Sample Size Calculation for Clinical Trials of Medical Decision Support Systems with Binary Outcome.

Currently, software products for use in medicine are actively developed. Among them, the dominant share belongs to clinical decision support systems (CDSS), which can be intelligent (based on mathematical models obtained by machine learning methods or other artificial intelligence technologies) or non-intelligent. For the state registration of CDSSs as software medical products, clinical trials are required, and the protocol of trial is developed jointly by the developer and an authorized medical organization. One of the mandatory components of the protocol is the calculation of the sample size. This article discusses the calculation of the sample size for the most common case, the binary outcome in diagnostic/screening and predictive systems. For diagnostic/screening models, cases of a non-comparative study, comparative study with testing of the superiority hypothesis, comparative study with testing of a hypothesis of non-inferiority in cross-sectional studies are considered. For predictive models, cases of randomized controlled trials of the complex intervention "prediction + prediction-dependent patient management" with testing of the hypothesis of superiority and non-inferiority are considered. It is emphasized that representativeness of the sample and other design components are no less important in clinical trials than sample size. They are even more important since systematic biases in clinical trials are primary, and even the most sophisticated statistical analysis cannot compensate for design defects. The reduction of clinical trials to external validation of models (i.e. evaluation of accuracy metrics on external data) seems completely unreasonable. It is recommended to perform clinical trials with the design adequate to the tasks, so that further clinical and economic analysis and comprehensive assessment of medical technologies are possible. The sample size calculation methods described in the article can potentially be applied to a wider range of medical devices.

[ROENTGEN-ENDOVASCULAR EMBOLIZATION OF THE PORTAL VEIN BRANCHES AS A PATIENTS CONDITIONING FOR EXTENSIVE HEPATIC RESECTION].

The results of surgical treatment of 316 patients, suffering focal hepatic diseases, in whom for preoperative preparation a portal vein embolization (PVE) was performed, were analyzed. PVE was applied in a small planned hepatic residual volume. The patients have aged from 21 to 77 yrs, (57 ± 10.6) yrs at average. During (22 ± 7) days after the procedure a hypertrophy of a planned postresectional hepatic volume by 58.6% was observed, while a hypertrophy degree have depended on the embolization volume performed: 57.3%--after embolization of branches of C(V)-C(VIII) hepatic segments, 66%--the segments C(V)-C(VIII) + C(IV). In 281 (89%) patients the extensive hepatic resection was performed, a fatal postresection hepatic insufficiency was not observed. A three-year and five-year disease-free survival have constituted 43.8 and 16.4% accordingly. Thus, a PVE constitutes a miniinvasive intervention, permitting to achieve a planned residual hepatic volume, to expand a diapazon of application of radical extensive hepatic resection in patients, suffering focal hepatic diseases while a small planned residual hepatic volume.

[Preoperative portal vein embolization: dynamics of portal pressure].

The pressure dynamics was studied in a portal vein (PV) in patients, suffering focal hepatic pathology, to whom portal vein embolization (PVE) was performed as a stage of preparation to radical hepatic resection. In 236 patients the immediate measurement of pressure in a PV was performed intraoperatively before and after PVE, in 26 - catheter for control portography and monitoring of pressure in a PV was left in its trunk for 24 h postoperatively. There was noted a pressure rising in a PV immediately after its embolization by 86.7%, positive correlation was established between PVE volume and pressure gradient in a PV before and after it. While doing monitoring during 24 h there was observed the pressure rising in a PV during 3 h after its embolization with subsequent lowering down to initial. Application of PVE as a preparation procedure for performance of extended hepatic resection, together with enhancement of residual liver minimizes sharp postresectional pressure rising in PV, what constitutes essential factor of the hepatocytes damage of residual hepatic part in immediate postoperative period.

[Results of preoperative embolization of portal vein in patients with biliary hepatic tumors].

