Development and testing of a cancer appetite and symptom questionnaire

BACKGROUND: Poor appetite and weight loss are common in patients with cancer, contributing to an increase in morbidity and mortality. Early identification of those at greatest risk is problematic. The Council on Nutrition Appetite Questionnaire (CNAQ) is short and easy to use, although it is not specific to cancer populations. The present study aimed to build on the CNAQ to develop a cancer appetite and symptom questionnaire (CASQ) for predicting weight loss in patients with cancer. METHODS: The content validity of the CNAQ was assessed by an expert panel (n = 41) using the content validity index (CVI). The resulting CASQ was tested for reliability among patients receiving radiotherapy (n = 34). Predictive validity of the CASQ was determined in patients with lung or upper gastrointestinal cancer (n = 185), comparing CASQ scores (possible range 0-48) recorded at baseline with percentage weight change after 12 weeks. RESULTS:  In all but one CNAQ item, the CVI was above the minimum level of agreement (>0.70). Comments from expert panel members led to minor modifications and the introduction of new items resulting in the 12-item CASQ. The intraclass correlation coefficient of the CASQ was 0.80 [95% confidence interval (CI) = 0.68-0.92] and the difference between total scores at two time points was -0.20 (95% CI = -1.21 to 0.80). The optimum cut-off point of the instrument to predict >10% weight loss was 29/30 (area under curve = 0.75; sensitivity 71%, specificity 66%, positive predictive value 19%, negative predictive value 95%) [Correction added on 30 April 2012, after first online publication: in the preceding sentence, <10% was corrected to >10%]. CONCLUSIONS: The CASQ can predict weight loss among patients with lung and upper gastrointestinal cancer. Acknowledgment of the low positive predictive value is needed if the instrument is to be used within clinical practice.