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C Ohmann

Publications and source records attributed to C Ohmann.

At least 37 records · Page 2Linked to original sources
PubMed2001

Comparison of three databases with a decision tree approach in the medical field of acute appendicitis.

Decision trees have been successfully used for years in many medical decision making applications. Transparent representation of acquired knowledge and fast algorithms made decision trees one of the most often used symbolic machine learning approaches. This paper concentrates on the problem of separating acute appendicitis, which is a special problem of acute abdominal pain from other diseases that cause acute abdominal pain by use of an decision tree approach. Early and accurate diagnosing of acute appendicitis is still a difficult and challenging problem in everyday clinical routine. An important factor in the error rate is poor discrimination between acute appendicitis and other diseases that cause acute abdominal pain. This error rate is still high, despite considerable improvements in history-taking and clinical examination, computer-aided decision-support and special investigation, such as ultrasound. We investigated three different large databases with cases of acute abdominal pain to complete this task as successful as possible. The results show that the size of the database does not necessary directly influence the success of the decision tree built on it. Surprisingly we got the best results from the decision trees built on the smallest and the biggest database, where the database with medium size (relative to the other two) was not so successful. Despite that we were able to produce decision tree classifiers that were capable of producing correct decisions on test data sets with accuracy up to 84%, sensitivity to acute appendicitis up to 90%, and specificity up to 80% on the same test set.

Abdomen, Acute↗
PubMed2001

[Preventive therapy of HNPCC--a study concept].

Due to different pattern of penetrance and heterogeneity, the role of prophylactic surgery must be individually defined for every hereditary cancer predisposition. For HNPCC (hereditary nonpolyposis colorectal cancer) subtotal colectomy at the time of colorectal cancer diagnosis is being recommended by the Cancer Genetics Studies Consortium Recent Guidelines from the DGVS (Deutsche Gesellschaft für Verdauungs- und Stoffwechselkrankheiten) state that to date no general recommendation favouring this approach can be made. The open question is: how effective is segmental resection and endoscopic surveillance in given time intervals compared with the reduction of risk by performing extended (prophylactic) surgery. Also the issue of dealing with rectal cancer as the first primary in HNPCC patients must be addressed. In order to answer these questions and after the lessons learned from BRCA mutation carriers and prophylactic mastectomies, quality of life measurement is mandatory for this study.

Colectomy↗
PubMed2001

[Coordination centers for clinical studies--structure and integration of non-university hospitals].

The Integration of non-university hospitals in clinical trials is absolutely necessary to ensure patient availability and generalisation. In our survey we observed significant problems with the conduction of clinical trials in non-university hospitals. Important aspects of these problems are caused by the lack of infrastructure and personnel as well as by rising standards for clinical conduction. The establishment of Coordination Centres for Clinical Trials (KKS) has significantly improved the ability to support clinical trials in non-university hospitals in the future.

Academies and Institutes↗
PubMed2000

Immunological surrogate parameters in a prognostic model for multi-organ failure and death.

OBJECTIVE: To assess the ability of clinical or biochemical parameters to predict outcome (survival or non-survival; severe or moderate/no complication) using multiple regression analyses. DESIGN: Prospective, descriptive cohort study with no interventions SETTING: 12 surgical intensive care units of university hospitals and large community hospitals; four medical school research laboratories in eight European countries PATIENTS: 128 surgical patients with major intra-abdominal surgery admitted for at least two days to an intensive care unit MAIN OUTCOME MEASURES: Prediction of complications or survival based on analysis of clinical (Multiple Organ Dysfunction Score, Multi-Organ-Failure Score, Acute Physiology and Chronic Health Evaluation II scores) and immunological (plasma levels of endotoxin, endotoxin neutralizing capacity, IL-6, IL-8, cell associated IL-8, Fc-receptor polymorphism, soluble CD-14) parameters, with comparison of predicted and actual outcomes. RESULTS: APACHE II, MODS score, MOF score, platelets, IL-6, IL-8, ENC, cell ass. IL-8 were significantly different between survivors and non-survivors and patients with/without severe complications by univariate analysis. By multivariate analysis only MOF, MODS score, IL-6, platelets, comorbidity predicted complications with a sensitivity of 82% and a specificity of 87%. Multivariate analysis demonstrated that only APACHE II score, plasma IL-8 and complications predicted death (sensitivity 84%; specificity 90%). CONCLUSION: Immunological surrogate parameters may predict complications and death of surgical ICU patients. The use of several parameters may add to increase sensitivity and specificity in a prognostic model.