The results of preoperative embolization of portal vein (EPV) in 90 patients, operated on for biliary hepatic tumors, were analyzed. In 47 patients Klatskin tumor was revealed, in 29--peripheral cholangiocarcinoma, in 14--tumor of a gallbladder. In all the patients a radical major hepatic resection was planned, a checking hepatic volume (CHHV) did not exceed 40% of a noninvolved parenchyma. The EPV volume have corresponded generally to the planned resection volume. After performance of EPV a pressure in a portal vein have risen by 75%, and later it have had lowered step by step during 24 h. The CHHV index have raised from (354 +/- 72) up to (462 +/- 118) cm3, or from (33 +/- 7) up to (45 +/- 11)%, permitting to perform radical hepatic resection in 79 (87.8%) patients. Thus, application of EPV in patients, suffering biliary hepatic tumors, have permitted to increase the CHHV index after radical resection, and to raise resectability of such tumors.

[The portal vein reconstruction during operations for hepatocellular carcinoma].

There was the objective to improve the results of treatment in patients, suffering hepatocellular carcinoma (HCC) with vena cava invasion by the tumor. In the main group a hepatic resection with the portal vein resection and portoplasty was performed in 21 patients, suffering HCC with vena cava invasion by the tumor of second-third degree (according to J. Shi, 2007); in a control group in 61 patients, suffering the portal vein tumoral invasion of first degree, the hepatic resection only was done. The mortality have constituted 9.5% in the main group and 8.1%--in a control one. The 5-year survival index have constituted 11.5%--in the main group and 25.3%--in a control one. The aggressive surgical tactics application for HCC with portal vein tumoral invasion permits to enhance the indices of the patients far-remote survival.

[Morphological substantiation for the surgical treatment of chronic hepatic abscess].

The results of histological investigation, conducted in 27 patients, operated on for chronic hepatic abscess, are presented. Macroscopic and microscopic characteristic of all zones of hepatic affection is adduced, the mechanisms of formation of pyogenic membrane, zones of infiltration and fibrosis in chronic hepatic abscess formation are delineated.

[Antibacterial therapy in surgical treatment of chronic hepatic abscess].

The results of surgical treatment of 58 patients for chronic hepatic abscess were presented. In patients of the main group hepatic resection was performed and in a control one--sanation and drainage of the abscess cavity. Antibacterial therapy was conducted in patients of both groups before and after operative treatment. The peculiarities and common efficacy of antibacterial therapy depending on the operative treatment kind were noted.

[Alternative endobiliary operations for choledocholithiasis and papilla of Vater stenosis].

The immediate results of endoscopic papillosphincterotomy (EPST) (n=754) and endobiliary balloon dilatation (n=120) were comparatively analyzed. Survey included patients with choledocholithiasis and papilla Vateri stenosis. The use of balloon dilatation and EPST was defined by the size and amount of gallstones. Balloon dilatation was preferable when there less then 3 concrements. "Critical" diameter of the gallstone, which permitted the use of endobiliary dilatation, was 9 mm. In cases of the papilla Vateri stenosis balloon dilatation also demonstrated better results then EPST: 93,5+/-3,6% and 79,4+/-2,8% of satisfactory results, respectively).

[Percutaneous transhepatic papillosphincterotomy and roentgen endobiliary dilatation in cholelithiasis complicated by mechanical jaundice].

A comparative analysis of treatment was made in two groups of patients with cholelithiasis complicated by mechanical jaundice who for certain causes could not be subjected to endoscopic retrograde endobiliary interventions. Percutaneous transhepatic antegrade papillosphincterotomy and endobiliary balloon dilatation extend the possibilities of rendering medical care to this category of patients. The main indications to antegrade interventions are: impossible retrograde cannulation of the major duodenal papilla, impossible endoscopic control of the position of the papillotome in the papilla zone.

[Risk assessment of the acute pancreatitis development after papilla Fateri balloon dilatation].

Data of 241 patients with acute cholecystitis, complicated with obstructive jaundice are analyzed. The risk of the acute pancreatitis development after choledocholithotomy, endoscopic papillosphincterotomy (EPST) and balloon dilatation of the papilla Fateri is assessed. Thus, choledocholithotomy and EPST, combined with the simultaneous manipulations on the terminal part of the common bile duct, are more often followed by the acute pancreatitis. Whereas the balloon dilatation of the papilla Fateri is more often followed by an asymptomatic hyperamylasuria. Demonstrated, that difficulties by papilla Fateri cannulation during EPST furthers the pancreatonecrosis development. The authors suggested a marked balloon catheter, which allows safely and effectively dilate papilla duodeni. The optimal diameter of the balloon is showed to be 1 sm wide.

