The Italian Questionnaire for Cancer Breakthrough Pain Diagnosis, a Multicenter Validation Study

Introduction The literature lacks formally validated and reliable tools for the diagnosis of breakthrough cancer pain (BTcP). The Italian Questionnaire for BTcP diagnosis (IQ-BTP) is an 11-item questionnaire aimed at detecting potential-BTP and classifying it into three likelihood classes: high, intermediate, and low. Methods A multicenter, prospective, and observational study was designed to validate the IQ-BTP. In three consecutive visits with each cancer patient, the demographic and clinical details of the patient, the Brief Pain Inventory (BPI) scores, IQ-BTP outcomes, and clinicians' autonomous BTcP diagnosis (gold standard) and the agreement of this diagnosis with IQ-BTP outcomes were recorded. The assessed domains for IQ-BTP validation were: Validity, including content and face validity, construct validity (hypothesis testing, and cross‐cultural validity\measurement invariance), and criterion validity; Reliability (internal consistency, reliability, and measurement error); Interpretability, and Responsiveness. Results Seven palliative and pain management facilities in Italy recruited 280 patients, yielding 753 evaluations. Using the IQ-BTP, the rate of potential-BTcP was 27.2%, of which its likely presence was high in 52.7% of patients, intermediate in 38.5, and low in 8.8%. The BPI item scores differed significantly between the two IQ-BTP classes (no-BTcP and potential-BTcP classes). The correlation of the latter class with BPI items was significant but low. The IQ-BTcP showed two principal components, accounting for 66.6% of the variance. Cronbach’s α was 0.71. The agreement rate between the gold standard and IQ-BTP outcomes was 82%. Cohen's \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\kappa$$\end{document}κ was 0.535. The IQ-BTP showed sensitivity and specificity of 69 and 86%, respectively. Conclusions The IQ-BTP extensive formal validation showed satisfactory psychometric and validity properties. Its content, face, construct, and criterion validities and its reliability, interpretability, and responsiveness were shown. Its use enabled potential-BTcP to be identified and differentiated into three likelihood classes with direct therapeutic and epidemiological implications. The latter may be confirmed in future studies. Supplementary Information The online version contains supplementary material available at 10.1007/s40122-021-00274-9.