Escala Crq Epoc

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Thorax 1994;49:465-467

465

Reliability and validity of the chronic respiratory questionnaire (CRQ)
P J Wijkstra, E M TenVergert, R Van Altena, V Otten, D S Postma, J Kraan, G H Koeter

Asthma Centre, Beatrixoord Hospital, 9751 ND Haren, (Groningen), The Netherlands P J Wijkstra R Van Altena V OttenAbstract Background - The Chronic Respiratory Questionnaire (CRQ) is frequently applied to assess quality of life in patients with chronic obstructive pulmonary disease (COPD). However, the reliability and validity of this questionnaire have not yet been determined. This study investigates the reliability and validity of the four separate dimensions of the CRQ. Methods - The CRQ was administered ontwo consecutive days to 40 patients with COPD (mean FEV1 44% predicted, FEVj/ IVC 37% predicted). Internal consistency reliability of each dimension was investigated by Cronbach's a reliability coefficient, test retest reliability by the Spearman-Brown reliability coefficient (p), and content validity by Pearson's correlation coefficient between the CRQ and the symptom checklist (SCL-90). Results -Items of the fatigue, emotion, and mastery dimensions showed a high internal consistency reliability (a = 0-710 88) as well as a high test retest reliability (p above 0 90). These three dimensions correlated with comparable dimensions of the SCL-90. Items of the dyspnoea dimension showed a low internal consistency reliability (ox=0-53) and a test retest reliability of p = 0 73. Conclusions - Itemsof the dimensions fatigue, emotion, and mastery 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 dyspnoea dimension are less reliable and should not be included in the overall score of the CRQ in comparative research. However, by scoring the items of dyspnoea separately they may be useful for the evaluation ofthe effects of intervention in a specific patient.
(Thorax 1994;49:465-467)

these patients. Because these instruments are not sensitive enough to detect small changes7 after treatment, Guyatt and coworkers developed the Chronic Respiratory Questionnaire (CRQ).8 They showed that the CRQ was precise, valid, and responsive,89 but did not investigate the internal consistency reliability of theseparate dimensions. Furthermore, responsiveness to change is more an indication of the validity of a measuring instrument than a separate characteristic.'0 This means that reproducible and responsive measurement instruments may contain items which have nothing in common" - that is, the sets of items do not measure the dimensions they constitute. We have therefore investigated the internal consistencyand the test retest reliability of the separate dimensions of the CRQ. The content validity of the CRQ was assessed by correlating it with the symptom checklist (SCL-90). 12
Methods
PATIENTS

Forty patients with COPD (all smokers or exsmokers, table 1) with severe airways obstruction, participating in a rehabilitation programme were studied. All were admitted to hospital for two days and werestable (no recent exacerbations) with optimal drug management. Entry criteria were: (1) FEV, (forced expiratory volume in one second) < 60% predicted, and (2) FEVI/IVC (inspiratory vital capacity) < 50% both after two inhalations of 40 gg ipratropium bromide. Patients with evidence of ischaemic heart disease, intermittent claudication, musculoskeletal disorders, or other disabling diseases thatmight restrict a rehabilitation programme were excluded. The study was approved by the medical ethics committee of the University
Table 1 Mean (SD) characteristics of 40 patients with COPD
Sex (M:F) Age (years) FEV1b (1)
33:7 62-4 (5-0) 1-2 (0 3) 1-3 (0-4) 44.3 (10-6) 37-2 (7-9) 3-6 (0 9) 913 (17-2) 116-3 (14-1) 143-0 (25-1) 70-1 (27-4)

Department of Pulmonary Diseases, University Hospital,...