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.
Persistent fetal vasculature syndrome (PFVS) is a rare congenital vitreous dysplasia, which is classified as anterior, posterior and combined types according to the location of the vascular abnormalities. The clinical manifestations of PFVS are diverse, and early surgical intervention is very important. The main objective of surgical treatment is to remove the anterior and posterior traction between fibrovascular membranes and retina as well as lens, and to reconstruct clear visual axis. Surgical treatments include pupilloplasty, lensectomy with or without intraocular lens implantation and vitrectomy via limbal or scleral approach. For new technologies, the applications of ophthalmic viscosurgical device and femtosecond lasers have desirable results . In addition to focusing on improving the success rate of surgery, it is also necessary to systematically and comprehensively assess the overall preoperative condition and postoperative visual function of the patients. PFVS eyes have limited improvement in postoperative vision, which is related to the extent of lesion involvement and the occurrence of complications. Eyes with macular dysplasia and tractional retinal detachment, as well as elongated ciliary process, have a poor prognosis of vision after surgery. How to improve postoperative vision in the eye affecting the posterior segment of the eye with PFVS from the microscopic anatomical relationship between the fibrous vascular pedicle and the retina is worth further study. On the other hand, reducing surgical trauma and optimizing surgical procedures in order to improve postoperative visual acuity and reduce postoperative complications are also the key research directions of future PFVS treatments.
Objective To evaluate the value of Ureteral Stent Placement before Extracorporeal Shock Wave Lithotripsy (ESWL). Methods We searched the Cochrane Central Register of Controlled Trials (Issue 4, 2010), MEDLINE (OVID 1950 to April 2010), EMbase (1979 to April 2010), CBM (1978 to April 2010), CNKI (1979 to April 2010), and VIP (1989 to April 2010), and manually searched journals as well. All the randomized controlled trials (RCTs) of treating ureteral stone with ESWL after stent placement were included. We evaluated the risk of the bias of the included RCTs according to the Cochrane Handbook for Systematic Reviews of Interventions Version 5.0.1. The Cochrane Collaboration’s software RevMan 5.0 was used for meta-analysis. Results Three RCTs with C-level evidence involving 319 ureteral stone patients were identified. The results of meta-analyses showed that: a) Effect of treatment: The ureteral stent placement before ESWL did not take better effects in aspects of the complete clearance rate (WMD= 1.10, 95%CI 0.87 to 1.38), the quantity of lithotripsy (WMD= 0.43, 95%CI –?1.05 to 0.19), the frequency of shock wave (WMD= 0.00, 95%CI –?0.25 to 0.25), and the power of shock wave (WMD= 0.20, 95%CI –?0.05 to 0.46); and b) Postoperative complications: The ureteral stent placement were prone to cause dysuria (RR= 2.30, 95%CI 1.62 to 3.26), microscopic hematuria (RR= 2.66, 95%CI 1.97 to 3.58), gross hematuria (RR= 6.50, 95%CI 1.50 to 28.15), pyuria (RR= 1.78, 95%CI 1.44 to 2.21), positive urine culture (RR= 2.13, 95%CI 1.71 to 2.64), and suprapubic pain (RR= 3.10, 95%CI 1.59 to 6.04). Conclusions Ureteral stent placement before ESWL is inadvisable. Multi-factors which lead to bias affected the authenticity of our review, such as low-quality and small amount of RCTs. Further large-scale trials are required.
ObjectiveTo observe the efficacy of restrictive bare stent released on the distal end of the trunk of Stanford type A aortic dissection. Methods The clinical data of 22 patients with Stanford type A aortic dissection requiring aortic arch replacement and trunk surgery and selected for restrictive bare stent placement from November 2016 to February 2018 in our hospital were retrospectively analyzed. Among them, there were 19 males and 3 females, aged 34-68 (49.72±8.05) years. The bare stent was released in the descending thoracic aorta, and the stented elephant trunk was placed in the bare stent. The aortic computerized tomography angiography was reviewed before discharge and the stent position and complications were observed. ResultsOne patient failed to be implanted with bare stents due to a greater resistance and prolapse during implantation. Bare stents were successfully implanted in the remaining 21 patients. One patient died of large-area cerebral infarction after surgery and one patient suffered paraplegia. Twenty patients who survived and successfully implanted bare stents were followed up at regular intervals for 4-21 (13.00±6.14) months. No stroke or death occurred during the follow-up. The computerized tomography angiography showed good stent morphology and position, and no displacement or type Ⅲ endoleak. No stent graft-induced new entry was found. ConclusionAs an adjunct to stented elephant trunk, the use of restrictive bare stents can reduce the possibility of recurrence of a distal stent fracture, significantly expand the narrowest segment and true lumen caliber near the endoluminal graft. Aortic remodeling works well.
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.
Objective To investigate the effect of implanting uncovered self-expandable metal stent for treatment of distal malignant biliary obstruction through endoscope. Methods The effect of therapy about implanting uncovered self-expandable metal stents to 16 patients who had unsectable malignant tumors companing with obstructive jaundice through endoscope was reviewed. Results Fifteen of the studied patients were implanted uncovered self-expandable metal stents successfully (94%), for their internal drainage were patent. At the seventh and fourteenth day after implantation, liver function and B-ultrasound were rechecked. Compared to the data before operation, total bilirubin, direct bilirubin and transaminase declined respectively (P＜0.01). And the diameter of the total biliary duct became shorter (P＜0.01). Six of them returned to the normal level in three weeks. Early adverse events (in seven days) included mild acute pancreatitis (one case) and acute cholangitis (one case). Mean survival and patency of drainage were 186.93 days (54 to 426 days) and 156 days (51 to 426 days) respectively. All of them, 3 cases occured obstruction of stents (20%). Conclusion Implantation of uncovered selfexpandable metal stent through endoscope is an ideal therapy for distal malignant biliary obstruction.
