In veterinary clinical pain studies, there is a paucity of data on test-retest variability in Clinical Metrology Instruments (CMIs), and it is unknown whether CMIs should be administered using independent (respondents not permitted to see previous answers) or dependent (respondents shown previous answers) interviewing.
To compare baseline variability in CMIs designed to assess pain in dogs with osteoarthritis, and compare CMI scores using independent (InD) and dependent interviewing (DI) for the Canine Brief Pain Inventory (CBPI) and the Client-Specific Outcome Measures (CSOM).
Fifty-one client-owned dogs with radiographic evidence of osteoarthritis and associated pain.
Clinical Metrology Instruments data were collected during 2 randomized, double-masked, placebo-controlled, proof of principle pilot studies with parallel treatment groups. Enrolled dogs received either placebo or antinerve growth factor antibody (NV-01).
Agreement between baseline CMI scores was good (CBPI Pain P = .29, CBPI Interference P = .32, CSOM P = .036, LOAD P = .67, HCPI P = .27), being best for the LOAD (ICC = 0.89). CMI responses collected during independent and dependent interviewing were not statistically different (CBPI Pain P = .33, CBPI Interference P = .28, CSOM P = .42) and showed good agreement. Additionally, dependent interviewing resulted in increased treatment effect sizes.
There is little difference between independent and dependent interviewing, however, dependent interviewing resulted in increased treatment effect sizes. By using dependent interviewing, investigators could increase clinical trial power through minimal change to study design. Further research is warranted to investigate the use of dependent interviewing.