How do medical students use and understand pain rating scales?
Authors: Zalmay Pardis , Williams Amanda C. de C. 
Published: January 2017

Abstract

Background and aims
Pain is a multidimensional experience that is difficult to describe and to assess. To scale current pain, assessment refers to a maximum level of pain, but little is known about this process. Further, clinicians tend to underestimate patients’ pain, with or without patients’ own reports, and to underestimate to a greater extent with more clinical experience, possibly due to recalibration of a personal pain scale with increasing exposure to severe pain. We sought to determine how medical students rated pain in early years of clinical exposure, and in relation to experience of their own and others’ worst pains.

Methods
An online survey sampled medical students’ rating and description of their own worst pain and of that witnessed in another; also what would cause the maximum level of pain and what behaviours characterised it. Last, they indicated their preference among pain scales.

Results
Thirty-six medical students provided responses, the majority in their first six months of clinical exposure. Students’ own worst pain was rated a mean of 6.7/10 (s.d. 1.6) on a numerical scale; causes were diverse but with many bone fractures. Mean worst pain observed in another was rated 8.6/10 (s.d. 1.4); causes included fractures, gallstones, and sickle cell crises. Another’s worst pain was significantly higher (mean 9.4, s.d. 0.8 vs mean 8.0 s.d. 1.4) when rated after the student’s own pain than before it (presentation order randomised).
We found no effect of clinical exposure on estimation of worst pain in another person, nor was there a personal tendency to rate pain using more or less extreme values. Students expected pain of 10/10 to be presented with many verbal, facial and whole body behaviours, and signs of physiological stress. Collectively, behavioural descriptions were rich and varied, but with many incompatibilities: for instance, between ‘writhing’ and ‘rigidity’ expected in the person with extreme pain. Most students preferred the numerical rating scale over visual analogue and verbal scales.

Conclusions
The study requires replication, particularly for clinical experience, where we found no significant difference in estimation of another’s pain over the first three years of medical students’ clinical exposure, but the comparison was underpowered. Despite no systematic individual difference in using pain ratings, there was a marked effect of rating another’s worst pain higher when the rater had previously rated his/her own worst pain. This suggests anchoring estimate of another’s pain in personal pain experience, and a possible way to mitigate clinicians’ underestimation of patients’ pain.
Medical students’ recognition of the importance of facial expression in indicating another’s pain severity was encouraging, but most students anticipated only a narrow range of behaviours associated with extreme pain, thereby excluding other authentic behaviours.

Implications
Many clinical guidelines mandate regular pain assessment for hospital inpatients, and encourage routine assessment in community and outpatient settings, in order to decide on and monitor treatment. Replication and elaboration of this study could extend our understanding of how clinicians interpret pain scales completed by patients, and how they estimate patients’ pain.