BACKGROUND:Periprosthetic joint infection is the most common cause of early failure after total knee replacement.The current methods of preventing periprosthetic joint infection by improving the surface of the prosthesis have limitations to varying degrees.OBJECTIVE:To construct a coating material that can stably improve the surface of the implant,prevent the initial floating bacterial infection of periprosthetic infection,and regulate the bone transfer function around the implant.METHODS:(1)Material preparation:YGF polypeptide(which promotes bone formation),LL-37 polypeptide(with antibacterial properties)and YGF+LL-37 composite peptide were prepared by Fmoc solid phase peptide synthesis technology.The titanium-based materials were immersed in the three polypeptide solutions for 2 hours to obtain YGF coating,LL-37 coating and composite peptide coating coated titanium sheets.(2)In vitro experiment:Uncoated titanium sheets and coated titanium sheets were co-cultured with Escherichia coli(or Staphylococcus aureus)and the colonies were counted by plate method.MC3T3 cells were inoculated on the surface of uncoated titanium sheet and coated titanium sheet,respectively.Alizarin red staining was used to observe the calcium salt deposition on the surface of the material.Western blot assay was used to detect the protein expression of RUNX2,osteocalcin,osteopontin,and bone morphogenetic protein 2.(3)Animal experiment:24 SD rats were randomly divided into three groups:the blank group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal;the control group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension;the experimental group(n=8)was implanted with composite peptide coated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension.After 5 weeks of implantation,micro-CT examination,hematoxylin-eosin staining and immunohistochemical staining of femur specimens were performed.RESULTS AND CONCLUSION:(1)In vitro experiment:Compared with uncoated titanium sheet and YGF coated titanium sheet,LL-37 coated and composite peptide coated titanium sheet could significantly inhibit the growth and reproduction of Escherichia coli and Staphylococcus aureus.Compared with uncoated titanium sheets and LL-37-coated titanium sheets,YGF-coated and composite peptide-coated titanium sheets could promote calcium salt deposition in osteoblasts and increase the protein expression of RUNX2,osteocalcin,osteopontin and bone morphogenetic protein 2.(2)Animal experiment:Micro-CT test showed that the control group had less bone mass than the blank group and the experimental group.Hematoxylin-eosin staining showed that there was a large amount of fibrous tissue around the nail channel in the control group,only a small amount of tissue fibrosis around the nail channel in the blank group,and only a small amount of tissue fibrosis around the nail channel in the experimental group.Immunohistochemical staining showed that the protein expression of interleukin 1β and tumor necrosis factor α in the control group was higher than that in the blank group and the experimental group,and the expression of osteocalcin,RUNX2 and osteopontin in the experimental group was higher than that in the blank group and the control group.(3)The results show that the titanium-based material coated with YGF+LL-37 composite peptide coating has good antibacterial ability and can promote bone transfer around the implant.

BACKGROUND:Periprosthetic joint infection is the most common cause of early failure after total knee replacement.The current methods of preventing periprosthetic joint infection by improving the surface of the prosthesis have limitations to varying degrees.OBJECTIVE:To construct a coating material that can stably improve the surface of the implant,prevent the initial floating bacterial infection of periprosthetic infection,and regulate the bone transfer function around the implant.METHODS:(1)Material preparation:YGF polypeptide(which promotes bone formation),LL-37 polypeptide(with antibacterial properties)and YGF+LL-37 composite peptide were prepared by Fmoc solid phase peptide synthesis technology.The titanium-based materials were immersed in the three polypeptide solutions for 2 hours to obtain YGF coating,LL-37 coating and composite peptide coating coated titanium sheets.(2)In vitro experiment:Uncoated titanium sheets and coated titanium sheets were co-cultured with Escherichia coli(or Staphylococcus aureus)and the colonies were counted by plate method.MC3T3 cells were inoculated on the surface of uncoated titanium sheet and coated titanium sheet,respectively.Alizarin red staining was used to observe the calcium salt deposition on the surface of the material.Western blot assay was used to detect the protein expression of RUNX2,osteocalcin,osteopontin,and bone morphogenetic protein 2.