OBJECTIVES: To assess and provide an initial psychometric evaluation of the Nausea and Vomiting Questionnaire (NVQ) in patients with type 2 diabetes mellitus (T2DM) receiving a glucagon-like peptide-1 agonist (GLP-1) therapy.
METHODS: Data were collected from a non-interventional, cross-sectional study via a web-based survey administered to patients self-reporting a diagnosis of T2DM, who experienced nausea and/or vomiting after initiating treatment with a GLP-1 (within prior 6 months). In addition to the NVQ, subjects also completed the Functional Living Index-Emesis (FLIE), Work Productivity and Activity Impairment (WPAI:SHP) and MOS SF-12 instruments to assess convergent validity. Analyses included descriptive statistics, classical test theory psychometric analyses and exploratory factor analysis.
RESULTS: A total of 204 subjects [mean age (SD): 41.3 (11.0), 65.7% male; 84.3% white] met eligibility criteria, for which 200 completed the survey and were included in the pre-specified analyses. Of the eligible subjects: 111 (54.4%) experienced nausea alone, and 83 (40.7%) experience both nausea and vomiting. Most subjects (86.8%) had used a GLP-1 for 3 months or less. Response distribution frequencies demonstrated endorsement of all response categories and no evidence of meaningful floor/ceiling effects. All inter-item Spearman correlation coefficients were between r=0.30-0.76. EFA results based on evaluation of the scree plot, factor loadings, and inter-factor correlations, recommended the use of one-factor solution, with all items’ loadings =0.75, supporting a unidimensional total impact score. Internal consistency reliability (Cronbach’s alpha) for the total impact score was a=0.96. Results from construct and known-groups validity were supportive of the pre-specified hypotheses, with most correlations moderate to strong.
CONCLUSIONS: The results from these preliminary psychometric analyses support the use of the NVQ as a reliable and valid measure to assess the impact of nausea and vomiting among T2DM patients who have initiated GLP-1 agonist treatment. Further evaluation in a longitudinal study is needed to assess responsiveness.