Objective To investigate the therapeutic effects of endovascular covered stent on vertebral dissecting aneurysm and carotid-cavernous fistula (CCF). Methods From March 2006 to May 2007, Jostent coronary stent grafts were used to treat 4 patients with vertebral dissecting aneurysm and 3 patients with CCF. The patients of vertebral dissecting aneurysmwere male and 37-57 years old, the lesion was located on the left vertebral artery in 3 patients and on the right vertebral artery in 1 patient, with the primary symptoms of sudden headache and vomiting; CT scan demonstrated subarachnoid hemorrhage; and the medical history varied from 2 days to 10 years. The patients of CCF were male and 35-51 years old, the lesion was located on the left carotid artery in 2 patients and on the right carotid artery in 1 patient, with the primary symptoms of headache, lateral exophthalmos, eyeball distending pain, conjunctive hyperemia and impaired eyesight; all 3 patients got head injury 2 days to 1 month before the appearance of symptoms and 1 of them had a history of severe nosebleed; and the medical history ranged from 1 week to 2 months. Results For the patients with vertebral dissecting aneurysm, complete obl iteration of aneurysms was achieved, the circulations of the vertebral artery, the adjacent posterior inferior cerebellar artery and the adjacent anterior inferior cerebellar artery were smooth, no compl ications relative to operation occurred, and no recurrence of symptoms and intracranial rehaemorrhagia were observed during the follow-up period of 8 months-2 years. For the patients with CCF, the fistula were completely obl iterated, the circulation of carotid artery was smooth, the exophthalmus and conjunctiva hyperemia were improved obviously 3 days after operation, the eyesight of patient was improved at different levels over the follow-up period of 1-3 months. Conclusion Endovascular covered stent is a new and useful tool for the treatment of vertebral dissecting aneurysm and CCF .
ObjectiveTo evaluate the efficacy and safety of endovascular implantation of bare-metal stent (BMS) and endovascular implantation of drug-eluting stent (DES) in treatment of infrapopliteal arterial occlusive disease by using Meta-analysis. MethodsRandomized controlled trial about endovascular implantation of BMS and endovascular implantation of DES in treatment of infrapopliteal arterial occlusive disease were searched in domestic and international databases, literature screening in accordance with inclusion criteria and exclusion criteria was taken firstly, and then quality assessment was performed. Comparison of 1-year restenosis rate, 1-year patency rate, incidence of limb salvage, mortality, and 1-year target lesion revascularization rate after operation between BMS group and DES group were performed by using RevMan 5.2 software for Meta-analysis. ResultsSix literatures included 572 cases who suffered from infrapopliteal arterial occlusive disease were included at all, including 302 cases in DES group and 270 cases in BMS group. The results of Meta-analysis showed that, compared with BMS group, 1-year patency rate after operation in DES group was higher (OR=1.64, 95% CI:1.35-1.98, P < 0.000 1), but 1-year restenosis rate (OR=0.19, 95% CI:0.12-0.30, P < 0.000 1) and 1-year target lesion revascularization rate after operation (OR=0.09, 95% CI:0.02-0.32, P=0.000 2) were both lower. There were no significance difference between the BMS group and DES group on incidence of postoperative limb salvage (OR=1.29, 95% CI:0.58-2.86, P=0.530 0) and postoperative mortality (OR=0.98, 95% CI:0.58-1.65, P=0.940 0). ConclusionsCompared with endovascular implantation of BMS, endovascular implantation of DES can increase the 1-year patency rate and reduce 1-year restenosis rate or 1-year target lesion revascularization rate after operation for infrapopliteal arterial occlusive disease.
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.
To investigate the value of plasma placental growth factor (PlGF) in percutaneous coronary angioplasty and stent implantation. Methods From May 2006 to March 2007, 61 patients (53 males and 8 females, mean age61 years) and 28 normal controls were included. All patients present with acute chest pain and underwent coronary angiography, the lesion severity of coronary arteries was assessed by Gensini coronary scoring system. Of them, 26 patients having serious coronary lesion underwent (percutaneous transluminal coronary angioplasty, PTCA) and stent implantation. Cardiovascular events were recorded after 30 days. Plasma PlGF was determined by ELISA. Results According to the angiography, the patients could be divided into CAD group (n=45) and Non- CAD group (n=16). Plasma PlGF level in CAD group was significantly higher than that in Non-CAD group and control group [(10.70 ± 0.49) ng/L vs (4.53 ± 0.64) ng/L vs (3.64 ± 0.36) ng/L, P lt; 0.001)], and there was no significant difference between the non-CAD group and control group (P gt; 0.05). A significant positive correlation was found between Gensini coronary score and plasma PlGF level (r=0.918, P lt; 0.01). Moreover, patients with cardiovascular events had a higher PlGF level than those without cardiovascular events after PTCA and stent implantation [(13.98 ± 3.39) ng/L vs (7.25 ± 2.96) ng/L, P lt; 0.01)]. Conclusion PlGF level has diagnostic value in patients with acute chest pain. The measurement of plasma PlGF might be helpful for early diagnosis of coronary artery disease. Patients with higher plasma PlGF level may have more severe coronary lesion. PlGF may be one of predictors for cardiovascular events after PCI.