Identifying risk factors for chronic postsurgical pain and preventive measures: a comprehensive update

Incidence, Severity, and Interference of Chronic Postsurgical Pain After Cesarean Delivery: A Systematic Review and Meta-analysis

BACKGROUND

Chronic postsurgical pain (CPSP) is a common complication following surgery. Cesarean delivery (CD) is the most performed inpatient surgery, however, the true incidence of CPSP after CD in contemporary practice is unknown. This systematic review and meta-analysis aimed to determine the incidence and severity of CPSP after CD and assess interference with maternal health-related quality of life (HR-QoL).

METHODS

A 7-database literature search was used to identify observational and randomized controlled studies (RCTs) reporting the incidence of CPSP following CD (published January 2015 to August 2023). Included studies were added to the 29 studies identified from a prior review published in 2016. The primary outcome was incidence of CPSP (wound, scar or abdomen) between ≥3 to <6 months, ≥6 to <12, and ≥ 12 months. Secondary outcomes were incidence of chronic pain (back, pelvis or other residual); pain intensity at rest and movement-evoked, and chronic pain interference with maternal HR-QoL at each time interval.

RESULTS

50 studies involving 13,149 patients were included. Meta-analysis with random-effects model (n = 9228; 9 RCTs and 20 observational) revealed an incidence of scar-specific CPSP of 16.7 % (C·I. 13.1 to 20.4 %; I2 = 97.0 %; p < 0.001) at ≥3 to <6 months, 11.4 % (95 % CI 8.7 to 14.0 %; I2 = 94.1 %; P < 0.001) at ≥6 to <12 months, and 8.8 % (95 % CI 6.6 to 11.0 %; I2 = 97.3 %; P < 0.001) at ≥12 months. Meta-regression analysis using publication year as the co-variate revealed a stable CPSP incidence from 2002 onwards. Between ≥6 to <12 months, 51.2 % (95 % C·I: 18.7 to 83.8 %) and 13.5 % (95 % C·I: 0 to 27.1 %) of women had mild and severe pain at rest, respectively. CPSP interfered with HR-QoL in all 7 subdomains of the Brief Pain Inventory in the majority (>50 %) of patients. Walking ability was impacted in 67.6 % (95 % CI 57.6 to 77.6 %; I2 = 50 %) at ≥3 to <6 months. Normal work was impacted in 69.4 % (95 % CI 59.3 to 79.6 %; I2 = 18.6 %) and enjoyment of life in 79.5 % (67.1 to 91.9 %; I2 = 59.3 %) at ≥6 to <12 months. Therefore an estimated 10 % of patients experience CPSP after CD that interferes with daily life, work, social life and personal care. The GRADE quality of evidence was rated as very low for all outcomes.

CONCLUSIONS

CPSP after CD occurs in 16.7 % of patients at ≥3 to <6 months postpartum and widely interferes with maternal HR-QoL domains in the majority of those affected. Further studies are required to explore potential mitigating factors and optimal treatment strategies.

N-Methyl-D-aspartate receptor antagonists for the prevention of chronic postsurgical pain: a narrative review

The N-methyl-D-aspartate receptor (NMDAR) has been linked to the development of chronic postsurgical pain (CPSP), defined as pain after surgery that does not resolve by 3 months. Once the combination of a painful stimulus and glutamate binding activates the NMDAR, calcium influx triggers signaling cascades that lead to processes like central sensitization and CPSP. Three of the most widely studied perioperative NMDAR antagonists include ketamine, magnesium, and methadone, with ketamine having garnered the greatest amount of attention. While multiple studies have found improved analgesia in the acute postoperative period, fewer studies have focused on long-term outcomes and those that have are often underpowered for CPSP or have not included those patients at highest risk. Existing meta-analyses of ketamine for CPSP are inconsistent in their findings, and studies of magnesium and methadone are even more limited. Overall, the evidence supporting NMDAR antagonists for CPSP is weak and we recommend that future studies focus on high-risk patients and potentially include combinations of NMDAR antagonists administered together for the longest duration feasible. The results of ongoing trials could have a major influence on the overall direction of the evidence supporting NMDAR antagonists in preventing CPSP.

Peripheral blood immunoinflammatory biomarkers: prospective predictors of postoperative long-term survival and chronic postsurgical pain in breast cancer

Background

Tumor progression and chronic postsurgical pain (CPSP) in patients with breast cancer are both significantly influenced by inflammation. The associations between immunoinflammatory biomarkers and long-term survival, as well as CPSP, remain ambiguous. This study examined the predictive value of immunoinflammatory biomarkers for both long-term survival and CPSP.

