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Biomedical subjects

Peter Matzen

Publications and source records attributed to Peter Matzen.

12 recordsLinked to original sources
PubMed2005

[Measures for the performance of diagnostic tests].

Systematic reviews have revealed that the methodological quality of studies on diagnostic accuracy is mediocre. In addition, clinicians may experience difficulties in interpreting and using measures describing the accuracy of a test. Using the Ottawa Ankle Rule as an example, we review the measures commonly used to describe the accuracy of diagnostic tests. The performance of tests is often given in terms of sensitivity and specificity. However, these measures have no relevance to clinicians unless they can be converted into predictive values. We describe how to calculate the predictive values and how they can be determined using likelihood ratios and Fagan's nomogram. The reader is introduced to the critical appraisal of results based on studies of the accuracy of tests. We describe how both the clinical spectrum and the methodological quality can influence estimates of diagnostic accuracy and stress the inevitable uncertainty involved in extrapolating results from the literature to clinical practice. Methods of calculating the confidence intervals for estimates of accuracy are presented.

Ankle Injuries↗
PubMed2005

Increased risk of intestinal cancer in Crohn's disease: a meta-analysis of population-based cohort studies.

OBJECTIVES: The risk of intestinal malignancy in Crohn's disease (CD) remains uncertain since risk estimates vary worldwide. The global CD population is growing and there is a demand for better knowledge of prognosis of this disease. Hence, the aim of the present study was to conduct a meta-analysis of population-based data on intestinal cancer risk in CD. METHODS: The MEDLINE search engine and abstracts from international conferences were searched for the relevant literature by use of explicit search criteria. All papers fulfilling the strict inclusion criteria were scrutinized for data on population size, time of follow-up, and observed to expected cancer rates. STATA meta-analysis software was used to perform overall pooled risk estimates (standardized incidence ratio (SIR), observed/expected) and meta-regression analyses of the influence of specific variables on SIR. RESULTS: Six papers fulfilled the inclusion criteria and reported SIRs of colorectal cancer (CRC) in CD varying from 0.9 to 2.2. The pooled SIR for CRC was significantly increased (SIR, 1.9; 95% CI 1.4-2.5), as was the risk for colon cancer separately (SIR, 2.5; 95% CI 1.7-3.5). Regarding small bowel cancer, five studies reported SIRs ranging from 3.4 to 66.7, and the overall pooled estimate was 27.1 (95% CI 14.9-49.2). CONCLUSIONS: The present meta-analysis of intestinal cancer risk in CD, based on population-based studies only, revealed an overall increased risk of both CRC and small bowel cancer among patients with CD. However, some of the available data were several decades old, and future studies taking new treatment strategies into account are required.

Cohort Studies↗
PubMed2004

Complications of ERCP: a prospective study.

BACKGROUND: Studies of ERCP-related morbidity seldom include a sufficient patient follow-up. The aim of this study was to characterize and to evaluate the frequency of complications, cardiopulmonary untoward events in particular. METHODS: All patients undergoing ERCP during a 2-year period were included in this prospective study. Complications were assessed at the time of ERCP and by postal/telephone contact at 30-days after the procedure. RESULTS: A total of 1177 ERCPs were included in the analysis, of which 56.2% were therapeutic. The 30-day complication rate was 15.9%; the procedure-related mortality rate was 1.0%. Post-ERCP pancreatitis occurred in 3.8% of patients (3 deaths). Hemorrhage or perforation occurred with 0.9% and 1.1%, respectively, of the procedures (3 deaths). One perforation that resulted in the death of the patient occurred after placement of an endoprosthesis. Cholangitis occurred in relation to 5% of the ERCP procedures (3 deaths). Cardiorespiratory complications occurred in 2.3% (2 deaths). Dilated bile duct ( p = 0.0001), placement of stent ( p = 0.001), and use of more than 40 mg of hyoscine-N-butyl bromide ( p < 0.05) were risk factors for complications by multivariate analysis. Risk of pancreatitis was increased with age under 40 years ( p = 0.0078), placement of stent ( p = 0.031), and a dilated bile duct ( p = 0.036). CONCLUSIONS: This prospective study confirms that the complication rate of ERCP including therapeutic procedures is high. Cardiopulmonary complications were not as common as expected, despite being the special focus of the study.

Adolescent↗
PubMed2003

[How evidence-based is medicine? A systematic literature review].

