Related Experiment Video
Updated: May 14, 2026
A Quantitative Sensory Testing Paradigm to Obtain Measures of Pain Processing in Patients Undergoing Breast Cancer Surgery
Published on: January 18, 2018
Minimal clinically important differences in the brief pain inventory in patients with bone metastases
Karrie Wong1, Liang Zeng, Liying Zhang
1Rapid Response Radiotherapy Program, Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5, Canada.
Purpose:
The brief pain inventory (BPI) is often used to assess pain and functional interference as a result of pain in cancer patients. Minor improvements or deteriorations in BPI may be statistically significant due to large sample sizes but may not necessarily be clinically relevant. The purpose of this study was to determine the minimal clinically important differences (MCID) in the functional BPI in patients with pain due to bone metastases.
Methods:
BPI scores were collected from patients with painful bone metastases who visited the Rapid Response Radiotherapy Program for palliative radiotherapy. Pain and functional interferences scores were also collected monthly for three months. Patients were categorized into "complete or partial response," "pain progression," and "indeterminate response" based on their pain scores as recommended by the latest consensus definitions. Anchor-based determination of MCIDs of functional interference scores was calculated by determining the difference between the mean follow-up scores and the mean baseline scores for patients from each of the three response groups. Distribution-based estimates were obtained utilizing 0.2, 0.3, and 0.5 standard deviation (SD) effect sizes and the standard error of measurement. The anchor-based method results were compared with the distribution-based method results.
Results:
Statistically significant MCIDs were determined for all of the functional interference items of BPI for patients with "complete or partial response"; whereas, no statistically significant MCIDs in BPI scores could be determined for patients with "pain progression." Some of the functional interference items of BPI had statistically significant MCIDs for patients with "indeterminate response," although these were generally smaller than patients with complete or partial response. Using the distribution-based approach, an effect size of 0.5 SD was the closest estimate for determining the MCID for both patients with complete or partial response and those with indeterminate response.
Conclusions:
The MCIDs determined for pain improvement were rather large, where as statistically significant MCIDs could not be detected for pain deterioration. Knowledge of MCIDs utilizing the BPI will allow physicians to evaluate the impact of treatment (or no treatment) on a patient's functional abilities. Knowledge of MCIDs may allow for sample size determination in future clinical trials.
Insights
Determining the minimal clinically important differences (MCID) for the Brief Pain Inventory (BPI) in cancer patients with bone metastases is crucial. This study found significant MCIDs for pain improvement but not for pain progression, aiding treatment evaluation.
Area of Science:
- Oncology
- Pain Management
- Clinical Trials
Background:
- The Brief Pain Inventory (BPI) assesses pain and functional interference in cancer patients.
- Statistically significant changes in BPI scores may not always reflect clinically meaningful improvements.
- Establishing minimal clinically important differences (MCID) is vital for interpreting BPI results in clinical practice.
Purpose of the Study:
- To determine the MCID for the functional interference items of the BPI in patients experiencing pain due to bone metastases.
- To differentiate between statistically significant and clinically relevant changes in pain and function.
Main Methods:
- Collected BPI scores from patients with painful bone metastases undergoing palliative radiotherapy.
- Categorized patients into response groups (complete/partial response, pain progression, indeterminate) based on pain scores.
- Calculated MCIDs using anchor-based and distribution-based methods, comparing the two approaches.
Main Results:
- Statistically significant MCIDs were found for functional interference items in patients with complete/partial response.
- No statistically significant MCIDs were detected for patients experiencing pain progression.
- Distribution-based estimates (0.5 SD effect size) aligned with anchor-based MCIDs for improved response groups.
Conclusions:
- MCIDs for pain improvement in bone metastases were substantial, while detection of pain deterioration was limited.
- Understanding BPI MCIDs enables physicians to assess treatment impact on patient function.
- MCID data can inform sample size calculations for future clinical trials.