Methods

Data on the clinicopathological characteristics and perioperative peripheral blood immunoinflammatory biomarkers of 80 patients who underwent breast cancer surgery were retrospectively collected. Optimal cut-off values for preoperative immunoinflammatory biomarkers, including the preoperative systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), neutrophil-to-lymphocyte ratio (NLR), and pan-immune-inflammation value (PIV), were established via receiver operating characteristic (ROC) curves. Kaplan-Meier curves and Cox regression analysis were used to evaluate the relationships between preoperative immunoinflammatory biomarkers and long-term survival. The relationships among the perioperative neutrophil count (NEU), monocyte count (MONO), lymphocyte count (LYM), platelet count (PLT), SII, SIRI, NLR, PIV, dynamic changes in peripheral blood cell counts, and CPSP were further assessed using logistic regression analysis.

Results

Kaplan-Meier curves revealed a considerable prolongation of disease-free survival (DFS) and overall survival (OS) in the low preoperative SII, SIRI, NLR, and PIV groups. Multivariate Cox regression analysis revealed that only an elevated preoperative SIRI was an independent risk factor for postoperative DFS (HR=8.890, P=0.038). The incidence of CPSP was 28.75%. Univariate logistic regression analysis revealed that body mass index (BMI), postoperative NEU, MONO, SIRI, and PIV were negatively correlated with the occurrence of CPSP, whereas subsequent multivariate logistic regression analysis revealed that only BMI was independently associated with CPSP (OR=0.262, P=0.023).

Conclusion

Elevated preoperative SIRI was an independent risk factor for poor DFS in breast cancer patients after surgery. In contrast, perioperative immunoinflammatory biomarkers had limited potential for predicting CPSP in patients who underwent breast cancer surgery.

Impaired Basal Forebrain Cholinergic Neuron GDNF Signaling Contributes to Perioperative Sleep Deprivation-Induced Chronicity of Postsurgical Pain in Mice Through Regulating Cholinergic Neuronal Activity, Apoptosis, and Autophagy

AIMS

This study investigated the roles of lateral basal forebrain glial cell line-derived neurotrophic factor (GDNF) signaling and cholinergic neuron activity, apoptosis, and autophagy dysfunction in sleep deprivation-induced increased risk of chronic postsurgical pain (CPSP) in mice.

METHODS

Sleep deprivation (6 h per day from -1 to 3 days postoperatively) was administered to mice receiving skin/muscle incision and retraction (SMIR) to determine whether perioperative sleep deprivation induces mechanical and thermal pain hypersensitivity, increases the risk of chronic pain, and causes changes of basal forebrain neurons activity (c-Fos immunostaining), apoptosis (cleaved Caspase-3 expression), autophagy (LC3 and p62 expression) and GDNF expression. Adeno-associated virus (AAV)-GDNF was microinjected into the basal forebrain to see whether increased GDNF expression could reverse sleep deprivation-induced changes in pain duration and cholinergic neuron apoptosis and autophagy. Cholinergic neurons were further depleted by mu p75-SAP to examine whether the pain-prolonging effects of sleep deprivation still exist.

RESULTS

Perioperative sleep deprivation enhanced pain sensation and prolonged pain duration in SMIR mice, which was accompanied by decreased cholinergic neuron activity and GDNF expression, increased apoptosis, and autophagy dysfunction in the substantia innominata (SI), magnocellular preoptic nucleus (MCPO), and horizontal diagonal band Broca (HDB) (hereafter lateral basal forebrain). Normalizing cholinergic neuron GDNF expression by AAV-GDNF in the lateral basal forebrain inhibited apoptosis and autophagy dysfunction and mitigated sleep deprivation-induced pain maintenance. Mice with selective lesion of lateral basal forebrain cholinergic neurons were resistant to the pain-enhancing and prolonging effects of sleep deprivation and the pain-alleviating effects of AAV-GDNF therapy.

CONCLUSIONS

Perioperative sleep deprivation promotes chronicity of postsurgical pain possibly through decreasing basal forebrain GDNF signaling and causing cholinergic neuronal apoptosis and autophagy dysfunction.

Hyperbaric Oxygen Attenuates Chronic Postsurgical Pain by Regulating the CD73/Adenosine/A1R Axis of the Spinal Cord in Rats

Chronic postsurgical pain (CPSP) affects postoperative rehabilitation and quality of life in patients, but its mechanisms are still poorly understood. Hyperbaric oxygen (HBO) attenuates neuropathic pain in animal and human studies, but its efficacy for CPSP treatment and its underlying mechanism have not been elucidated. This study aimed to investigate the analgesic effect of HBO in a CPSP rat model and the role of spinal cord adenosine circulation in HBO-induced analgesia. A skin/muscle incision and retraction (SMIR) rat model was used to mimic CPSP, and HBO treatment (2.5 atmospheric absolute, 60 minutes) was administered once daily for 5 consecutive days beginning 3 days after surgery. The role of spinal cord adenosine circulation in HBO-induced analgesia was investigated using β-methylene ADP (a CD73 inhibitor), 8-cyclopentyl-1,3-dipropylxanthine (an A1R antagonist), or an intrathecal injection of adenosine. The mechanical paw withdrawal threshold was determined at different timepoints before and after surgery. The spinal cord adenosine and adenosine triphosphate (ATP) contents were analyzed using high-performance liquid chromatography, and the spinal cord expression of adenosine-1 receptor (A1R), extracellular 5'-nucleotidase (CD73), and adenosine kinase (ADK) was examined by Western blotting and immunofluorescence staining. The results showed that the mechanical paw withdrawal threshold of the ipsilateral hind paw and the adenosine content decreased, and the spinal cord expression of A1R, CD73, and ADK and ATP content increased within 14 days after surgery. HBO treatment alleviated mechanical allodynia, reduced ATP content, and increased adenosine content by activating CD73 but downregulated the spinal cord expression of A1R, CD73, and ADK. Intrathecal adenosine alleviated mechanical allodynia after SMIR and downregulated the spinal cord expression of A1R and CD73, and intrathecal β-methylene ADP or 8-cyclopentyl-1,3-dipropylxanthine attenuated the analgesic effect of HBO treatment on SMIR-induced CPSP. PERSPECTIVE: Spinal cord adenosine is involved in the occurrence and development of CPSP, and HBO treatment alleviates CPSP by regulating adenosine production/metabolism in the spinal cord. Thus, HBO may be employed for the treatment of CPSP with favorable efficacy.

