Recognizing pain phenotypes: biopsychosocial sources of variability in the transition to chronic postsurgical pain.

Chronic postsurgical pain (CPSP) is a cause of new chronic pain, with a wide range of reported incidence. Previous longitudinal studies suggest that development of CPSP may depend more on the constellation of risk factors around a patient (pre-existing pain phenotype) rather than on the extent of surgical injury itself. The biopsychosocial model of pain outlines a broad array of factors that modulate the severity, longevity, and impact of pain. Biological variables associated with CPSP include age, sex, baseline pain sensitivity, and opioid tolerance. Psychological factors, including anxiety, depression, somatization, sleep disturbance, catastrophizing, and resilience, and social factors, like education and social support, may also importantly modulate CPSP. Prevention efforts have targeted acute pain reduction using multimodal analgesia (regional anesthesia and intraoperative analgesic adjuvant medications). However, studies that do not measure or take phenotypic risk factors into account (either using them for enrichment or statistically as effect modifiers) likely suffer from underpowering, and thus, fail to discern subgroups of patients that preventive measures may be most helpful to. Early preoperative identification of a patient's pain phenotype allows estimation of their constellation of risk factors and may greatly enhance successful, personalized prevention of postoperative pain. Effective preoperative employment of behavioral interventions like cognitive-behavioral therapy, stress reduction, and physical and mental prehabilitation may particularly require knowledge of a patient's pain phenotype. Preoperative assessment of patients' pain phenotypes will not only inform high-quality personalized perioperative care clinically, but it will enable enriched testing of novel therapies in future scientific studies.