RELIABILITY AND VALIDITY OF THE CHRONIC RESPIRATORY QUESTIONNAIRE (CRQ)

Background - The Chronic Respiratory Questionnaire (CRQ) is frequently applied to assess quality of life in patients with chronic obstructiv e pulmonary disease (COPD). However, the reliability and validity of t his questionnaire have not yet been determined. This study investigate s the reliability and validity of the four separate dimensions of the CRQ. Methods - The CRQ was administered on two consecutive days to 40 patients with COPD (mean FEV(1) 44% predicted, FEV(1)/ IVC 37% predict ed). Internal consistency reliability of each dimension was investigat ed by Cronbach's alpha reliability coefficient, test retest reliabilit y by the Spearman-Brown reliability coefficient (p), and content valid ity by Pearson's correlation coefficient between the CRQ and the sympt om checklist (SCL-90). Results - Items of the fatigue, emotion, and ma stery dimensions showed a high internal consistency reliability (alpha = 0.710-0.88) as well as a high test retest reliability (p above 0.90 ). These three dimensions correlated with comparable dimensions of the SCL-80. Items of the dyspnoea dimension showed a low internal consist ency reliability (alpha = 0.53) and a test retest reliability of p = 0 .73. Conclusions - Items of the dimensions fatigue, emotion, and maste ry of the CRQ are reliable and valid and can be used to assess quality of life in patients with severe airways obstruction. Items of the dys pnoea dimension are less reliable and should not be included in the ov erall score of the CRQ in comparative research. However, by scoring th e items of dyspnoea separately they may be useful for the evaluation o f the effects of intervention in a specific patient.