The Severe Asthma Questionnaire: sensitivity to change and minimal clinically important difference

The Severe Asthma Questionnaire (SAQ) is sensitive to change and clinically significant improvement was detected within 4 weeks of starting biologic therapy. The MCID of the SAQ is 0.5 and of the SAQ-global is 11. https://bit.ly/3poJqcG The Severe Asthma Questionnaire (SAQ) is a validated measure of the health-related quality of life of people living with severe asthma [1]. The minimal clinically important difference (MCID) of the SAQ has not been calculated. The MCID is useful for representing clinical as opposed to statistical significance. There are two main ways of calculating the MCID. Distribution methods define the MCID in terms of the relationship between the distribution of scores and mean change score. These methods are purely statistical and the relationship and formulae that constitute the MCID is determined by convention. By contrast, the anchor method [2] defines the MCID in terms of an independent anchor or criterion. When the anchor is the patient's perception of a just noticeable difference in their condition, then the anchor method has two advantages over the distribution method. First, the MCID is defined by a criterion and, therefore, has criterion validity rather than being only a convention. Second, the MCID is defined in terms of the patient's perception of treatment, and the patient's perception of their treatment is recognised as being an important outcome for clinical decision-making [2]. In this letter we present the MCID of the SAQ using the anchor method. eng this study with an investigator led non-promotional grant, they had no involvement in the study, analysis or write up), personal fees from AstraZeneca (independent data monitoring committee member), personal fees from Novartis (participation in advisory board), during the conduct of the study. Conflict of interest: J.W. Lanario reports grants from GSK, during the conduct of the study; personal fees from Novartis, outside the submitted work. Conflict of interest: M.E. Hyland reports grants from GSK, during the conduct of the study; personal fees from GSK, outside the submitted work. Conflict of interest: A. Menzies-Gow reports grants and personal fees from AstraZeneca, personal fees and non-financial support from Teva, and personal fees from Novartis, GlaxoSmithKline, Sanofi, Roche and Vectura, outside the submitted work. Conflict of interest: A.H. Mansur reports grants, personal fees, non-financial support and other (for various activities that include talks, advisory board meeting, sponsorship for conferences) from NAPP, Cheisi, AstraZeneca, GSK, Sanofi, Teva, outside the submitted work. Conflict of interest: D. Allen reports personal fees (advisory boards) from AstraZeneca and GSK, personal fees and non-financial support from Teva (speaker fees, and sponsorship support to attend conferences), outside the submitted work. Conflict of interest: J.W. Dodd has nothing to disclose. Conflict of interest: G. Hayes has nothing to disclose. Conflict of interest: J.M. Valderas has nothing to disclose. Conflict of interest: S.E Lamb was on the Health Technology Assessment (HTA) Additional Capacity Funding Board, HTA End of Life Care and Add-on Studies Board, HTA Prioritisation Group Board and the HTA Trauma Board. Conflict of interest: R.C. Jones reports grants from GlaxoSmithKline, during the conduct of the study; grants, personal fees and non-financial support from AstraZeneca and GlaxoSmithKline, personal fees and non-financial support from Boehringer Ingelheim, Novartis, Nutricia and OPRI, outside the submitted work.This article is freely available online. Click on the 'Additional Link' above to access the full-text via the publisher's site.Published version, accepted version (12 month embargo