APACHE↗
PubMed2000

Trends in peptic ulcer bleeding and surgical treatment.

An evidence-based approach is followed, with grading of evidence by study design, to evaluate surgical treatment of a bleeding peptic ulcer. In contrast to endoscopic treatment, reports of surgical treatment are rare, with only five randomized trials having been identified. Epidemiologic studies have demonstrated that the incidence of emergency surgery has not changed despite major improvements with endoscopic treatment. There are no proven alternatives to emergency operation for massive bleeding uncontrollable by endoscopic procedures. There is some debate about surgery for rebleeding, but no randomized trial has assessed whether a second endoscopic treatment alone is preferable to surgery with or without repeated endoscopic treatment. Concerning the type of operative procedure, the existing body of evidence, including two randomized studies, indicates that patients are best served by a relatively aggressive surgical approach. Today the value of these studies is limited owing to prevention of ulcer recurrence by eradication and technical improvements of local procedures (e.g., arterial ligation). Early elective surgery was tested in two randomized studies and several uncontrolled series, which demonstrated that it may be beneficial in high risk groups and harmful in others. Indications for early elective surgery should be refined taking into account updated prognostic information and more effective endoscopic treatment. Because of a new understanding of ulcer disease the role of surgery has changed markedly within the last years, no longer aiming to cure the disease but primarily to stop the hemorrhage. Evidence, however, is not derived from properly randomized controlled trials but is based on theoretic arguments and knowledge from studies not primarily dealing with operative treatment.

Emergency Treatment↗
PubMed2000

Perforated peptic ulcer: is there a difference between Eastern Europe and Germany? Copernicus Study Group and Acute Abdominal Pain Study Group.

BACKGROUND AND AIMS: Ulcer surgery and the epidemiology of peptic ulcer perforation have changed considerably in recent decades. PATIENTS/METHODS: Within two prospective studies, 170 perforated peptic ulcer patients from 12 Eastern European centres and 37 patients from 11 German centres were analysed. RESULTS: The median age of patients was 43 years in the Copernicus study and 49 years in the MEDWIS study (P=n.s.), being higher for MEDWIS female patients (73 vs 53 years, respectively; P<0.05). Female patients made up 17% (29/170) of the Copernicus study and 35% (40/170) of the MEDWIS study (P<0.05). Twenty-three per cent (40/170) of patients in the Copernicus study and 54% (20/37) in the MEDWIS study had gastric ulcer perforation (P<0.001). The proportion of definitive operations was higher in Eastern Europe (41.1%; 67/163) than it was in Germany (16.1%; 5/31) (P<0.01). German patients experienced more general complications than Eastern European patients (35 vs 12%, respectively; P<0.01) and a higher mortality [13% (5/37) vs 2% (4/170), respectively; P<0.01]. Delayed admission > or =12 h and age > or =60 years remained predictors for complications in multivariate logistic regression analysis. CONCLUSION: The proportion of both women and gastric ulcers was higher among German patients, while Eastern European patients underwent more definitive operations. German patients experienced more general complications and a higher mortality. Complications were related to high age and delayed admission.

Acute Disease↗
PubMed2000

Acute appendicitis in late adulthood: incidence, presentation, and outcome. Results of a prospective multicenter acute abdominal pain study and a review of the literature.