(3)Animal experiment:24 SD rats were randomly divided into three groups:the blank group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal;the control group(n=8)was implanted with uncoated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension;the experimental group(n=8)was implanted with composite peptide coated titanium nails in the femoral medullary canal+intra-articular injection of Staphylococcus aureus suspension.After 5 weeks of implantation,micro-CT examination,hematoxylin-eosin staining and immunohistochemical staining of femur specimens were performed.RESULTS AND CONCLUSION:(1)In vitro experiment:Compared with uncoated titanium sheet and YGF coated titanium sheet,LL-37 coated and composite peptide coated titanium sheet could significantly inhibit the growth and reproduction of Escherichia coli and Staphylococcus aureus.Compared with uncoated titanium sheets and LL-37-coated titanium sheets,YGF-coated and composite peptide-coated titanium sheets could promote calcium salt deposition in osteoblasts and increase the protein expression of RUNX2,osteocalcin,osteopontin and bone morphogenetic protein 2.(2)Animal experiment:Micro-CT test showed that the control group had less bone mass than the blank group and the experimental group.Hematoxylin-eosin staining showed that there was a large amount of fibrous tissue around the nail channel in the control group,only a small amount of tissue fibrosis around the nail channel in the blank group,and only a small amount of tissue fibrosis around the nail channel in the experimental group.Immunohistochemical staining showed that the protein expression of interleukin 1β and tumor necrosis factor α in the control group was higher than that in the blank group and the experimental group,and the expression of osteocalcin,RUNX2 and osteopontin in the experimental group was higher than that in the blank group and the control group.(3)The results show that the titanium-based material coated with YGF+LL-37 composite peptide coating has good antibacterial ability and can promote bone transfer around the implant.

Objective To evaluate the clinical efficacy and safety of sulbactam-durlobactam in the treatment of pulmonary infection caused by extensively drug-resistant Acinetobacter baumannii (XDR-AB) after liver transplantation. Methods A retrospective analysis was performed on the data of 3 liver transplant recipients admitted to the First Affiliated Hospital of Xi'an Jiaotong University from May to December 2025, who developed postoperative XDR-AB pulmonary infection and received sulbactam-durlobactam-based anti-infective therapy. Clinical data, clinical efficacy, microbiological response, safety and outcomes were analyzed. Results All isolated strains were XDR-AB producing OXA-23 carbapenemase, and in vitro antimicrobial susceptibility testing showed sensitivity to sulbactam-durlobactam. After treatment with sulbactam-durlobactam, all 3 recipients achieved clinical cure and microbiological eradication, with a treatment course of 6-8 days and pathogen clearance time of 3-6 days. Septic shock was effectively controlled in all recipients, who were successfully weaned from mechanical ventilation, and oxygenation index and organ function scores were significantly improved. No definite nephrotoxicity or other severe adverse reactions related to sulbactam-durlobactam were observed during treatment, and the 30-day all-cause fatality was 0. Two critically ill recipients achieved rapid microbiological clearance after combined nebulized phage therapy. Conclusions Sulbactam-durlobactam-based regimen shows favorable efficacy and safety in liver transplant recipients with postoperative XDR-AB pulmonary infection, and has a promising clinical application prospect.

Objective To explore the characteristics of fluid flow within loaded osteons under different boundary conditions.Methods The COMSOL Multiphysics software was used to establish a three-dimensional(3D)finite element model of osteons with different boundary conditions,and the variation rules of pore pressure and flow velocity of osteons under different inner wall pulsating blood pressures and outer wall elastic constraint conditions were analyzed.Results As the pulsatile blood pressure inside the osteon increased from 0 mmHg(1 mmHg=0.133 kPa)to 300 mmHg,the peak pore pressure within the osteon correspondingly increased from 26 kPa to 68 kPa.As the elastic constraint on the outer wall of osteons changed from being completely elastic to completely constrained,the peak pore pressure within osteons increased from 15 kPa to 26 kPa,and the peak flow velocity increased from 0.04 um/s to 0.07 um/s.Conclusions This study reveals the influence laws of changes in boundary conditions such as the pulsatile blood pressure on the inner wall and the elastic constraint on the outer wall of osteons on fluid flow characteristics within loaded osteons.These findings are conducive to a deeper understanding of the mechanical response mechanisms of bone tissues in both physiological and pathological states,and provide an important theoretical basrs for further researches on bone mechanotransduction.

