Study of Magnitude and Prediction of Response to Omalizumab and Mepolizumab in Adult Severe Asthma.

The only intervention will be that allocation of patients to omalizumab or mepolizumab (to both of which patients will be eligible) will be randomized, to avoid that the initial decision is biased by confounding factors that are likely, but unproven, to affect the treatment response. Then, in case of non-response, patients will be switched to the other drug, as routine clinical practice would indicate.

The only intervention will be that allocation of patients to omalizumab or mepolizumab (to both of which patients will be eligible) will be randomized, to avoid that the initial decision is biased by confounding factors that are likely, but unproven, to affect the treatment response. Then, in case of non-response, patients will be switched to the other drug, as routine clinical practice would indicate.