INTRODUCTION: In the early 1990es, it was supposed that only 10-15 per cent of medical interventions were based on results from randomised controlled studies. A systematic review of available empirical studies on the topic was performed in order to elucidate to what extent interventions in different medical specialities are evidence-based. METHODS: Literature search in MEDLINE for the period 1995-2002 retrieved 15 published studies, which investigated to what extent interventions in individual patients were based on randomised controlled studies. The retrieved papers were read critically in order to extract data concerning the patients, their clinical problems, and the interventions performed. Finally, the classification of the clinical scientific methods, which was the evidence-base of the interventions, were extracted. RESULTS: In general internal medicine over 50 per cent of the interventions seems warranted by randomised controlled studies, whereas the figures are somewhat lower for general practice, surgery, and dermatology. A small study shows that psychiatry may candidate for the top score with 65 per cent of the interventions based on randomised controlled studies. However, more studies are requested to confirm this finding. DISCUSSION: It is suggested to perform regular studies of the evidence-base for clinical interventions in different specialities, preferably with assistance from colleagues from other specialities. There should be sufficient access to literature databases and databases of "digested" evidence, which was not always the case in the reviewed studies. It is important that the indication for an intervention has been evaluated in randomised controlled studies, which compared a possible intervention to observation without treatment or treatment with placebo--a mere comparison in randomised controlled studies of two active interventions may not be sufficient evidence. Authors are encouraged to agree on a comparable classification scale for grading the evidence in publications. It is concluded that there is a need for this kind of regular audit in order to safeguard that patients are offered interventions based on the best evidence.

Clinical Medicine↗
PubMed2002

[Treatment of chronic anal fissure with topically applied nitroglycerin ointment. A systematic review of evidence-based results].

This study explores the evidence-based background for treating chronic anal fissure with topically applied nitroglycerin (NTG): in part the general effect of NTG and in part how its effect compares to that of surgery, which has been claimed to have long-term complications like incontinence for flatus and faeces. Ten randomised clinical trials published up to July 2001 were retrieved. In five of six studies, NTG had an effect on healing that was better than that of placebo or lignocaine. Headache is a common side effect of the treatment. Lateral internal sphincterotomy, the operation of choice for chronic anal fissure, and topical NTG were compared in four trials. Surgery had a better healing rate, but more late complications. The results suggest that in 31-65% of patients an operation could be avoided with NTG therapy. Topically applied 0.2% nitroglycerin three times a day for four weeks is therefore the primary choice in the treatment of anal fissures. But the possibility still remains that the observed effect of NTG may be the outcome of publication bias.

Administration, Topical↗
PubMed2002

Preoperative endoscopic stent placement before pancreaticoduodenectomy: a meta-analysis of the effect on morbidity and mortality.

BACKGROUND: Pancreaticoduodenectomy is the only potentially curative treatment for peripapillary pancreatic tumors. However, postoperative morbidity and mortality are high, and different approaches have been tried to improve results, such as preoperative biliary drainage in patients with jaundice. This meta-analysis investigated the effect on postoperative outcome of preoperative biliary drainage by endoscopic biliary stent placement in patients who are jaundiced and who have peripapillary pancreatic tumors. METHODS: A Medline search for the period 1985 to 2001 was performed. Eight retrospective studies and 2 prospective randomized controlled trials were included. Selection criteria for the primary analysis were as follows: patients with peripapillary pancreatic cancer, endoscopic stent placement versus no stent, radical surgery, and assessment of postoperative morbidity and mortality. A secondary analysis included both radical and palliative surgery. RESULTS: In the primary analysis, 337 patients underwent preoperative endoscopic biliary stent placement, and 412 patients had no endoscopic biliary stent placement (controls). The overall odds ratio for postoperative complications (stent vs. no stent) is estimated as 0.79: 95% CI [0.36, 1.73] and the estimated odds ratio for postoperative mortality is 0.81: 95% CI [0.33, 1.99]. In the secondary analysis, 1008 patients underwent preoperative EBS versus 720 control patients. The odds ratio for postoperative complications in this analysis was 0.93: 95% CI [0.65, 1.33] and for postoperative mortality is 1.12: 95% CI [0.62, 2.01]. CONCLUSION: No evidence was found of either a positive or adverse effect of preoperative endoscopic biliary stent placement on the outcome of surgery in patients with pancreatic cancer.

Confidence Intervals↗