Incidence and risk factors of pain following breast cancer surgery: a retrospective national inpatient sample database study

BACKGROUND

Postoperative pain (PP) is a dynamic process that reflects the complex interplay between symptoms, treatment, and patient experiences, and its intensity is reportedly primarily related to the severity of surgical trauma. However, no large-scale national database-based study has hitherto been conducted to assess the occurrence and features related to PP following breast cancer (BC) surgery.

METHODS

In this retrospective analysis, we screened BC surgery cases between 2015 and 2019 within the National Inpatient Sample (NIS) Database, utilizing the International Classification of Diseases (ICD) 10th edition clinical modification codes. The researchers identified patients who developed PP and compared them to those who did not. Factors associated with PP were then screened: patient demographics (age and race), hospital characteristics (type of insurance, bed size, teaching status, type of admission, location, and hospital area), length of stay (LOS), total cost during hospitalization, inpatient mortality, comorbidities, and perioperative complications. Data were analyzed using descriptive statistics. Multivariate logistic regression analysis was used to determine the independent risk factors for postoperative pain in BC surgery.

RESULTS

39,870 BC surgery cases were identified over a five-year period from 2015 to 2019. The overall occurrence of PP following breast cancer surgery was 6.15% (2,387 cases), with a slight upward trend every year. Significant racial disparities were observed, Whites associated with a higher incidence of PP (P < 0.001). In addition, the incidence of elective admission was 11.96% lower (67.491% vs. 79.451%) than that of patients without PP following breast cancer surgery (P < 0.001). Besides, PP was related to prolonged hospitalization duration (3 vs. 2 days; P < 0.001), and higher total cost ($68,283 vs. $60,036; P < 0.001). Multivariate logistic regression identified breast cancer surgery-independent risk factors for PP, including younger age, non-elective hospital admission, rural hospitals, depression, drug abuse, metastatic cancer, psychoses, weight loss, and chronic pulmonary disease. In addition, postoperative pain for BC was associated with urinary retention, gastrointestinal complications, continuous invasive ventilation, deep vein thrombosis, urinary tract infection, blood transfusion, arrhythmia, and chest pain.

CONCLUSION

Despite the low incidence of postoperative pain in BC surgery cases, it is essential to investigate factors predisposing to PP to allow optimal care management and improve the outcomes of this patient population.

The Efficacy of the Combination of Continuous Femoral Nerve Block and Intravenous Parecoxib on Rehabilitation in Patients Undergoing Total Knee Arthroplasty: A Double-Blind, Randomized Clinical Trial

BACKGROUND AND AIM

The optimal strategy for the management of postoperative pain after total knee arthroplasty (TKA) remains challenging, while its treatment is crucial to increase patients' outcomes. This study aimed to investigate the effects of parecoxib as add-on therapy, in a standard postoperative pain management protocol, represented by the continuous femoral nervous block. We studied its influence on rehabilitation indices and pain scores in patients undergoing TKA.

MATERIAL AND METHODS

This is a single-center, prospective, double-blind, randomized, placebo-controlled trial. All patients were operated with the use of subarachnoid anesthesia, and divided into two groups for postoperative analgesia. Both groups received a continuous femoral nerve block. One of the groups received intravenous parecoxib, while the other received a placebo. The primary investigated outcome was the range of motion (ROM). Recordings were noted at different times postoperatively. Bromage score (BS), visual analog scale (VAS), and the State-Trait Anxiety Inventory (STAI) were also studied.

RESULTS

A total of 90 patients were included and analyzed. ROM was significantly better (p<0.001) and pain scores were significantly lower (p=0.007) in the parecoxib group. No statistically significant difference was found with regard to BS between the two groups. A significant correlation was found between ROM and VAS pain scores at 12 hours (p=0.02), while ROM was inversely correlated with STAI postoperatively.

CONCLUSIONS

The use of intravenous parecoxib is effective in improving rehabilitation indices and provides decreased postoperative pain scores after TKA.