Measurement properties of pain scoring instruments in farm animals: A systematic review using the COSMIN checklist

Abstract

This systematic review aimed to investigate the measurement properties of pain scoring instruments in farm animals. According to the PRISMA guidelines, a registered report protocol was previously published in this journal. Studies reporting the development and validation of acute and chronic pain scoring instruments based on behavioral and/or facial expressions of farm animals were searched. Data extraction and assessment were performed individually by two investigators using the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines. Nine categories were assessed: two for scale development (general design requirements and development, and content validity and comprehensibility) and seven for measurement properties (internal consistency, reliability, measurement error, criterion and construct validity, responsiveness and cross-cultural validity). The overall strength of evidence (high, moderate, low, or very low) of each instrument was scored based on methodological quality, number of studies and studies’ findings. Twenty instruments for three species (bovine, ovine and swine) were included. There was considerable variability concerning their development and measurement properties. Three behavior-based instruments scored high for strength of evidence: UCAPS (Unesp-Botucatu Unidimensional Composite Pain Scale for assessing postoperative pain in cattle), USAPS (Unesp-Botucatu Sheep Acute Composite Pain Scale) and UPAPS (Unesp-Botucatu Pig Composite Acute Pain Scale). Four instruments scored moderate for strength of evidence: MPSS (Multidimensional Pain Scoring System for bovine), SPFES (Sheep Pain Facial Expression Scale), LGS (Lamb Grimace Scale) and PGS-B (Piglet Grimace Scale-B). Most instruments (n = 13) scored low or very low for final overall evidence. Construct validity was the most reported measurement property followed by criterion validity and reliability. Instruments with reported validation are urgently required for pain assessment of buffalos, goats, camelids and avian species.

Pain Assessment in Animals: human experts, make way for AI!

“…The dependence on good quality images with two views is one of the most important limitations for this method and pros and cons of in-person or remote automated monitoring have been previously addressed [33]. USAPS uses body behavioral information and is considered a more accurate method than SFPES [65]. Although comparing the machine to USAPS may not be fair, as the machine only has access to frontal and side images, while a human using USAPS observes the animal's behavior over a period of time, Table 1 still shows that the machine outperforms human experts also in this case, although the improvement was not found significant.…”

Effects of assessment method (real-time versus video-recorded) on a validated pain-altered behavior scale used in castrated piglets

“…In a translational biomedical research context, the untreated or under-treated pain may act as a confounding factor in the study contributing to poor quality of data and questioning ethical experimental practices 5 – 7 . As a response to this, objective approaches to assess pain, including the Unesp-Botucatu Pig Composite Acute Pain Scale (UPAPS) are needed to successfully identify and manage pigs experiencing pain 27 – 29 . However, assessing piglet pain has been traditionally conducted using video recordings which is a less practical approach given the logistical/financial challenges of placing video equipment in such settings and ethical concerns regarding the inability to provide real-time medical intervention and rescue analgesia in suffering animals.…”

“…Currently, there are five species-specific pain scales used in swine including the Piglet Grimace Scale 18 – 22 , Sow Grimace Scale 23 , Unesp-Botucatu Pig Composite Acute Pain Scale (UPAPS) 8 , 24 , and two additional behavioral pain scales 25 , 26 . In order to accurately assess pain, tools used must demonstrate a high evidence of validation based on robust scientific guidelines such as the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) 27 . According to these guidelines, the UPAPS represents the most robust assessment tool for measuring pain in pigs as demonstrated by its good repeatability and reproducibility, sensitivity, specificity, responsiveness, and excellent internal consistency.…”

Development and Validation of the Unesp-Botucatu Goat Acute Pain Scale

“…Until recently, the difficulty in recognizing pain in production animals was due to the lack of reliable validated instruments for its assessment, which contributed to oligoanalgesia in certain species [ 5 , 6 , 7 ]. This deficiency has been overcome in some species of production animals, such as cattle [ 8 ], swine [ 9 ], and sheep [ 10 ], but goats are one of the few species of domestic and production animals for which there is not yet a validated species-specific scale.…”

“…For pain scales to be reliable, accurate, and species-specific, they must be assessed using validity and reliability criteria already established in other animal species [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], and that follow international validation guidelines. Considering the lack of validated tools to assess pain in goats, the present study aimed to develop and validate a scale to assess acute pain in goats using a methodology similar to that used in other species of domestic animals and following the guidelines from COSMIN [ 7 , 24 , 25 ].…”