BACKGROUND: Acute appendicitis is the second most common cause of surgical abdominal disease in late adulthood. It is a serious condition: major errors in management are made frequently and the condition is associated with significant morbidity and mortality. Data collected within a multicenter prospective trial and a literature review were used to analyze diagnostic and therapeutic difficulties in detail. METHODS: In a multicenter intervention study (MEDWIS A 70) data from 2,280 patients with acute abdominal pain were collected prospectively. Patients with histologically proven acute appendicitis, aged 50 years and older (n=102), were compared with younger patients (n=417) to determine differences in presentation, clinical course, and outcome. The basis for the literature review was a Medline search for appendicitis in late adulthood and in the elderly, covering the years 1980-1998. In addition, studies on clinical presentation of acute appendicitis in all age groups were also reviewed and appropriate data were extracted. RESULTS: Patients aged 50 years and older with acute abdominal pain had a significantly higher incidence of surgery. Fourteen percent had acute appendicitis (27% in younger patients), with an increased complication rate (20% vs. 8%) and mortality (3% vs. 0.2%). Significantly more signs and symptoms suggestive of acute abdominal disease and peritonitis were recorded among older patients, reflecting the higher perforation rate (35% vs. 13%). Clinical presentation of appendicitis in younger patients was far more ambiguous. There were no significant differences in outcome between older and younger patients as regards perforations. Perforations are directly associated with treatment delay. Overall delay is a result of late presentation of older patients to hospital and postadmission delay. CONCLUSIONS: Appendicitis in late adulthood is characterized by a delay in treatment, high perforation rates, and unfavorable outcome parameters, all mutually correlating. Older patients with acute abdominal pain are high-risk patients, unlike their younger counterparts. They have to be clinically evaluated by experienced surgeons within a narrow time margin. The problem of late presentation and/or referral should be addressed, perhaps by education of primary care physicians and the public.

Abdomen, Acute↗
PubMed2000

Helicobacter pylori in the upper gastrointestinal tract: medical or surgical treatment of gastric lymphoma?

The treatment of primary gastric lymphoma is controversial. The role of surgery has come to be questioned with increasing knowledge about the pathogenesis of gastric lymphoma and with new therapeutic approaches such as eradication of Helicobacter pylori. We review published clinical trials of primary gastric lymphoma, including preliminary results of our own prospective multicenter trial. The results of 7 trials of H. pylori eradication and 12 prospective therapeutic trials trial are discussed. On basis of these data it is concluded that surgery with intention of R0 resection is the treatment of choice in stages EI2 and EII1 of low-grade lymphoma. In high-grade lymphomas it is still unclear whether surgery or its primary combination with radio- or chemotherapy should be preferred. The eradication of H. pylori is a promising therapeutic approach for localized low-grade mucosa-associated lymphoid tissue lymphoma. A randomized trial is needed to clarify whether medical or surgical management of localized gastric lymphoma or a combination of two is the best treatment modality.

Clinical Trials as Topic↗
PubMed2000

Macroscopic assessment of the appendix at diagnostic laparoscopy is reliable.

BACKGROUND: Healthy-looking appendixes are often removed at laparoscopy for suspected appendicitis. This practice may have adverse secondary effects. METHODS: We reviewed the literature for the years 1978 to 1998 to analyze the negative appendectomy rates, complication rates, the accuracy of laparoscopic appendix assessment, and the incidence of false negative diagnosis of appendicitis at surgical and gynecological laparoscopy. RESULTS: The respective negative appendectomy rates were 22% and 15% in studies that compared laparoscopic with open appendectomy. The appendix was left in situ in 37% of 4,281 surgical diagnostic laparoscopies. There were instances of missed appendicitis among the 3,367 gynecological diagnostic laparoscopies performed on women for lower abdominal pain, and there were 188 appendectomies in this group. Studies comparing the macroscopic appearance of the appendix at operation with microscopic findings from the excised specimen had a false negative error rate of 3%. CONCLUSIONS: Contrary to general opinion, there is no substantial evidence to support the assumption that the macroscopic diagnosis of appendicitis is unreliable. High rates of conflicting diagnoses of excision specimens suggest that endoappendicitis has little clinical significance. At present, negative appendectomy rates are considerably higher for laparoscopic appendectomy than for the open approach. The role of diagnostic laparoscopy in suspected appendicitis should be reconsidered. It may be useful in particular subgroups of patients, but it is no substitute for good clinical judgment. Furthermore, it is not always necessary to perform an incidental appendectomy.

