This research project is an observational cohort study, representing a secondary analysis of multicenter prospective data from China spanning 2020 to 2022. The study aims to investigate the impact of moderate to severe acute pain on the first postoperative day (POD1) on delirium and anxiety and depression states in elderly patients undergoing abdominal surgery.

Post operative delirium will be diagnosed using the 3D- CAM(Confusion Assessment Method) which tests for four features with a series of questions. The features include 1) acute onset and fluctuating course,2) inattention,3) disorganized thinking and 4) altered level of consciousness. Diagnosis of delirium is made if features 1 and 2 and either 3 or 4 are present. the investigators collected baseline characteristics and demographic data of the patients, including clinical information in the following areas:(1) Baseline characteristics: age, gender, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status score, smoke, alcohol , preoperative history of chronic pain, and comorbidities (hypertension, diabetes mellitus, coronary artery disease, cerebrovascular disease, hepatic insufficiency, and renal insufficiency).(2) Preoperative laboratory tests (the most recent prior to surgery): hemoglobin (Hb), white blood cell count, and serum albumin.(3) Preoperative psychological assessments: anxiety and depression state evaluations.(4) Intraoperative variables: grade of operation, type of surgery, duration of surgery, blood transfusion, blood loss, intraoperative dexmedetomidine and nonsteroidal anti-inflammatory drugs (NSAIDs), drain, and PCIA.In this study, the investigators defined the presence or absence of moderate-to-severe pain on POD1 as the exposure variable, assessed using the Numerical Rating Scale (NRS). An NRS score <4 on POD1 was classified as mild pain, while a score ≥4 indicated moderate-to-severe pain 8. Based on this exposure variable, patients were stratified into two groups: the mild pain group (NRS <4) and the moderate-to-severe pain group (NRS ≥4).The investigators summarized patient characteristics based on the presence or absence of moderate-to-severe pain. Continuous variables were expressed as mean ± standard deviation or median (interquartile range) and compared using t-tests or Mann-Whitney U tests. Categorical variables were presented as frequencies and percentages and compared using chi-square tests. Univariate and multivariate regression models were employed to examine the relationship between early postoperative acute pain and the incidence of POD . Furthermore, propensity score matching and subgroup analyses were conducted to further explore the association between the two.

Inclusion Criteria:

1. ≥65 years;
2. Absence of hearing, visual, or cognitive impairments (operationally defined as a Chinese version of the Mini-Mental State Examination [MMSE] score ≤17);
3. Scheduled for elective abdominal surgery;
4. Under general anesthesia with endotracheal intubation;
5. Completion of postoperative delirium, anxiety, and depression assessments.

Exclusion Criteria:

1. History of severe psychiatric disorders or chronic use of psychotropic medications;
2. Surgery performed via natural orifice transluminal endoscopic surgery (NOTES) approach;
3. Undergoing vascular interventional procedures;postoperative transfer to the intensive care unit (ICU);
4. Death within 7 days after surgery. -

Elderly patients (≥65 years) scheduled for elective abdominal surgery under general anesthesia with endotracheal intubation, without hearing, visual, or cognitive impairments, who completed assessments for postoperative delirium, anxiety, and depression.