Validation is a logical, step-wise process that investigates and refines the instrument that is being used to measure the outcome. Validation of the measurement instrument gives the investigators, and the users of the research, greater confidence in the results; it also allows easier comparison to other studies since the measurement tool is standardised.
For orthopaedic conditions, one might measure the efficacy of the intervention through analysing how the patient can move, or how the bones or joints look on medical imaging such as X-rays or CT scans, or by asking the patient what they think of the result. Asking the patient is becoming a very accepted method in human medicine and validated patient questionnaires are used to do this, so-called Patient-Reported Outcomes Measures (PROMs). In veterinary medicine, we’d also like to ask the patient but unfortunately, that is not possible, so we use a proxy, the pet owner. Although this is one step removed from the patient, multiple studies now demonstrate the validity of such an approach. There are also parallels in human medicine in areas such as paediatrics and dementia when a parent or carer may respond as the patient’s proxy. So instead of PROMs, we use the term Client-Reported Outcomes Measures (CROMs).
In the RCVS Knowledge Canine Cruciate Registry, we use two validated CROMs specifically developed to assess outcome in canine orthopaedics. These are the ‘Liverpool Osteoarthritis in Dogs’ instrument [1, 2], developed at the University of Liverpool, and the Canine Orthopedic Index [3-5], developed by the American College of Veterinary Surgeons.
The questions in these instruments have been tested for reliability and responsiveness so that we get the best information we can from pet owners regarding the status of their dog. Owners are asked to complete the questionnaire before surgery, and then again at multiple points afterwards. The answers to the questions are then compared to assess the progress of the patient.
We are grateful to Elanco, the University of Liverpool and the American College of Veterinary Surgeons for allowing us to use these questionnaires in this project.
1. Walton, M.B., et al., Evaluation of Construct and Criterion Validity for the ‘Liverpool Osteoarthritis in Dogs’ (LOAD) Clinical Metrology Instrument and Comparison to Two Other Instruments. Plos One, 2013. 8(3).
2. Hercock, C.A., et al., Validation of a client-based clinical metrology instrument for the evaluation of canine elbow osteoarthritis. Journal of Small Animal Practice, 2009. 50(6): p. 266-271.
3. Brown, D.C., The Canine Orthopedic Index. Step 1: Devising the Items. Veterinary Surgery, 2014. 43(3): p. 232-240.
4. Brown, D.C., The Canine Orthopedic Index. Step 2: Psychometric Testing. Veterinary Surgery, 2014. 43(3): p. 241-246.
5. Brown, D.C., The Canine Orthopedic Index. Step 3: Responsiveness Testing. Veterinary Surgery, 2014. 43(3): p. 247-254.