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A novel approach to the use of animals in studies of pain: Development of the Canine Brief Pain Inventory (CBPI)
Dorothy Cimino Brown, DVM, MSCE1, Raymond Boston, MSc, PhD1, James C. Coyne, PhD2, and John T. Farrar, MD, PhD3. (1) School of Veterinary Medicine, University of Pennsylvania, 3900 Delancey Street, Philadelphia, PA 19104-6010, (2) Abramson Cancer Center, University of Pennsylvania, 421 Curie Blvd., Philadelphia, PA 19104-6160, (3) Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, 423 Guardian Drive, Philadelphia, PA 19104-6021
Novel compounds for chronic pain that appear promising in laboratory animals often fail to prove efficacious in clinical trials, suggesting a need for more predictive animal models. The spontaneous pain caused by naturally occurring diseases in companion animals (pets) requires treatment, and the study of novel therapies in these animals can provide greater insight into the potential efficacy in humans. Studies of novel analgesics in companion dogs that spontaneously develop bone cancer reveal drug effects which are not evident in rodent studies. The development of outcome pain measures for use in companion dogs that specifically correspond with outcomes routinely used in clinical research could further increase the predictive capability of these preclinical companion animal studies. The objective of this study was to develop the Canine Brief Pain Inventory (CBPI), based on the human Brief Pain Inventory (BPI), for use in the canine model of spontaneous bone cancer. The item structure, response scaling, and severity items of the BPI were maintained for the CBPI. Impact items were generated through focus groups and an expert panel; poorly performing items were removed; with the reduced set of items subject to factor analysis, reliability, and validity testing. The “severity” and “impact” factors hypothesized based on the BPI were demonstrated in the CBPI. Internal consistency of both factors was high (Cronbach's alpha 0.95 and 0.93), as was test-retest reliability (kappa 0.73 and 0.65). Extreme groups validation against normal dogs showed significantly higher factor scores (P<0.001 for both) and convergent validity was demonstrated against quality of life (r=0.49 and 0.63). The CBPI and BPI reliably measure the same pain constructs in comparable diseases. This innovative approach to preclinical outcomes development applied to companion animals with complex behaviors and clear parallels to human disease pathogenesis, progression and symptomatology, could transform the predictive ability of preclinical pain studies.