Pain Trajectories in Severe Persistent Inguinal Post-herniorrhaphy Pain

Severe persistent post-surgical pain (PPP) is a prevalent medical problem leading to impairment of physical and psycho-social functions in a large number of individuals.Severe PPP may significantly influence 4-8% of the surgical population, depending primarily on the surgical procedure and technique, but also patient-related pre-surgical factors.Updated criteria for PPP have recently been suggested. Inguinal herniorrhaphy qualifies for PPP-research due to a high surgical volume. Paradoxically, while the surgery is considered a minor procedure with limited tissue damage it is carried out in a territory with abundant nerve and vascular supply, and, complex musculoskeletal functions essential for locomotor actions. Persistent pain after inguinal herniorrhaphy may develop after a seemingly successful surgical procedure, and, is seen in a severe form in 2-4% of the patients associated with significant deterioration of the health-related quality of life.

The transition process from acute to persistent pain may be more complex than previously assumed, making the study of temporal pain trajectories interesting. Based on clinical experience from a nationwide research center in PPP following inguinal herniorrhaphy, the authors decided first, to perform a prospective exploratory cohort study examining graphical pain charts by planimetrics, attempting to construct a valid statistical sub-classification of the trajectories. Secondly, the relationship between the sub-classification of the trajectories, and, potential explanatory variables, based on individual profiles of pain, psychometrics, quantitative sensory testing, and surgical procedures, were analysed, using principal component analysis and logistic regression models.