Objective:To explore the prognosis after radical resection for stage Ⅰ gastric cancer and the application value of adjuvant chemotherapy.Methods:The retrospective cohort study was conducted. The clinicopathological data of 3 353 patients with stage Ⅰ gastric cancer who were admitted to Fudan University Shanghai Cancer Center from January 2000 to December 2022 were collected. There were 2 369 males and 984 females, aged 60(range, 21-91) years. All patients underwent radical R 0 resection. Observation indicators: (1) clinicopathological characteristics of patients; (2) influencing factors for postoperative prognosis of patients; (3) prognostic analysis of patients; (4) construction and validation of a predictive model for the efficacy of postoperative adjuvant chemotherapy. Comparison of count data between groups was conducted using the chi-square test. Univariate and multivariate analyses were performed using the Cox proportional hazards regression model. The Kaplan-Meier method was used to calculate survival rates and draw survival curves, and the Log-rank test was used for survival analysis. Based on the multivariate analysis result, a nomogram prediction model was constructed to predict survival benefit. Results:(1) Clinicopatho-logical characteristics of patients. The highly, moderately, and poorly differentiated tumors were observed in 16, 234, 396 cases of 646 patients aged <50 years and 279, 1 617, 811 cases of 2 707 pati-ents aged ≥50 years, respectively, showing a significant difference in degree of tumor differentiation between them ( P<0.05). For 297 patients in stage T1N1M0, cases aged <50 years and ≥50 years were 71 and 226, cases of males and females were 184 and 113, cases with negative and positive vascular invasion were 37 and 260, cases with negative and positive nerve invasion were 275 and 22, cases without and with postoperative adjuvant chemotherapy were 222 and 75, respectively. The above indicators for 678 patients in stage T2N0M0 105, 573, 533, 145, 517, 161, 526, 152, 563, 115, respectively. There were significant differences in the above indicators between the two groups ( P<0.05). (2) Influencing factors for postoperative prognosis of patients. Results of multivariate analysis showed that age ≥50 years, stage T2, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion, carcinoembryonic antigen (CEA) ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for disease-free survival (DFS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=4.600, 1.555, 1.835, 1.362, 1.451, 1.571, 2.134, 95% confidence interval as 2.806-7.541, 1.205-2.006, 1.016-3.314, 1.059-1.753, 1.057-1.993, 1.100-2.243, 1.257-3.625, P<0.05). Age ≥50 years, stage T2, the number of lymph nodes dissected <16, positive vascular invasion, CEA ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for overall survival (OS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=5.208, 1.597, 1.373, 1.520, 1.464, 2.356, 95% confidence interval as 3.028-8.955, 1.231-2.072, 1.060-1.777, 1.099-2.104, 1.004-2.134, 1.385-4.009, P<0.05). Postoperative adjuvant chemotherapy was an independent protective factor for both DFS and OS after surgery for stage I gastric cancer ( hazard ratio=0.361 0.297, 95% confidence interval as 0.177-0.736, 0.131-0.674, P<0.05). (3) Prognostic analysis of patients. According to the results of multi-variate analysis, among 3 353 patients, there were significant differences in 5-year DFS rate and 10-year OS rate between patients aged <50 years and ≥50 years ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in TNM stage ⅠA and ⅠB ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in stage T1N0M0, T1N1M0, T2N0M0 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the highly, moderately, and poorly differentiated tumors ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the number of lymph lodes dissected <16 and ≥16 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with negative and positive vascular invasion ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05), among patients in stage T1N0M0, T1N1M0, T2N0M0 who received no postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T1N1M0, there was no significant difference in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P>0.05).Results of stratified analysis showed that for patients aged ≥ 50 years, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T2N0M0, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients with positive vascular invasion, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). (4) Construction and validation of a predictive model for the efficacy of adjuvant chemotherapy. A nomogram predictive model was constructed based on the multivariate analysis results of OS and used for calculating net benefits and distribution. Among the 3 096 patients without postoperative adjuvant chemotherapy, 1 009 cases had a predicted net benefit of >5%-10%, and 250 patients had a predicted net benefit >10%. The predicted survival analysis further verified that the predicted benefit of adjuvant chemotherapy was consistent with the prognosis of patients. Conclusions:Patients with age ≥50 years, stage T2 tumors, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion have worse survival prognosis postoperative. Postoperative adjuvant chemotherapy provides better prognosis in high-risk patients. Patients in stage T1N1M0 have lower recurrence and survival risks, of whom with 1 metastatic lymph node is more suitable for follow-up rather than postoperative adjuvant chemotherapy.

