• Chronic Post-Surgical Pain

Chronic pain is the silent epidemic of our times. It is estimated that its economic cost reaches 300 billion euros in Europe, more than other conditions such as cardiovascular diseases, cancer, and diabetes.

Chronic Post-Surgical Pain (CPSP) represents a significant factor in this cost. Its relevance becomes evident when considering that in a context of exponential growth in surgical activity, with over 300 million surgeries performed worldwide annually, 12% of operated patients report moderate to severe pain that limits their functional capacity one year after surgery.

Furthermore, its misdiagnosis results in a social issue, as it leads to inappropriate and unsatisfactory medical therapies that expose patients to a higher risk of opioid addiction.

The incidence of CPSP varies from 5% to 85% depending on the type of surgery. This variability is due to both methodological differences and the late introduction of a standardized definition of CPSP. In order to standardize scientific research, in 2018, the International Association for the Study of Pain (IASP) introduced CPSP for the first time in the eleventh edition of the International Classification of Diseases (ICD-11), defining its characteristics and specific subclasses for each high-risk surgical procedure.

CPSP is defined as the pain that arises or increases in intensity after a surgical procedure and persists beyond the physiological healing processes for at least 3 months following the triggering event. In the absence of other causes such as trauma, infections, or malignant tumors, postoperative pain exists when it is localized in the surgical area, projects into the innervation territory of a nerve in that area, or into the corresponding dermatome in the case of visceral or deep somatic surgery. It can quickly exhibit neuropathic pain characteristics; therefore, neuropathic pain that occurs in an area of interest after surgery should be defined as postoperative pain.

CPSP is contributed to by both iatrogenic injuries and central sensitization processes. High-risk surgeries for which IASP has introduced specific CPSP definitions include amputation surgeries, thoracotomy, breast surgery, hip and knee arthroplasty, hysterectomy, and inguinal and femoral herniotomy. Other factors that have been shown to promote CPSP are young age, female sex, high body mass index, preoperative pain, severe acute postoperative pain, perioperative opioid use, and negative emotional states such as anxiety, depression, and pain catastrophizing.

Numerous pharmacological studies have investigated the effects of preventive strategies in the development of CPSP. However, as demonstrated by recent meta-analyses, the results are disappointing. The only intuitive conclusion is to prevent pain sensitization by reducing the intensity of acute pain, adopting multimodal analgesia strategies that include loco-regional anesthesia techniques and limiting the use of opioids before and during surgery.

The response to the costly tragedy of CPSP came only in 2014 when Toronto General Hospital first launched the Transitional Pain Service, an innovative multidisciplinary approach based on the early identification of patients at risk of CPSP and their perioperative follow-up for up to 6 months after hospital discharge.

The Transitional Pain Service (TDS) team includes anesthesiologists, nurses, psychologists, palliative care specialists, physiotherapists, and a coordinator. The services offered are divided into three categories: Introduction and optimization of multimodal analgesia to improve pain management and facilitate opioid withdrawal; Non-pharmacological interventions, including physiotherapy and acupuncture; Psychological interventions based on acceptance and commitment therapy (ACT) models.

The main goal of this work is to apply the new definition proposed by IASP to study the incidence of CPSP in the case of patients operated at the Dexeus University Hospital in Barcelona. Other objectives are to estimate a predictive model for the development of post-surgical chronic pain, understand its characteristics, describe the analgesic strategies used, and assess the utility of a Transitional Pain Service.

We propose a prospective study in which 171 people over the age of 18 who undergo high-risk CPSP surgeries will be enrolled to estimate a prevalence of approximately 12% with 95% reliability. Candidates will be monitored for three months of postoperative follow-up to assess the incidence of pain, describe its characteristics, and analyze possible predictors of chronicization.

In conclusion, although the establishment of a Transitional Pain Service may still be in its early stages, contributing to a better understanding of Post-Surgical Chronic Pain is crucial. Even small advancements in chronic pain prevention can yield significant health, social, and economic benefits.