Validation of the Short Form of the Brief Pain Inventory (BPI-SF) in Spanish Patients with Non-Cancer-Related Pain

The Brief Pain Inventory (BPI) is a widely used pain measurement tool. There are 2 versions, the BPI Long Form (BPI-LF) and Short Form (BPI-SF), which share 2 core scales measuring pain severity and pain interference but which use different recall periods (24hours vs. 1week). To date, the BPI-SF has not been validated for use in Spain. This study investigated the psychometric properties of the BPI-SF Spanish version and compared results on the core scales between BPI-LF and BPI-SF. The data came from a 3-month observational study of 3,029 nononcologic patients managed in Spanish pain units. The BPI-SF's reliability, validity, and responsiveness were assessed. The effect of different recall periods was investigated by using intraclass correlation coefficients (ICCs) to determine the strength of correlation between BPI-LF and BPI-SF. The BPI-SF showed good reliability, with Cronbach's alphas of 0.931 for the severity and interference scales, which also discriminated well between patients reporting different levels of quality of life on EuroQol-5D dimensions (between group effect sizes [ESs] over 0.8). Substantial improvements were seen on both subscales after 3months of treatment (ES of 1.76 for pain severity and 1.51 for pain interference). Recall period did not noticeably affect scores; ICCs (95% CI) between the long and short versions were 0.946 (0.938 to 0.954) and 0.929 (0.919 to 0.939) for the severity and interference subscales, respectively. The Spanish version of the BPI-SF is a valid and reliable instrument to measure pain severity and interference.