Objective To explore the characteristics of fluid flow within loaded osteons under different boundary conditions.Methods The COMSOL Multiphysics software was used to establish a three-dimensional(3D)finite element model of osteons with different boundary conditions,and the variation rules of pore pressure and flow velocity of osteons under different inner wall pulsating blood pressures and outer wall elastic constraint conditions were analyzed.Results As the pulsatile blood pressure inside the osteon increased from 0 mmHg(1 mmHg=0.133 kPa)to 300 mmHg,the peak pore pressure within the osteon correspondingly increased from 26 kPa to 68 kPa.As the elastic constraint on the outer wall of osteons changed from being completely elastic to completely constrained,the peak pore pressure within osteons increased from 15 kPa to 26 kPa,and the peak flow velocity increased from 0.04 um/s to 0.07 um/s.Conclusions This study reveals the influence laws of changes in boundary conditions such as the pulsatile blood pressure on the inner wall and the elastic constraint on the outer wall of osteons on fluid flow characteristics within loaded osteons.These findings are conducive to a deeper understanding of the mechanical response mechanisms of bone tissues in both physiological and pathological states,and provide an important theoretical basrs for further researches on bone mechanotransduction.

Objective To explore the factors influencing cognitive frailty in elderly inpatients with chronic heart failure(CHF)during hospitalisation,8 prediction models were developed with various machine learning algorithms to identify the best model as a guidance for medical staff on clinical interventions.Methods Convenience sampling method was used to select 650 elderly CHF inpatients who stayed in our hospital between September 2023 and June 2024 as the study objects in the cross-sectional investigation.A total of 607 patients had completed the study.The patients were divided into a cognitive frailty group and a non-cognitive frailty group according to the presence or absence of cognitive frailty.Variables were initially screened using univariate analysis and stepwise Logistic regression.The total sample was then randomly divided into a training set(n=424)and a testing set(n=183)of a 7:3 ratio.Eight predictive models were created using the algorithms of neural network(NN),k-nearest neighbour(KNN),linear discriminant analysis(LDA),support vector machine(SVM),naive Bayes(NB),logistic regression,decision tree(DT)and random forest(RF)on the training set.The predictive performance of the models was compared using the data of the testing set.Results The prevalence of cognitive frailty in elderly CHF inpatients was 48.3%.Results of Logistic regression showed that age,marital status,education,body mass index,multi-morbidity,nutritional status,medication,frequency of weekly exercise and the living conditions were the key factors(P<0.05).The overall accuracy in classification of the eight predictive models ranged from 0.803 to 0.847,with F1-values of 0.778 to 0.833,precision of 0.848 to 0.897,and recall rate of 0.700 to 0.778.The area under the receiver operating characteristic curve was 0.820 to 0.901.Conclusion Of the eight predictive models,the prediction model created with LDA shows the best performance and prediction in terms of comprehensive prediction metrics,while the prediction model created with NN shows the worst performance in comprehensive prediction.

Objective To explore the factors influencing cognitive frailty in elderly inpatients with chronic heart failure(CHF)during hospitalisation,8 prediction models were developed with various machine learning algorithms to identify the best model as a guidance for medical staff on clinical interventions.Methods Convenience sampling method was used to select 650 elderly CHF inpatients who stayed in our hospital between September 2023 and June 2024 as the study objects in the cross-sectional investigation.A total of 607 patients had completed the study.The patients were divided into a cognitive frailty group and a non-cognitive frailty group according to the presence or absence of cognitive frailty.Variables were initially screened using univariate analysis and stepwise Logistic regression.The total sample was then randomly divided into a training set(n=424)and a testing set(n=183)of a 7:3 ratio.Eight predictive models were created using the algorithms of neural network(NN),k-nearest neighbour(KNN),linear discriminant analysis(LDA),support vector machine(SVM),naive Bayes(NB),logistic regression,decision tree(DT)and random forest(RF)on the training set.The predictive performance of the models was compared using the data of the testing set.Results The prevalence of cognitive frailty in elderly CHF inpatients was 48.3%.Results of Logistic regression showed that age,marital status,education,body mass index,multi-morbidity,nutritional status,medication,frequency of weekly exercise and the living conditions were the key factors(P<0.05).The overall accuracy in classification of the eight predictive models ranged from 0.803 to 0.847,with F1-values of 0.778 to 0.833,precision of 0.848 to 0.897,and recall rate of 0.700 to 0.778.The area under the receiver operating characteristic curve was 0.820 to 0.901.Conclusion Of the eight predictive models,the prediction model created with LDA shows the best performance and prediction in terms of comprehensive prediction metrics,while the prediction model created with NN shows the worst performance in comprehensive prediction.

