Rate of Response of Individual Asthma Control Measures Varies and May Overestimate Asthma Control: An Analysis of the Goal Study

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Abstract
Background: Using a composite measure based on clinical outcomes, the GOAL study showed that achievement of Total Control of asthma was time dependent with the proportion of controlled patients continuing to rise through the year-long study. Taking data from this study, we compared time taken to achieve Total Control with time taken to achieve total control of each individual clinical criterion on treatment with salmeterol/fluticasone propionate (SFC) or fluticasone propionate (FP) alone. Methods: Time to achieving total control of individual outcomes (day-time symptoms, night-time awakenings, rescue medication use, PEF ≥80% predicted every day) were analyzed by Kaplan Meier plots and compared with achievement of composite Total Control. Results: Night-time awakenings responded most rapidly and daytime symptoms took longest to respond. After 12 weeks, the proportion of patients who achieved control of any individual clinical criterion was higher than the proportion who achieved control when using the composite outcome (no night-time awakenings achieved by 73% with SFC and 65% with FP; PEF ≥80% predicted every day, 55% and 45% respectively; no rescue usage 46% and 35% respectively; and no daytime symptoms, 35% and 24% respectively, compared with Total Control, 23% and 14% respectively). In every measure except night-time awakenings, more rapid responses were seen for SFC compared with FP alone. Conclusions: Speed of response of individual asthma measures varies and evaluation of control using any single measure overestimates total asthma control. Treatment should be continued until composite control is reached, rather than control of individual outcomes.