Reduction of the linewidths of deep luminescence centers in 28Si reveals fingerprints of the isotope constituents.

Dramatic reductions of the linewidths of well-known deep centers in 28Si reveal "isotopic fingerprints" of the constituents. The approximately 1014 meV Cu center, thought to be either a Cu pair or an isolated Cu, is shown to contain four Cu atoms, and the approximately 780 meV Ag center is shown to contain four Ag. The approximately 944 meV ;{*}Cu center, thought to be a different configuration of a Cu pair, in fact contains three Cu and one Ag, and a new two-Cu two-Ag center is found. The approximately 735 meV center, previously assigned to Fe, actually contains Au and three Cu. This suggests a family of four-atom (Cu, Ag, Au) centers.

[Peculiarities of the venous bed vessels reconstruction while performing liver transplantation from live relative donor in children].

The rate of hepatic transplantation from live relative donor in children is increasing in all over the world and in Ukraine as well. Significant incidence of the pathology together with necessity of technically complex intervention performance causes the need for surgical technique improvement, a new methods elaboration and clinical introduction, permitting to lower the postoperative complications rate. Technical complexity constitutes the main peculiarity of transplantation operation of liver, obtained from live relative donor, in children, it is caused by the vessels small diameter, pathological changes of the recipient portal vein and lack of plastic material for reconstruction of vessels. There are proposed various plastic methods for the transplant portal inflow and venous outflow guaranteeing to achieve a success while performing left lateral hepatic section transplantation, permitting to improve the results of hepatic transplantation from live relative donor in children.

[Application of recombinant erythropoietin during preparation for hepatic transplantation operation from the living kindred donor].

First experience of application of the blood autodonorship programme, using recombinant erythropoietin (Eprex) plus preparations containing iron during their preparation for partial hepatic resection, was analyzed. Realization of this programme had permitted to escape the performance of allogenic hemotransfusion in 71.4% of donors, in whom the right or left hepatic lobe was taken out and in 100%--the left lateral section. The erythropoietin dosage regimes in different types of hepatic resections in living kindred donors were proposed.

[Epidemiologic situation of arterial hypertension on industrial enterprise].

Arterial hypertension is widely prevalent disease (38.1% in Russia) and increases death rate with coronary heart disease 3-fold, with stroke--6-fold. Multiple prospective studies proved that opportune diagnosis of arterial hypertension and other risk factors, as well as their sufficient correction considerably lower risk of occurrence and unfavorable outcomes of arterial hypertension complications. With this, organization of prophylactic programs on outpatient basis seems extremely important.

[Hepatic and the portal vein resection in the surgical treatment of hepatocellular carcinoma].

Modern problems of the portal vein resection while hepatectomy performance are enlighted. Indications for resection of the portal vein bifurcation zone are adduced, various methods of portoplasty are depicted. New methods of the portal vein passability restoration in disparity of its sutured parts diameters are proposed. The results of hepatectomy combined with portal vein resection are studied.

Optical detection and ionization of donors in specific electronic and nuclear spin States.

We resolve the remarkably sharp bound exciton transitions of highly enriched 28Si using a single-frequency laser and photoluminescence excitation spectroscopy, as well as photocurrent spectroscopy. Well-resolved doublets in the spectrum of the 31P donor reflect the hyperfine coupling of the electronic and nuclear donor spins. The optical detection of the nuclear spin state, and selective pumping and ionization of donors in specific electronic and nuclear spin states, suggests a number of new possibilities which could be useful for the realization of silicon-based quantum computers.

[Peculiarities of splanchnic hemodynamics after performance of partial portosystemic shunting].

Complex hemodynamical investigations were conducted in 1985-2004 yrs in 60 patients with hepatic diseases before the operation, in 6-8 and 12-24 months after performance of portosystemic shunting operation (in 26 patients was formed H-like mesentericocaval anastomosis, in 10--central splenorenal anastomosis, in 14--splenorenal anastomosis side-to-side, in 10--H-like splenorenal anastomosis). Performance of shunting operation had promoted the lowering of volumetric speed of blood flow and pressure in portal vein, her diameter reduction, the general hepatic blood flow lowering. The lowering of blood flow in the portal vein system after the shunting have caused enhancement of arterial hepatic blood flow.