Objective:To evaluate the efficacy and safety of fecal microbiota transplantation (FMT) for treating functional constipation, analyze the incidence of, and factors that influence, adverse events, and provide scientific evidence for optimizing FMT treatment.Methods:This retrospective, multicenter, single-arm, pre–post real-world study included 1529 patients with functional constipation from four clinical centers. Eligibility criteria comprised meeting the diagnostic criteria for functional constipation, having undergone at least one FMT treatment, complete pre- and post-treatment data available, and age ≥18 years. Patients who had received other interventions affecting gut function within 1 month before treatment and those with severe organic diseases or immune deficiencies were excluded. Applying the above criteria yielded 1529 eligible patients with functional constipation from four medical centers (1405 from the Shanghai Tenth People's Hospital Affiliated to Tongji University, 20 from the Central Hospital of Wuhan, 67 from the Shanxi Bethune Hospital and 37 from the Longgang District People's Hospital of Shenzhen). The study cohort comprised 746 male (48.8%) and 783 female patients (51.2%) of mean age (51.4 ± 17.4) years, mean body mass index (26.4 ± 4.9) kg/m2, and mean duration of disease (15.0 ± 8.3) years. The primary outcomes were the incidence, types, and severity of adverse reactions during treatment, and their impact on patients' quality of life. Secondary outcomes included: (1) the efficacy of FMT in treating constipation. This was assessed based on changes in Patient Assessment of Constipation Symptoms (PAC-SYM) scores, where higher score indicates worse symptom. (2) Subjective satisfaction, evaluated through questionnaires or rating scales, reflecting patients' acceptance of and satisfaction with the treatment, with scores ranging from 1 to 5, where higher scores indicated greater satisfaction. Paired t-tests and Wilcoxon signed-rank tests were used to evaluate changes in symptom scores and biochemical indicators before and after treatment. Logistic regression was performed to analyze factors influencing adverse events, and subgroup analyses to explored differences in efficacy between patient groups.Results:In this cohort of 1529 patients with functional constipation, adverse reactions were primarily mild to moderate (1048/1529,68.5%). They comprised fever in 54 patients (3.5%), dizziness or fatigue in 218 (14.3%), throat discomfort in 806 (52.7%), nausea and vomiting in 166 (10.9%), and abdominal distension or pain in 415 (27.1%). According to multivariate logistic regression analysis, PAC-SYM scores were associated with the rate of adverse reactions, higher scores indicating a lower risk (OR = 0.958, 95% CI: 0.923–0.993, P=0.021). Among the 1529 patients, 274 (17.9%) underwent two or more treatment courses. After one treatment course, the patients' PAC-SYM scores decreased from (37.7 ± 3.2) pre-treatment to (23.7 ± 8.6) (mean difference 14.0 ± 9.1). PAC-SYM scores decreased by (20.7 ± 7.7) after two courses of FMT, and by (19.4 ± 6.3) after three courses. After treatment, 50.7%(775/1529) of patients reported satisfaction scores of ≥4. Adverse reactions impacted satisfaction; specifically, dizziness/fatigue, throat discomfort, and abdominal distension/pain were significantly associated with satisfaction (all P < 0.05). Conclusions:FMT achieved good relief of symptoms of functional constipation and multiple treatment courses have a cumulative effect. Adverse reactions, mainly dizziness/fatigue, throat discomfort, and abdominal distension/pain, had significant negative impacts on patient satisfaction.

