Our minds are powerful. Our thoughts and expectations shape our future experiences. As we learn more about pain, we have come to understand the experience of pain is complex.
This review - a research paper pulling many studies on a single topic - showcases the difficulty of predicting pain.
There are many factors influencing the pain experience. Pain predictions also change with knowledge of results. Some patients will overpredict pain prior to a task initially, especially if they are fearful of the task, and once they realize they overpredicted, they underpredict subsequent ratings.
Greater variability is seen in patients with high anxiety compared to low anxiety. Patients with high anxiety overpredicted pain after multiple treatments but the accuracy improved.
Other studies show increases in future pain prediction when underpredicting an initial unknown response (healthy subjects given electric shocks). The spontaneous mismatch and underprediction lead to increased fear of future shocks and subsequent over predictions. The simple act of a clinician or researcher asking a patient their pain rating can influence the outcomes of an intervention.
This ties into the poor reliability of current pain ratings, not just future ones.
The reliability of pain reports is questionable. Descriptors and locations are variable and provide poor diagnostic utility, particularly in chronic pain. That does not mean reports of pain are useless, however.
One study assessing self-reported musculoskeletal pain showed that reporting a single pain site or none at all is rare; nearly two out of five individuals reported pain from at least five sites. There is a strong and linear relationship between the number of pain sites and functional ability. The number of pain sites is a strong predictor for future disability, up to 14 years later.
It is common for patients in healthcare settings to report other symptoms in addition to pain. A recent research study assessed the relationship between self-reported non-musculoskeletal symptoms and musculoskeletal pain.
Study participants were asked to report whether they had experienced pain or discomfort in any of ten different body regions during the last 7 days: head, neck, shoulder, elbow, hand/wrist, upper back, lower back, hip, knee, and ankle/foot. They were asked to report non-musculoskeletal symptoms as well. They included palpitations/extra heartbeats, chest pain, breathing difficulties, heartburn, stomach discomfort, diarrhea, constipation, eczema, tiredness, dizziness, anxiety, depression, and sleep problems.
A simple correlation analysis showed a strong association between non-MSK symptoms and the number of pain sites.
Pain is complex and there is much still to learn about its presence and influence on us.