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

Lanario, Joseph W, Hyland, Michael E, Menzies-Gow, Andrew, Mansur, Adel H, Dodd, James W, Fowler, Stephen J, Jones, Rupert C and Masoli, Matthew (2020) Validation of subscales of the Severe Asthma Questionnaire (SAQ) using exploratory factor analysis (EFA). Health and quality of life outcomes, 18 (1). p. 336. ISSN 1477-7525. This article is available to all UHB staff and students via ASK Discovery tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs

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Abstract

BACKGROUND

The Severe Asthma Questionnaire (SAQ) is a health related quality of life (HRQoL) questionnaire validated for use in severe asthma. It is scored using the mean value of 16 items (SAQ score) in addition to a single item global rating of HRQoL (SAQ-global). The aim was to validate clinically relevant subscales using exploratory factor analysis (EFA).

METHODS

The SAQ was completed, along with measures of asthma control and EQ5D-5L by patients attending six UK severe asthma centres. Clinical data were included in the analysis. EFA using principal axis factoring and oblimin rotation was used to achieve simple structure of data.

RESULTS

460 patients with severe asthma participated, 65% women, mean age 51 (16-83) years. A three factor solution achieved best fit and showed that the SAQ items formed three distinct but inter-correlated groups of items where items were grouped in a way that was consistent with item content. The three subscales were differentially associated with clinically relevant variables (lung function and mood). Males and females interpreted the question of night disturbance in different ways.

CONCLUSIONS

This paper provides a template for best practice in the use of EFA when validating HRQoL subscales. The SAQ can be scored as three subscales with content reflecting three different constructs people with severe asthma use when making judgements about their lives. The subscale 'My Life' assesses the impact of severe asthma on different life activities, 'My Mind' assesses the perceived emotional impact and 'My Body' the impact of extra-pulmonary symptoms and side effects.

Item Type: Article
Additional Information: This article is available to all UHB staff and students via ASK Discovery tool http://tinyurl.com/z795c8c by using their UHB Athens login IDs
Subjects: W Public health. Health statistics. Occupational health. Health education
WF Respiratory system. Respiratory medicine
Divisions: Planned IP Care > Respiratory Medicine
Related URLs:
Depositing User: Jamie Edgar
Date Deposited: 19 Oct 2020 11:25
Last Modified: 19 Oct 2020 11:25
URI: http://www.repository.uhblibrary.co.uk/id/eprint/3556

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