key: cord-0957709-7zhqtt2r
authors: Masoli, Matthew; Lanario, Joseph W.; Hyland, Michael E.; Menzies-Gow, Andrew; Mansur, Adel H.; Allen, David; Dodd, James W.; Hayes, Gemma; Valderas, Jose M.; Lamb, Sarah E.; Jones, Rupert C.
title: The Severe Asthma Questionnaire: sensitivity to change and minimal clinically important difference
date: 2021-06-17
journal: Eur Respir J
DOI: 10.1183/13993003.00300-2021
sha: 1421f530e2a22248006cee78351af2245b3acab5
doc_id: 957709
cord_uid: 7zhqtt2r

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

110 patients were recruited from six UK specialist asthma centres who were initiating a National Institute of Health and Care Excellence approved biologic treatment as part of usual care (62% female, mean age 49 years, mean forced expiratory volume in 1 s 67% of predicted). Participants completed the SAQ at baseline and completed the SAQ and a Global Rating of Change (GRoC) questionnaire [3] at 4, 8, 12 and 16 weeks after starting treatment. Patients responded to the 16 items of the SAQ using a 7-point scale, and responses were scored to produce an overall SAQ score from the mean of 16 items, and three subscale scores (My Life, My Mind, My Body) from the means of subsets of those 16 items [4] . In addition, patients provided a single response to a 100-point Borg-type rating of global quality of life, the SAQ-global. Questionnaires with >10% missing items were deemed invalid. Baseline mean±SD scores demonstrated significant health-related quality of life impairment across all aspects of the SAQ: 3.65±1.49 for the SAQ, 3.74±1.62 for My Life subscale, 3.78±1.78 for My Mind subscale, 3.34±1.51 for My Body subscale and 45.50±23.67 for the SAQ-global. Questionnaire change scores were calculated by subtracting the baseline score from the follow-up score, so that positive change scores indicated improvement in quality of life. There was a significant ( p<0.01) improvement between baseline and 4 weeks for the SAQ, the subscales of the SAQ and the SAQ-global, and improvement was maintained for subsequent weeks.

Patients were asked to rate the GRoC in terms of improvement by circling a statement "which best describes how you feel since starting your new treatment for your asthma". We analysed GRoC responses into any one of six categories: 1) "any degree of deterioration", 2) "no change", 3) "a little better", 4) "somewhat better" or 'moderately better", 5) "a good deal better" and 6) "a great deal better". Perceived change of "a little better" was defined as the point of the MCID following normal practice. In order to take full advantage of the repeated measures design, we used all available data where a GRoC rating was accompanied by a valid questionnaire change score over the 16-week study but excluded scores where the GRoC category was the repeat or deterioration of the previous week, as such scores could be less reliable due to increased recall bias caused by the intervening experiences. The study received ethical approvals @ERSpublications 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 These data show that the MCID for the SAQ is 0.5 and for the SAQ-global is 11. The MCID for the subscales of the SAQ are similar to that of the SAQ. Based on data reported elsewhere [1] , the standard error of measurement [5] gives an MCID of 0.5 for the SAQ and 6.0 for the SAQ-global. The standard error of measurement method provides an estimate of statistical discrimination and should not normally be greater than that provided by the anchor method. An MCID of 0.5 is reported by the authors of another asthma questionnaire, the Asthma Quality of Life Questionnaire (AQLQ) [6] that, like the SAQ, asks patients to rate on a 7-point scale. However, the similarity in results should be interpreted cautiously as there are some differences in the anchor methodology, and the assessment of the MCID of the AQLQ was based on the mean of only 10 judgements. Other asthma questionnaires, such as the St George's Respiratory Questionnaire [7] have other forms of response format and are therefore not comparable.

In addition to providing the MCID for the SAQ, our data provide information about the multiples of the MCID that are equivalent to larger degrees of perceived change. A "great deal better" is approximately four times the MCID for the SAQ and three times the MCID for the SAQ-global. A "good deal better" is approximately twice the MCID for the SAQ and twice the MCID for the SAQ-global. These additional values can be used to assess the clinical significance of changes that are much greater than the MCID, such as in super-responders.

The SAQ was developed with patients who contributed as partners to the content, wording and format of the questionnaire [8, 9] . The 16 items are validated to be used as a single scale (SAQ) [1] or as three subscales (My Life, My Mind, My Body) [4] , and the questionnaire also provides a global estimate of quality of life (SAQ-global). In this paper we have presented the MCID for all scoring methods. 

The construction and validation of the Severe Asthma Questionnaire

Recommended methods for determining responsiveness and minimally important differences for patient-reported outcomes

Global rating of change scales: a review of strengths and weaknesses and considerations for design

Validation of subscales of the Severe Asthma Questionnaire (SAQ) using exploratory factor analysis (EFA)

Identifying meaningful intra-individual change standards for health-related quality of life measures

Determining a minimal important change in a disease-specific quality of life questionnaire

The St George's respiratory questionnaire

How patient participation was used to develop a questionnaire that is fit for purpose for assessing quality of life in severe asthma

A qualitative study of the impact of severe asthma and its treatment showing that treatment burden is neglected in existing asthma assessment scales

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AstraZeneca, personal fees and non-financial support from Teva, and personal fees from Novartis, GlaxoSmithKline, Sanofi, Roche and Vectura, outside the submitted work. 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. 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. J.W. Dodd has nothing to disclose. G. Hayes has nothing to disclose. J.M. Valderas has nothing to disclose. 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. 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. Support statement: This work was supported by GlaxoSmithKline Investigator sponsored studies (ISS) grant: ISS Number 8994. Funding information for this article has been deposited with the Crossref Funder Registry.