A Double-Blind Multicenter Group Comparative Study of the Efficacy and Safety of Nedocromil Sodium in the Management of Asthma: Methods (3)
The SRTs were withheld for 24 hours and other bronchodilators for six hours prior to these tests, and visits were scheduled, where possible, for the same time of day. Patients were questioned about any adverse treatment experiences. At the final visit, blood and urine samples were taken, and clinicians and patients assessed the effectiveness of the trial treatments (1 = very effective to 5=made condition worse), relephone contact was made during treatment weeks 4, 8 and 12 to remind the patients to continue with the treatments, complete the diary card, and record any unusual symptoms. The patients gave their written informed consent to participate in the study, and the protocol and informed consent form were approved by the Institutional Review Board of each center.
The two treatment groups were assessed for prestudy comparability using Fishers Exact Test and two-sample f-tests within centers, and the Mantel Haenszel Test and two-way (center by treatment) analyses of variance across centers for dichotomous and quantitative variables, respectively. Baseline assessment of asthma severity was analyzed using the Wilcoxon rank-sum test, within, and an Extended Mantel-Haenszel analysis, across, centers. buy flovent inhaler
The comparison of treatment effects within and across centers was based on the nonparametric methods of Koch and Amara for stratified (center) randomization covariance analysis of ranks. Separate analyses of variance were performed to summarize results from individual centers and two-way (center by treatment) analyses of covariance, with the baseline score as the covariate, to evaluate treatment group differences. Similarly, a Wilcoxon rank-sum test and an Extended Mantel-Haenszel test were used for clinician and patient opinions of treatment. A two-way (patient by center) analysis of covariance (baseline score as covariate) was performed on the cumulative daily means of the sum of the day and night-time asthma scores (the latter normalized to the daytime score prior to summing) of weeks 1 to 2 to assess the speed of onset of effect of the treatments. Analysis of covariance techniques was used to take account of the between subject variability as assessed during the baseline period. Unadjusted treatment group mean scores, however, are given throughout the results.