To gain a clearer understanding of the association between frailty and postoperative acute pain in elderly thoracoscopic surgery patients and its underlying mechanisms, to provide new solution ideas to reduce the level of postoperative acute pain and improve the debilitating state of elderly thoracoscopic surgery patients, and consequently improve their quality of life and mental status.

Frailty, as a geriatric syndrome, is recognized as being characterized by a decline in the reserve capacity of the body's physiological systems1 and, in severe cases, by regulatory disorders, which result in a decrease in the individual's resistance and resilience to a variety of contingency sources, including organismal, physiological, and psychological stressors as well as an increase in organismal susceptibility to damage. The globe is accelerating its entry into an aging society, and, according to the World Health Organization's report on aging and health reports, the proportion of the world's population over the age of 60 will increase from 12% to 22% between 2015 and 2050. As the population ages, the prevalence of frailty in healthy populations increases exponentially with age. The prevalence in healthy populations ranges from 6.5% in healthy people between the ages of 60-69 years to as high as 65% or even higher in healthy people over the age of 85 years. The prevalence of frailty in healthy populations has been shown to increase with age.

Frailty is now an emerging global health burden, with a meta-analysis of studies from 62 countries noting a 24% prevalence of frailty and a 49% prevalence of pre-frailty in people over the age of 50. Frailty typically prolongs hospital stays and increases hospitalization costs for older patients, increases the prevalence of depression and the risk of cardiovascular disease, increases intraoperative blood loss in patients, and even leads to an increased risk of new-onset disability and death in individuals. Frailty has been shown to increase the risk of new-onset disability, death in individuals, and intraoperative blood loss in patients. Frailty can even lead to an increased risk of new-onset disability and death in individuals.

Currently, the proportion of elderly patients undergoing surgery is also increasing. With the development of minimally invasive surgery, more and more thoracic surgical diseases are treated with thoracoscopic surgery, which is characterized by smaller incisions, less trauma, better results, and the promotion of rapid recovery, compared with open thoracic surgery. Despite the rapid and minimally invasive development of thoracic surgery, postoperative pain after lung surgery is severe, and patients in the first few hours after surgery may still experience severe pain. Postoperative pain can lead to adverse consequences such as decreased quality of life and impact on physical and mental health. Some studies have shown that older adults with early-onset debility have a high prevalence of chronic pain, and risk factors for the development of debility include the prolonged presence of pain. Thus, there may be an unproven bidirectional relationship between debility and pain.

Currently, the mechanisms of the development of frailty are unknown, and Frailty is associated with gut microbiota and biomarkers. Therefore, a clear understanding of the association between frailty and acute postoperative pain in elderly thoracoscopic surgery patients and its underlying mechanisms is essential to reduce the level of acute postoperative pain and improve the frailty status of elderly thoracoscopic surgery patients, but also important to improve their quality of life and mental status.

Inclusion Criteria:

1. patients undergoing thoracic surgery under general anesthesia with 48 h of postoperative patient-controlled analgesia;
2. age ≥60 years;
3. ASA class I-III;
4. signed informed consent;
5. patients undergoing thoracoscopic surgery.

Exclusion Criteria:

1. Patients who themselves refuse to participate in the study;
2. Drug dependence;
3. Patients who cannot cooperate with communication and have verbal communication difficulties;
4. Patients who cannot assess frailty preoperatively and pain postoperatively;
5. Failure to provide a compliant fecal sample at the agreed time;
6. antibiotic treatment within the last month;
7. intestinal dysfunction (e.g., irritable bowel syndrome, inflammatory bowel disease, chronic diarrhea, and other types of intestinal disorders);
8. comorbidities of certain metabolic disorders (e.g., thyroid dysfunction, diabetes mellitus, and so on) that may affect the structure of the microbial community;

It is proposed to observe cases with age greater than or equal to 60 years undergoing thoracoscopic surgery at Tongji Hospital from February 2024 to October 2024 who meet the inclusion and exclusion criteria.