Pain versus Nociception
A frequently seen phenomenon is that the pain scores a patient reports seem to have little to do with the severity of the trauma or the extent of the surgery the patient experienced. Reported and experienced pain frequently does not reflect the extent of the tissue damage or potential tissue injury caused by trauma, surgery or an inflammatory process. It is important to understand that the perception of pain and nociceptive input, the ‘pain signaling’ that is caused when painful stimuli activate nociceptors, are linked but are very different processes.
Pain is a subjective and multidimensional experience that is modulated by various factors. It is in fact a highly processed signal.
Predictors of Acute Pain after Surgery
A systematic review of 48 studies with 23,037 patients investigating the independent risk factors for pain after surgery identified the following predictors of acute pain after surgery 1:
- Type of surgery: The type of surgery is non-surprisingly found to be a strong predictor for both postoperative pain and analgesic consumption. The most painful operations are orthopedic surgery with major joints surgery, thoracic, and open abdominal surgery.
- Preexisting pain: Often underappreciated, preexisting pain, chronic pain, and low preoperative pain thresholds have a strong predictive value for postoperative pain.
- Anxiety: Psychosocial and behavioral factors such as anxiety and catastrophizing have been identified as very strong predictors of postoperative pain.
- Age: Younger age has been associated with more postoperative pain and increased needs for pain medication.
Other factors frequently associated with more challenging pain control after surgery (but with less data supporting their role), are female gender, history of substance use disorder, and preoperative opioid use.
In addition, there is evidence that our genetic make up may be responsible for the extent of our pain: genetic polymorphisms have been correlated with altered pain perception and processing. 2