a value of 0.5 (i.e. a 50% probability). To facilitate the interpretation of results in terms of overlap in the distribution of percentage of asthma control days and thus the treatment difference, estimates and 95% CI limits were transformed to a percentage overlap scale (ranging from 0100%), with 100% corresponding to a U statistic of 0.5). In addition, analysis of variance (ANOVA) was performed to corroborate the results. For the end-points of FEV1 and average daily ß-agonist use, change (or per cent change) from prerandomisation baseline was analysed. An ANOVA was used to compare the treatment means for all end-points except the percentage of patients with asthma attacks, which was compared by logistical regression. Compliance to study medication was assessed from patient-reported daily diary cards and represents the average of tablet (montelukast or placebo) and inhaler (beclomethasone or placebo) compliance.
Power
Patients A total of 730 randomly allocated patients (479 females and 251 males) were randomised into the study (table 1
Of these patients, 679 (93%) completed the study. Altogether, 51 patients discontinued the study prematurely (9.7, 7.0 and 6.1% in the placebo, montelukast and beclomethasone groups, respectively), six because of a clinical adverse experience (three each in the placebo and beclomethasone groups), three because of a laboratory adverse experience (one in the montelukast and two in the beclomethasone groups) and 42 because of other reasons, such as protocol deviation, lost to follow-up, or withdrawal of consent (7, 21 and 14 patients in the placebo, montelukast and beclomethasone groups, respectively). The per cent patient compliance (mean±sd) for placebo, montelukast and beclomethasone was 98.0±3.4, 98.4±3.8 and 98.1±3.5, respectively.
Efficacy results
Mean per cent of asthma control days are shown in table 2
Mean baseline values of FEV1 were comparable among the three treatment groups (table 1
There was no significant difference between the active treatment groups in per cent change from baseline in FEV1 (table 2
The per cent asthma control days (mean±sd) for patients with a baseline % pred FEV1 of
Mean daily ß-agonist use was comparable at baseline among the three treatment groups (table 1
Improvements in both the montelukast and beclomethasone groups were significantly greater (p<0.05) than in the placebo group in patient and physician global assessments (table 2
There were 15 out of 101 (15%), 17 out of 308 (6%) and 12 out of 308 (4%) patients in the placebo, montelukast and beclomethasone groups, respectively, who experienced at least one asthma attack (table 2
Safety results
The intent of this study was to investigate asthma control achieved by two different therapies on a clinically relevant end-point, the asthma control day, and to compare the response distribution between groups. The definition of an asthma control day in this study combined four parameters that are commonly measured in studies of asthma therapy, namely, daily use of ß-agonist, night-time awakenings, use of oral corticosteroid rescue and need for unscheduled asthma-related medical care. This definition is similar to that of the episode-free day proposed by Sculpher and Buxton 17 as a composite effectiveness measure for use in a cost-effectiveness analysis. An episode-free day was defined as one during which there is an absence of asthma attack, need for rescue medication, sleep disturbance caused by asthma or adverse event. This end-point represents the desired goal of consensus guidelines for treating asthma 10, 11: a day when asthma symptoms are minimal and there is limited or no need for the use of rescue medication. For the asthma control day end-point, the prespecified primary analysis in this study was the per cent overlap in the distribution of patient responses between the montelukast and beclomethasone treatment groups. This approach was specifically chosen to obtain new and relevant clinical information not available from comparisons of mean or median responses. The overlap analysis allows for a more complete determination of clinical comparability because the response range to therapy of the entire population is taken into account. Thus, a comparison of the relative effects requires the entire range of patient response, and therefore the use of individual patient responses, to be included in the analysis 12. It was found that treatment for 6 weeks with either oral montelukast or inhaled beclomethasone produced a distribution of patient response to treatment that was similar in the montelukast and beclomethasone groups for both the percentage of asthma control days and FEV1. The mean per cent of asthma control days was significantly higher among patients treated with beclomethasone (57.9%) than with those treated with montelukast (50.7%); however, values for FEV1 (mean per cent change from baseline) were similar between the montelukast and beclomethasone groups (12.1 and 13.9%, respectively). Both therapies showed significantly greater improvement than placebo in multiple parameters of asthma control. Comparisons of the response distribution have been previously applied in other areas of clinical research, such as pharmacokinetics and vaccine efficacy, as well as in other areas of investigation. Gastwirth 20 noted that examination of distribution data leads to conclusions different from those derived from median values; for example, in evaluating the earnings differential between males and females, an improvement (decrease) in sex-based income discrepancy was identified when evaluating median data but showed that the discrepancy was in fact increasing on the basis of the overlap of distribution. It was concluded that the median data tended to overestimate the effect. Similarly, in the present study, there was a clinically important degree of overlap (>85%) in the response of patients treated with either active therapy despite a difference in mean percentage of asthma control days that favoured inhaled beclomethasone. The distribution plot also provides valuable information about the variability and the range of individual patient responses. In this study, both active therapies produced a similar range of responses for FEV1 as well as for percentage of asthma control days, a finding that suggests these drugs are similar in effect in this regard. Both montelukast and beclomethasone were generally well tolerated and the incidence and types of adverse experiences were similar in the two groups. The overall incidence of clinical and laboratory adverse events in these two groups was lower than that in the placebo group. Asthma exacerbations occurred more frequently in the placebo group (18, 7 and 4% of patients affected in the placebo, montelukast and beclomethasone groups, respectively). Study medications were administered at a constant dosage throughout the treatment period and were allowed to be administered either with or without a spacer device according to the wishes of the patient and physician. This was done to simulate real world conditions and to provide a comparison of treatments as they are used in practice 22. A dose of beclomethasone (200 µg twice daily) that is within the recommended starting-dose range (200500 µg) of the Global Initiative for Asthma guidelines was chosen 11. In addition, Chanez et al. 23 showed that both high (800 µg) and standard (200 µg) initial doses of budesonide were equally effective in controlling symptoms and improving lung function in mild-to-moderate asthma. The dose of montelukast is the labelled dose for adults (10 mg once daily), as established in dose-ranging studies 24, 25, 26. In patients approximating GINA guidelines for mild patients, montelukast has demonstrated treatment benefit 27. In conclusion, the distribution and overlap of patient responses (as assessed by asthma control days and change from baseline in forced expiratory volume in one second) indicate that during 6 weeks of therapy there is a generally similar distribution of response seen with montelukast and inhaled beclomethasone as administered in the trial and that the approach utilising overlap distributions to compare treatments is clinically useful and deserves wider application in the context of clinical trials.
The authors would like to thank L.O. Eriksson and A. Esposito for support with study logistics. The Montelukast Study Group for this protocol consisted of the following investigators: M. Bernstein, F. Caballero, M. Fitzgerald, F. Galleguillos, J. Hébert, J. Hetzel, J.R. Jardim, M. Laviolette, G. Martinez, P. Patel, J.R. Perez-Padilla, A.P. Garcia-Calderon, F. Prieto, P. Renzi, G.G. Rodriguez Gomez and C.V. Ferreyros.
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||