Validation of a disease-specific quality-of-life questionnaire in a large sample of Dutch achalasia patients.

The aim of this study was to validate a translated version of an achalasia-specific quality-of-life questionnaire (achalasia-DSQoL) by examining its psychometric properties in a Dutch cohort of achalasia patients. The achalasia-DSQoL was administered to 171 treated achalasia patients together with a clinical symptom score and the RAND-36. Validation methods included factor analysis, known-group techniques, Cronbach's alpha and Spearman rank correlation with other questionnaires and feasibility. About 72.5% of the achalasia patients completed the questionnaires. The achalasia-DSQoL showed evidence of an underlying construct and seems reliable with a Cronbach's alpha of 0.77. The question concerning heartburn did not correlate with the other items on the questionnaire. Known-group techniques demonstrated that the achalasia-DSQoL discriminates between achalasia patients in clinical remission and patients who are not. There was a moderate correlation between the achalasia-DSQoL and the RAND-36 subscales. The questionnaire was easy in use. The translated version of the achalasia-DSQoL is a valid and reliable instrument to compare groups of achalasia patients although the question concerning heartburn should be excluded.