Appendectomy↗
PubMed2000

Internet-based decision-support server for acute abdominal pain.

The paper describes conception and prototypical design of a decision-support server for acute abdominal pain. Existing formal methods to develop and exchange scores, guidelines and algorithms are used for integration. For scoring systems a work-up to separate terminological information from structure is described. The terminology is separately stored in a data dictionary and the structure in a knowledge base. This procedure enables a reuse of terminology for documentation and decision-support. The whole system covers a decision-support server written in C++ with underlying data dictionary and knowledge base, a documentation module written in Java and a CORBA middleware that establishes a connection via Internet.

Abdominal Pain↗
PubMed2000

Primary gastric B-cell lymphoma: results of a prospective multicenter study. The German-Austrian Gastrointestinal Lymphoma Study Group.

BACKGROUND & AIMS: Appropriate management of primary gastric lymphoma is controversial. This prospective, multicenter study aimed to evaluate the accuracy of endoscopic biopsy diagnosis and clinical staging procedures and assess a treatment strategy based on Helicobacter pylori status and tumor stage and grade. METHODS: Of 266 patients with primary gastric B-cell lymphoma, 236 with stages EI (n = 151) or EII (n = 85) were included in an intention-to-treat analysis. Patients with H. pylori-positive stage EI low-grade lymphoma underwent eradication therapy. Nonresponders and patients with stage EII low-grade lymphoma underwent gastric surgery. Depending on the residual tumor status and predefined risk factors, patients received either radiotherapy or no further treatment. Patients with high-grade lymphoma underwent surgery and chemotherapy at stages EI/EII, complemented by radiation in case of incomplete resection. RESULTS: Endoscopic-bioptic typing and grading and clinical staging were accurate to 73% and 70%, respectively, based on the histopathology of resected specimens. The overall 2-year survival rates for low-grade lymphoma did not differ in the risk-adjusted treatment groups, ranging from 89% to 96%. In high-grade lymphoma, patients with complete resection or microscopic tumor residuals had significantly better survival rates (88% for EI and 83% for EII) than those with macroscopic tumor residues (53%; P < 0.001). CONCLUSIONS: There is a considerable need for improvement in clinical diagnostic and staging procedures, especially with a view toward nonsurgical treatment. With the exception of eradication therapy in H. pylori-positive low-grade lymphoma of stage EI and the subgroup of locally advanced high-grade lymphoma, resection remains the treatment of choice. However, because there is an increasing trend toward stomach-conserving therapy, a randomized trial comparing cure of disease and quality of life with surgical and conservative treatment is needed.

Adult↗
PubMed2000

[Incidence of operations in Germany via telephone survey in 4 selected cities].

Considerable regional variation of surgical procedure rates has been reported for a number of countries. Influential variables that have been discussed are patient-related, physician-related and health care system-specific factors. A representative computer-assisted telephone survey was conducted in four selected regions for a study sponsored by the German Federal Ministry of Health. These regions were the townships of Aachen and Hamm in North Rhine-Westphalia and Chemnitz and Görlitz in Saxony. During the telephone survey 1897 persons were contacted and 1041 interviews completed. Multiple logistic regression showed a surgical procedure frequency which was by 40% higher in Aachen than in Hamm. During further analysis the regional localisation was replaced by region-specific structural health care information variables. During this analysis the regional frequency of medical specialists was significant at a 5% level (odds ratio: 1.07; 95% confidence interval: 1.02-1.12). This result can be interpreted as an increase in surgical procedures by 7% for each additional specialist per 10,000 persons. However, no definite conclusion can be reached based on the available data. Intensifying the presented survey-based health services research has the potential to identify regional over- or undersupply of medical services, to objectify and accompany informational, administrative or political action and thereby to support equity in access and health care in the sense of an optimized allocation of resources.

