Short Form Chronic Respiratory Questionnaire Validation in a Lung Cancer Population

Abstract

Background: The Chronic Respiratory Questionnaire short form (SF-CRQ) is frequently used in patients with obstructive pulmonary disease and it has demonstrated excellent psychometric properties. The CRQ (both in its original or short form) has not been previously used in the assessment of lung cancer patients’ HRQL. Therefore this study, being part of a larger therapeutic trial, aims to evaluate the psychometric properties of the SF-CRQ in patients diagnosed with thoracic malignancies. Methods: Forty-six patients were assessed at two time points (with a four-week interval) using the SF-CRQ, the modified Borg Scale, five numerical rating scales related to perceived severity of breathlessness, and the Hospital Anxiety & Depression Scale. Internal consistency reliability was investigated by Cronbach’s α reliability coefficient, test-retest reliability by Spearman-Brown reliability coefficient (p) and convergent validity by Pearson’s correlation coefficient between the SF-CRQ, and the conceptual similar scales mentioned above and content validity was also explored. A principal component factor analysis was performed.Results: The internal consistency was high, indicated by an α=0.88 (baseline) and 0.91 (after one month). The SF-CRQ had good stability with test-retest reliability ranging from r=0.64 to r=0.78, p<0.001. Factor analysis suggests a single construct in this population showing that the items of the SF-CRQ scale are strongly correlated and represent the conceptual meaning of the underlying construct, which is the quality of life of lung cancer patients as related to breathlessness. Conclusion: The data analyses supported the convergent, content, and construct validity of the SF-CRQ indicating this is a valid and reliable instrument for the assessment of quality of life related to breathlessness in lung cancer patients. This study is the first study that provides initial data of the psychometric properties of the SF-CRQ in lung cancer patients, and further validation with larger sample sizes and across different settings and dyspnea severity is needed. Keywords: breathlessness, quality of life, lung cancer patients, Chronic Respiratory Questionnaire.