This randomized crossover trial compared the practicality of the novel BTS and BPI for evaluating cancer-related pain. The results showed positive correlations of BTS with BPI in pain assessment. In addition, BTS was associated with reduced filling time, greater convenience, and more favorable patient preference. In addition, BTS could help identify breakthrough pain and neuropathic pain.

Currently, the most commonly used scales for evaluating pain in patients include NRS, VAS, and BPI. NRS is measured on a 0–10 scale, with 0 indicating no pain, and 1–3, 4–6, and 7–10 indicating mild, moderate, and severe pain, respectively [15]. BPI is one of the most widely used multidimensional pain assessment tools, primarily assessing pain intensity, nature, and impact on daily life functions [14]. Previous studies compared the results of different pain assessment scales. Brunelli et al. [20] conducted a multicenter cross-sectional study involving 240 cancer patients and found that NRS was more appropriate than the verbal rating scale for assessing worsening of tumor pain. Robinson et al. [21], in an analysis of two international phase II clinical trials, demonstrated that pain intensity assessment using BPI and Functional Assessment of Cancer Therapy–Prostate Cancer was superior to the Present Pain Intensity Index in patients with advanced prostate cancer.

This study employed two pain assessment scales, NRS and BPI, both of which use the 0–10 scale with proof of confirmed effectiveness in previous studies [14, 15, 20, 23, 24]. While NRS uses a single evaluation, BPI comprises of four related questions for assessment of pain intensity. NRS score in BTS was consistent with the worst and the average pain scores within 24 h in BPI, but not with the other two pain scores. This could be attributed to individual bias in the participants' comprehension of each question and subjective perception of pain intensity when responding to the four questions in the BPI evaluation. Nevertheless, significant positive correlations were observed between the NRS pain score in BTS and all four pain intensity indicators in BPI.

Digital tools have become increasingly popular for disease screening and evaluation, owing to their convenience and the ability to create continuous records that can be easily compiled, tracked, and exported in various formats. Researchers have explored the use of digital tools across various disease fields [25,26,27,28,29]. For instance, Chan et al. [25] demonstrated the potential of electronic cognitive screening tools in identifying patients with mild cognitive impairment and Alzheimer's disease. Modasia et al. [26] showed that using disease severity assessment tools on mobile apps and web pages not only saved time and cost but also provided a more user-friendly solution for patients with dermatitis. In our study, while the BTS performed better in terms of filling time, convenience, and patient preference, we acknowledge that the differences between BTS and BPI in terms of convenience and patient preference were less than one point. Future studies with a larger sample size and repeated measurements might be needed to fully assess if these differences are practically significant. Currently, paper pain assessment scales are commonly used in clinical practice, which are less conducive to observing dynamic changes and require large manual workloads to transfer into electronic databases. To address these issues, our digital scale enables patients to directly scan a code on their mobile phones to complete the questionnaires, making it highly convenient, while simplifying data storage and retrieval.

Compared to BPI, BTS enhances the assessment of neuropathic pain and breakthrough pain. A previous study utilized visual descriptions of body parts for neuropathic pain evaluation, which was well regarded by physicians and patients [30]. In our study, we adopted the ID Pain scale for neuropathic pain assessment, as it is concise and easy to use, making it ideal for rapid screening. ID Pain comprises six options: five sensory description options (needling, burning, numbness, electric shock, and hyperalgesia) and one joint pain description option, with a total score ranging from − 1 to 5. A total score of ≥ 2 serves as the judgment criterion for neuropathic pain. Additionally, BTS includes the assessment of breakthrough pain, with the questionnaire using the description of sudden, brief, or unbearable severe pain occurring during the period when pain was already under control with analgesics. During the study, relevant diagnostic information was also collected on past neuropathic pain and breakthrough pain obtained by attending physicians during consultations, which served as the gold standard to evaluate the accuracy of this digital assessment tool. The results showed that the accuracy of BTS in detecting breakthrough pain and neuropathic pain was 98.28% (229/233) and 97.42% (227/233), respectively, indicating that the BTS assessment tool could effectively alert healthcare professionals to the presence of breakthrough and neuropathic pain in patients. This digital assessment tool has potential for wide-spreading clinical application in the future.

This study had limitations. The items in BTS were based on expert consensus, combining NRS, several items of BPI, and the ID Pain scale that have been used in clinical practice, without validation of strict scale development processes. Furthermore, as an exploratory study, sample size was determined based on existing research methodology with similar design, but not strictly performed according to statistical principles. Larger studies with more rigorous designs are necessary to confirm our findings. In addition, although we strived to lessen the burden on patients, the lack of a standard time interval between the two assessments might have had some bearing on the results. Another limitation was the use of a single assessment for both BTS and BPI. We deemed that repeating the assessment within the same day might not add significant value, as the results were likely to be consistent. Additionally, the NRS used in BTS is a well-established and widely used tool, thus we did not plan for repetitive assessments. Finally, prior diagnoses of neuropathic pain and breakthrough pain were obtained from patients’ medical records or face-to-face consultations, and we did not have detailed knowledge of the scales used in these prior evaluations. There may have been cases where patients experienced neuropathic or breakthrough pain, but, without a formal consultation, these might not have been officially diagnosed.