Adult↗
PubMed2000

Coverage of enterococci in community acquired secondary peritonitis: results of a randomized trial.

INTRODUCTION: The increasing number of enterococcal infections in hospitals and reports about the development of resistance of these bacteria make it necessary to review their importance as co-pathogens in secondary peritonitis. MATERIALS AND METHODS: A prospective randomized controlled trial on primary therapy of secondary peritonitis was carried out in six centers comparing cephalosporin-based antibiotic therapy to acylaminopenicillin-based therapy. RESULTS: Enterococci were only cultured in 6 of 110 cases from the abdomen and were found in only 5 cases of postoperative complications. No differences were found between penicillin-based vs. cephalosporin-based therapy. CONCLUSION: The study supports the view that these bacteria continue to play a minor role in secondary peritonitis. The point has to be emphasized, however, that the patients under study were in relatively good condition (APACHE II median 9 for cephalosporins and 10 for penicillins) and that postoperative cases of peritonitis were excluded.

Adult↗
PubMed2000

Lessons to be learned for gastroenterology from recent issues in clinical trial methodology.

Randomized trials are the preferred tool for patient-oriented research, and their main role is to enable the transfer of results from basic research to routine application. While the need for randomized trials is evident, conducting these trials is becoming increasingly difficult and complex. This article reviews actual and conflicting issues of clinical trials with respect to gastroenterology. Major problems in trial design are neglect of previous research, inadequate sample size calculations and irrelevant outcome criteria. Significant trial management problems include subversion of random allocation, and the design of systems and procedures that are inefficient, ineffective and inflexible. One of the major challenges in conducting randomized, controlled trials is obtaining informed consent because of the differing perspectives and languages of physicians and patients. Recommendations include practical guidance in obtaining informed consent, feedback of trial results to patients and support of research related to obtaining informed consent. Despite statistical guidance, several critical issues persist with respect to trial analysis. The use of confidence intervals is under-represented, the presentation of baseline data is often omitted and postsubgroup analysis is performed. Another controversial but relevant issue is the intention-to-treat analysis. Despite the formulation of standards, there is consistently poor quality of trial reporting, poor registration of unpublished trials and limited registration of ongoing trials. The authors conclude that there is a need for more randomized trials in gastroenterology. While the complexity of trial conduction has increased, so have the means of methodological and practical support. Thus, all problems can be professionally tackled, resulting in good clinical research.

Clinical Trials as Topic↗
PubMed2000

[Previous experiences with the evaluation of guidelines. Disillusionment after an enthusiastic start].

The evaluation of medical guidelines shows that the development and implementation of medical guidelines have failed to meet the high expectations raised both in Germany and internationally. Especially, the quality of German guidelines has been strongly criticized. Since then, several 'guidelines for guidelines' were published, and a variety of other measures were taken to define quality standards for the development and implementation of guidelines. It is expected that the application of these new standards will improve the quality of medical guidelines and therefore increase the chances for a more successful implementation. Only guidelines with high quality and wide acceptance, which are actually applied, will have positive effects on the process and outcome of medical care. But guidelines are only one way to improve the quality of medical care. The decision about the development and use of new guidelines should be based on the careful consideration of possible improvements and disadvantages.

Germany↗
PubMed2000

Integrating knowledge based functionality in commercial hospital information systems.

Successful integration of knowledge-based functions in the electronic patient record depends on direct and context-sensitive accessibility and availability to clinicians and must suit their workflow. In this paper we describe an exemplary integration of an existing standalone scoring system for acute abdominal pain into two different commercial hospital information systems using Java/Corba technolgy.

Abdomen, Acute↗