Development of the Norfolk quality of life tool for assessing patients with neuroendocrine tumors

To develop a disease-specific questionnaire for identifying domains having the greatest impact on the quality of life (QOL) of patients with neuroendocrine tumors (NETS). Patient responses to clinical interviews provided an 80-item initial pool for the development of the QOL-NET. The Delphi panel reviewed the items for content validity; the patient focus group reviewed the items for content/readability. Domains were derived from analysis of224 questionnaire responses. After principal components analysis, a scree plot suggested 7 domains. Exploratory factor analysis with forced 7-factor varimax rotation determined an ideal structure. Reliability/reproducibility was determined by test/retest 4 to 6 weeks apart. Logistic regression determined each domain score. All 7 domains exhibited strong internal consistency (Cronbach alpha = 0.86-0.97). Physical functioning contributed 40% of the total QOL score, followed by flushing, gastrointestinal symptoms, respiratory, cardiovascular, depression, and attitude domains. Most items loaded 0.40 or higher. No significant differences in test and retest scores. The mean values for the total QOL and 4 of 7 factor scores were significantly higher (P < 0.05) for NETS than controls: sensitivity was 71.4% and specificity was 69.6% to discriminate the NETS from the controls. We developed a 7-domain tool to determine QOL in NETS. Strong internal consistency exists within each domain of the QOL-NET. The QOL-NET is reliable and reproducible but weakly identifies NETS. Physical functioning is a greatest contributor to QOL impairment in NETS.