Missing data represent a general problem in many scientific fields, especially in medical survival analysis. Dealing with censored data, interpolation method is one of important methods. However, most of the interpolation methods replace the censored data with the exact data, which will distort the real distribution of the censored data and reduce the probability of the real data falling into the interpolation data. In order to solve this problem, we in this paper propose a nonparametric method of estimating the survival function of right-censored and interval-censored data and compare its performance to SC (self-consistent) algorithm. Comparing to the average interpolation and the nearest neighbor interpolation method, the proposed method in this paper replaces the right-censored data with the interval-censored data, and greatly improves the probability of the real data falling into imputation interval. Then it bases on the empirical distribution theory to estimate the survival function of right-censored and interval-censored data. The results of numerical examples and a real breast cancer data set demonstrated that the proposed method had higher accuracy and better robustness for the different proportion of the censored data. This paper provides a good method to compare the clinical treatments performance with estimation of the survival data of the patients. This provides some help to the medical survival data analysis.
ObjectiveTo investigate the existence of persistent systemic inflammation (PSI) among patients with chronic obstructive pulmonary disease (COPD) in local areas, and identify the risk factors of PSI.MethodsA total of 150 patients with stable COPD and 70 non-smoking healthy individuals were enrolled in our study. The levels of interleukin-6 (IL-6), IL-18 and activin A in serum were detected. Pulmonary function was tested, and basic information of the candidates was acquired at the same time. All of the patients were followed-up at 6 months, 12 months and 24 months for two years. The value at the 95th percentile of the concentration of inflammation markers of non-smoking healthy samples was defined as the threshold value, also known as normal ceiling limit value. Existence of PSI was defined as the condition that two or more kinds of inflammation markers exceed the threshold at each follow-up visit. The COPD patients were categorized into three classes, in which there were respectively none, one and two or more kinds of inflammation markers with over-threshold values. Based on a 2-year followup, patients with two or more kinds of inflammation markers exceeding threshold values were classified as PSI subgroup, and patients without inflammation markers exceeding threshold values as never inflamed subgroup.ResultsThere were 22 patients (14.7%) had persistent systemic inflammation, whereas 60 patients (40.0%) did not show evidence of systemic inflammation. Single factor analysis of two subgroups showed that the patients in PSI subgroup had higher body mass index (BMI), higher smoking index, higher prior frequency of time to exacerbation, higher proportion of patients at high risk for recurrent acute exacerbation during 2-year followup, higher SGRQ total score, lower FEV1%pred and lower FEV1/FVC ratio significantly (all P<0.05). Higher BMI and higher risk of recurrent acute exacerbation were independent risk factors leading to PSI, of which the higher risk of recurrent acute exacerbation had a more important effect on PSI.ConclusionsSome COPD patients have PSI in this region, which may constitute a novel COPD phenotype (called systemic inflammatory phenotype). Higher BMI and higher risk of recurrent acute exacerbation are independent risk factors leading to PSI. Individualized treatment to prevent acute exacerbation and appropriate weight control may be a better intervention for these patients.
Objective To evaluate the safety and efficacy of simultaneous endoscopic bilateral placement of selfexpandable metal biliary stents in malignant hilar biliary obstruction． MethodFrom May 2007 to December 2010, a total of 24 patients with hilar malignancy of Bismuth type Ⅱ to Ⅳ underwent endoscopic retrograde cholangiopancreatography (ERCP) and bilateral metal stent placement. Technical success rate, functional success rate, ERCP related complications, stents’ patency time, and patient’ survival time were recorded and reviewed． Results Twentyone of 24 patients were followedup for average 39 months. Technical success rate was 100%, the average operation time was （36.2±13.9） min, the functional success rate was 95.45%. Mild cholangitis occurred in 2 cases and there was no ERCP related pancreatitis, bleeding, perforation, and death. Stents dysfunction occurred in 7 within followup period. Amonge them, plastic stents were inserted through the metallic stents in 4 cases, PTCD was required in 1 case, and conservative therapy was given in the other 2 cases. The median stent’ patency time and median patient’ survival time were 253 d (95% CI: 199.79-306.21) and 229 (95% CI : 154.53-303.47）, respectively, with no significant differences between Bismuth classification types. ConclusionEndoscopic simultaneous bilateral biliary metal stent placement is technically feasible, safe, and effective to malignant hilar obstruction.
