The amyotrophic lateral sclerosis assessment questionnaire (ALSAQ-40): tests of data quality, score reliability and response rate in a survey of patients

Abstract

Objectives: To evaluate response rate, data quality, and score reliability of the 40 item Amyotrophic Lateral Sclerosis Assessment Questionnaire in a survey of MND patients.

Design: A survey of members of the MND Association of the UK, of which half were randomly allocated to receive a survey instrument from the MND Association and the other half allocated to receive the MND Association survey instrument and also the ALSAQ-40 questionnaire.

Sample: Five hundred patients were randomly selected from the membership lists of the MND Association, of whom 250 received the MND Association Survey and the ALSAQ-40.

Results: Response rate to the survey was 59.2%. Over half of the respondents received the ALSAQ-40. Data for individual items were analysed and found to be distributed across all response categories. All items were found to be highly associated with the scales to which they contribute. Internal consistency reliability of all the five scales of the ALSAQ-40 was also found to be high.

Conclusion: Inclusion of the ALSAQ-40 into the survey did not have an adverse effect upon response rates. Furthermore, the ALSAQ-40 was shown to have highly desirable psychometric properties. This paper provides further evidence of the reliability and validity of the measure.