Is overall asthma control being achieved? A hypothesis-generating study

The efficacy of asthma therapy is traditionally measured using single end-points. In contrast, the aim of therapy is to achieve overall control, defined by management guidelines as achieving a number of treatment goals. These goals reflect expert opinion, rather than being evidence based. The objective of this study was to determine whether guideline-defined asthma control is achievable. Eight studies of salmeterol/fluticasone propionate combination therapy were analysed using three asthma control measures of varying stringency, derived from the guideline goals. For each measure, only patients meeting all goals were classified as controlled. The analysis demonstrated that asthma control, as defined by management guidelines, can be achieved. For a given therapy, similar proportions of patients achieved control irrespective of disease severity, suggesting that outcome expectations should not be reduced for patients with more severe disease. Substantially more patients achieved the target values for individual goals than achieved overall control, indicating that reliance on individual end-points is likely to result in significant overestimation of true control. The findings of this hypothesis-generating study should be prospectively tested. Future research will include a randomized controlled study designed to assess the proportion of patients able to achieve overall control of asthma when treatment is titrated appropriately.