Objective To explore a method of loading exosomes onto absorbable stents. MethodsBy building a stent-(3-aminopropyl) triethoxysilane-1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol) 5000]-exosomes connection, the exosomes were loaded onto absorbable stents to obtained the exosome-eluting absorbable stents. The surface conditions of the stents and absorption of exosomes were observed by scanning electron microscope and identified through the time-of-flight mass spectrometry; the roughness of the stents’ surfaces was observed by atomic force microscope; the appearances and sizes of the stents were observed by stereomicroscope; and the radial force was tested by tensile test machine. The absorbable stents were used as control. Results The scanning electron microscope observation showed that the exosome-eluting absorbable stents had some small irregular cracks on the surface where many exosomes could be seen. The atomic force microscopy observation showed that within the range of 5 μm2, the surface roughness of the absorbable stents was ±20 nm, while the surface roughness of the exosome-eluting absorbable stents was ±70 nm. In the results of time-of-flight mass spectrometry, both the exosome-eluting absorbable stents and exosomes had a peak at the mass charge ratio of 81 (m/z 81), while the absorbable stents did not have this peak. The peak of exosome-eluting absorbable stents at m/z 73 showed a significant decrease compared to the absorbable stents. The stereomicroscope observation showed that the sizes of exosome-eluting absorbable stents met standards and the surfaces had no cracks, burrs, or depressions. The radial force results of the exosome-eluting absorbable stents met the strength standards of the original absorbable stent. Conclusion By applying the chemical connection method, the exosomes successfully loaded onto the absorbable stents. And the sizes and radial forces of this exosome-eluting absorbable stents meet the standards of the original absorbable stents.
Objective To compare the early compl ications of carotid stenting (CAS) and carotid endarterectomy (CEA) in treatment of carotid artery stenosis. Methods Between January 2005 and December 2007, 63 patients with carotid artery stenosis were treated with CEA in 36 cases (CEA group) and with CAS in 27 cases (CAS group). There were 42 males and 21 females with an average age of 67.5 years (range, 52-79 years). The locations were the left side in 28 cases and the rightside in 35 cases. The carotid stenosis was 60%-95% (mean, 79%). The major cl inical symptoms were stroke and transient ischemic attack. The cranial CT showed old cerebral infarction in 24 cases, lacunar infarction in 22 cases, and no obvious abnormal change in 17 cases. The encephalon, heart, and local compl ications were compared between 2 groups within 7 days after operation. Results In CEA group, encephalon compl ications occurred in 3 cases (8.3%), heart compl ications in 2 cases (5.6%), and local compl ications in 5 cases (13.9%); while in CAS group, encephalon compl ications occurred in 8 cases (29.6%), heart compl ications in 1 case (3.7%), and local compl ications in 3 cases (11.1%). The encephalon compl ication ratio of CAS group was significantly higher than that of CEA group (χ2=4.855, P=0.028); and there was no significant difference in other compl ications ratios between 2 groups (P gt; 0.05). Conclusion CEA is the first choice to treat carotid artery stenosis.
ObjectiveTo study the prevention and treatment of restenosis after the stent placement in the latest progress. MethodsThere were four methods including drug-eluting stents, intracavitary illuminate, drug therapy, and mesenchymal stem cells, which prevented or treatment restenosis after stent placement. ResultsAll the four methods could reduce the postoperative restenosis rate after interventional treatment. Many experimental study of prevention and treatment of restenosis had obvious effect, but clinical curative effect was not very satisfactory, because of a series of problems such as safety, animal models, experiment method, and so on. ConclusionThe multiple factors and links caused restenosis should be considered fully, and interrupting the links or factors as far as possible could control the occurrence or development effectively.
ObjectiveTo evaluate the clinical value of in vitro fenestration and branch stent repair in the treatment of thoracoabdominal aortic aneurysm in visceral artery area assisted by 3D printing.MethodsThe clinical data of 7 patients with thoracoabdominal aortic aneurysm involving visceral artery at the Department of Vascular Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University from March 2016 to May 2019 were analyzed retrospectively. There were 5 males and 2 females with an average age of 70.2±3.9 years. Among them 4 patients had near-renal abdominal aortic aneurysm, 3 had thoracic aortic aneurysm, 4 had asymptomatic aneurysm, 2 had acute symptomatic aneurysm and 1 had threatened rupture of aneurysm. According to the preoperative CT measurement and 3D printing model, fenestration technique was used with Cook Zenith thoracic aortic stents, and branch stents were sewed on the main stents in vitro, and then the stents were modified by beam diameter technique for intracavitary treatment.ResultsAll the 7 patients completed the operation successfully, and a total of 18 branch arteries were reconstructed. The success rate of surgical instrument release was 100.0%. The average operation time was 267.0±38.5 min, the average intraoperative blood loss was 361.0±87.4 mL and the average hospital stay was 16.0±4.2 d. Immediate intraoperative angiography showed that the aneurysms were isolated, and the visceral arteries were unobstructed. Till May 2019, there was no death, stent displacement, stent occlusion, ruptured aneurysm or loss of visceral artery branches. Conclusion3D printing technology can completely copy the shape of human artery, intuitively present the anatomical structure and position of each branch of the artery, so that the fenestration technique is more accurate and the treatment scheme is more optimized.