Objective:To explore the prognosis after radical resection for stage Ⅰ gastric cancer and the application value of adjuvant chemotherapy.Methods:The retrospective cohort study was conducted. The clinicopathological data of 3 353 patients with stage Ⅰ gastric cancer who were admitted to Fudan University Shanghai Cancer Center from January 2000 to December 2022 were collected. There were 2 369 males and 984 females, aged 60(range, 21-91) years. All patients underwent radical R 0 resection. Observation indicators: (1) clinicopathological characteristics of patients; (2) influencing factors for postoperative prognosis of patients; (3) prognostic analysis of patients; (4) construction and validation of a predictive model for the efficacy of postoperative adjuvant chemotherapy. Comparison of count data between groups was conducted using the chi-square test. Univariate and multivariate analyses were performed using the Cox proportional hazards regression model. The Kaplan-Meier method was used to calculate survival rates and draw survival curves, and the Log-rank test was used for survival analysis. Based on the multivariate analysis result, a nomogram prediction model was constructed to predict survival benefit. Results:(1) Clinicopatho-logical characteristics of patients. The highly, moderately, and poorly differentiated tumors were observed in 16, 234, 396 cases of 646 patients aged <50 years and 279, 1 617, 811 cases of 2 707 pati-ents aged ≥50 years, respectively, showing a significant difference in degree of tumor differentiation between them ( P<0.05). For 297 patients in stage T1N1M0, cases aged <50 years and ≥50 years were 71 and 226, cases of males and females were 184 and 113, cases with negative and positive vascular invasion were 37 and 260, cases with negative and positive nerve invasion were 275 and 22, cases without and with postoperative adjuvant chemotherapy were 222 and 75, respectively. The above indicators for 678 patients in stage T2N0M0 105, 573, 533, 145, 517, 161, 526, 152, 563, 115, respectively. There were significant differences in the above indicators between the two groups ( P<0.05). (2) Influencing factors for postoperative prognosis of patients. Results of multivariate analysis showed that age ≥50 years, stage T2, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion, carcinoembryonic antigen (CEA) ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for disease-free survival (DFS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=4.600, 1.555, 1.835, 1.362, 1.451, 1.571, 2.134, 95% confidence interval as 2.806-7.541, 1.205-2.006, 1.016-3.314, 1.059-1.753, 1.057-1.993, 1.100-2.243, 1.257-3.625, P<0.05). Age ≥50 years, stage T2, the number of lymph nodes dissected <16, positive vascular invasion, CEA ≥5 μg/L, and CA19-9 ≥37 U/mL were independent risk factors for overall survival (OS) after surgery for stage Ⅰ gastric cancer ( hazard ratio=5.208, 1.597, 1.373, 1.520, 1.464, 2.356, 95% confidence interval as 3.028-8.955, 1.231-2.072, 1.060-1.777, 1.099-2.104, 1.004-2.134, 1.385-4.009, P<0.05). Postoperative adjuvant chemotherapy was an independent protective factor for both DFS and OS after surgery for stage I gastric cancer ( hazard ratio=0.361 0.297, 95% confidence interval as 0.177-0.736, 0.131-0.674, P<0.05). (3) Prognostic analysis of patients. According to the results of multi-variate analysis, among 3 353 patients, there were significant differences in 5-year DFS rate and 10-year OS rate between patients aged <50 years and ≥50 years ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in TNM stage ⅠA and ⅠB ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients in stage T1N0M0, T1N1M0, T2N0M0 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the highly, moderately, and poorly differentiated tumors ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate among patients with the number of lymph lodes dissected <16 and ≥16 ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with negative and positive vascular invasion ( P<0.05). There were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05), among patients in stage T1N0M0, T1N1M0, T2N0M0 who received no postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T1N1M0, there was no significant difference in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P>0.05).Results of stratified analysis showed that for patients aged ≥ 50 years, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients in stage T2N0M0, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). For patients with positive vascular invasion, there were significant differences in 5-year DFS rate and 10-year OS rate between patients with and without postoperative adjuvant chemotherapy ( P<0.05). (4) Construction and validation of a predictive model for the efficacy of adjuvant chemotherapy. A nomogram predictive model was constructed based on the multivariate analysis results of OS and used for calculating net benefits and distribution. Among the 3 096 patients without postoperative adjuvant chemotherapy, 1 009 cases had a predicted net benefit of >5%-10%, and 250 patients had a predicted net benefit >10%. The predicted survival analysis further verified that the predicted benefit of adjuvant chemotherapy was consistent with the prognosis of patients. Conclusions:Patients with age ≥50 years, stage T2 tumors, moderately differentiated tumor, the number of lymph nodes dissected <16, positive vascular invasion have worse survival prognosis postoperative. Postoperative adjuvant chemotherapy provides better prognosis in high-risk patients. Patients in stage T1N1M0 have lower recurrence and survival risks, of whom with 1 metastatic lymph node is more suitable for follow-up rather than postoperative adjuvant chemotherapy.