External support stent is a potential means for restricting the deformation and reducing wall stress of the vein graft, thereby improving the long-term patency of the graft in coronary artery bypass surgery. However, there still lacks a theoretical reference for choosing the size of stent based on the diameter of graft. Taking the VEST (venous external support) stent currently used in the clinical practice as the object of study, we constructed three models of VEST stents with different diameters and coupled them respectively to a model of the great saphenous vein graft, and numerically simulated the expansion-contraction process of the vein graft under the constraint of the stents to quantitatively evaluate the influence of stent size on the radial deformation and wall stress of the vein graft. The results showed that while the stent with a small diameter had a high restrictive effect in comparison with larger stents, it led to more severe concentration of wall stress and sharper changes in radial deformation along the axis of the graft, which may have adverse influence on the graft. In order to solve the aforementioned problems, we ameliorated the design of the stent by means of changing the cross-sectional shape of the thick and thin alloy wires from circle into rectangle and square, respectively, while keeping the cross-sectional areas of alloy wires and stent topology unchanged. Further numerical simulations demonstrated that the ameliorated stent evidently reduced the degrees of wall stress concentration and abrupt changes in radial deformation, which may help improve the biomechanical environment of the graft while maintaining the restrictive role of the stent.
ObjectiveThis study was aimed to evaluate the clinical efficacy of mechanical thrombectomy using the AngioJet System for the treatment of lower extremity acute arterial embolism and thrombosis.MethodsThe clinical data of 20 patients with acute lower extremity arterial embolism and thrombosis admitted to the Department of Vascular Surgery in the People’s Hospital in Gansu Province where the author worked from September 2016 to March 2017, were retrospectively analyzed. All patients were treated with the AngioJet mechanical thrombectomy system. Clinical data of the patients were retrospectively collected. The clinical efficacy of AngioJet mechanical thrombectomy wasanalyzed.ResultsEighteen (90.0%) of the 20 patients successfully completed the mechanical thrombectomy by using the AngioJet System. The mean time for hospital stay and operation was (4.2±1.4) d and (1.3±0.4) h, respectively. The average doses of urokinase and heparin during operation were (35.80±12.30) ×104 U and (45.10±8.30) mg, respectively. Two patients received a complementary treatment of incision for removing the thrombus. Two patients received catheter-directed thrombolysis after the mechanical thrombectomy, 5 patients received bare-metal stent implantation after balloon expansion. Clinical success was in 16 cases. According to the Cooley standard, 10 patients were in excellent condition,6 in good condition, 2 in fair condition, and 2 in poor condition. There were 2 cases of distal arterial embolization,2 cases of antecardial discomfort of bradycardia, and 4 cases of bleeding at the puncture point, but no serious bleeding complications such as gastrointestinal and intracranial hemorrhage occurred. A total of 16 patients presented myoglobinuria during and after operation. All patients were followed up for 6–12 months. The results of ultrasound examination showed that the artery was patency in 15 cases. One patient died of myocardial infarction in 9 months after surgery,2 patients developed lower extremity ischemia symptoms again after surgery, and 2 patients had lower extremity ulcer caused by lower extremity ischemia symptoms. During the follow-up period, no lower limb necrosis, amputation, and death occurred in the remaining patients.ConclusionsThe AngioJet mechanical thrombectomy system is safe and effective. Combined with the use of catheter-directed thrombolysis and stent implantation, the AngioJet mechanical thrombectomy could lead to quick recovery of the perfusion of the lower extremity and improve the limb salvage rates, exhibiting excellent clinical value.
ObjectiveTo systematically review the long-term efficacy of coronary artery bypass grafting (CABG) versus drug-eluting stent implantation (DES-PCI) for patients with multivessel coronary artery disease. MethodsWe searched The Cochrane Library (Issue 2, 2015), PubMed, EMbase, CBM, CNKI, WanFang Data and VIP to collect randomized controlled trials (RCTs) about CABG versus DES-PCI for patients with coronary multivessel disease from the inception to October 2015. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies, then meta-analysis was performed by using RevMan 5.2 software. ResultsA total of seven RCTs, involving 5 723 patients were included. The results of meta-analysis showed that: compared with the DES-PCI group, the CABG group had lower 1-year incidence of target vessel revascularization (OR=0.39, 95%CI 0.31 to 0.48, P<0.000 01), 5-year mortality (OR=0.78, 95%CI 0.65 to 0.94, P=0.008), and 5-year incidence of myocardial infarction (OR=0.46, 95%CI 0.37 to 0.58, P<0.000 01). However, 1-year, 2-year and 5-year incidences of stroke in the CABG group were significantly higher than that in the DES-PCI group (all P values <0.05). ConclusionThe available evidence suggests that CABG is superior to DES-PCI for patients with multivessel coronary artery disease in long-term effects, but CABG could increase the incidence of stroke. Due to the quantity and quality of the included studies, the above conclusions still need to be verified by more high-quality RCTs.