PubMed Health⌕ Search

Biomedical subjects

Werner Vach

Publications and source records attributed to Werner Vach.

At least 19 recordsLinked to original sources
PubMed2006

[The value of myocardial perfusion scintigraphy as a "gatekeeper" for coronary angiography and revascularisation in patients with stable angina pectoris--a secondary publication].

In 507 out of a series of 972 patients referred consecutively to coronary angiography (CA) for stable angina pectoris, preceding "blinded" myocardial perfusion scintigraphy (MPS) demonstrated normal perfusion in 51%, reversible defects in 40%, and fixed defects in 9% of patients. CA showed insignificant findings in 49% and in 41% of the entire series. Of 168 revascularised patients, no more than 74% had reversible perfusion defects with MPS. On this basis it could be estimated that almost half of catheterizations and nearly one fifth of revascularisations were "superfluous".

Aged↗
PubMed2006

Attempts to predict the long-term decrease in lung function due to radiotherapy of non-small cell lung cancer.

PURPOSE: To obtain a model which can predict long-term decrease in lung function due to radiation damage from dose-volume data for patients with non-small cell lung cancer. PATIENTS AND METHODS: 27 patients were included, all long-term survivors after radical radiation therapy. For each patient a regression analysis was performed on a post-RT succession of measurements of FEV1 in order to estimate the decrease after 2 years and a standard error (SE) on this regression estimate. The modelling was based on dose-volume histograms (DVH) exported from the treatment planning system, and involved fits of threshold models, a mean lung dose model as well as more complex models based on the relative damaged volume (rdV). RESULTS: Decreases after 2 years of up to 28% in FEV1 was measured (median 10%), with significant day-to-day variation in FEV1 for the individual patient. The threshold models predicted the long-term decrease in FEV1 well when the SE was interpreted as the uncertainty of the measured decrease. The best threshold value, marginally, was 30 Gy with an R(2) of 0.46. The mean lung dose model did not perform so well. A complex model based on rdV performed better than any of the other models (R(2)=0.52). CONCLUSION: The long-term decrease in FEV1 could be predicted from a simple dose-volume model when the SE was interpreted as the uncertainty of the measured decrease.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Analysing duration of episodes of pharmacological care: an example of antidepressant use in Danish general practice.

Analysing duration of treatment episodes has become a standard task in many pharmacoepidemiological studies. However, such analyses are often carried out in a rather simplistic manner and more subtle issues are often ignored. In this paper, methods of analysing duration treatment episodes beyond simple analyses allowing investigation of the risk for certain events over time are demonstrated. In particular, the use of cumulative incidence functions, cause-specific hazard functions, hazard rate models and expected mortality in analysing duration of episodes is presented. We used these statistical techniques in analysing the early treatment history of patients who started a regular treatment with antidepressant drugs in the primary health care sector in Denmark. We have extracted some important features: The risk of discontinuing and switching treatment was very high around 10 weeks after starting treatment. After discontinuing the first treatment period, many patients soon started a second treatment period depending on the duration of the first treatment period with highest risk around 10 weeks. The mortality rate among the patients in treatment was about three times higher than the expected mortality. The risk of dying immediately after stopping treatment was about twice the expected mortality. The analysis suggests that: (1) there is a critical period for a first discontinuing, switching and restarting treatment around 10 weeks, (2) the GPs prescribing habits have more influence on the patterns than patient or drug characteristics, (3) over time Danish GPs tend to prolong the duration of first treatment period and avoid longer treatment breaks.

Adult↗
PubMed2006

Observer reproducibility and validity of systems for clinical classification of angina pectoris: comparison with radionuclide imaging and coronary angiography.

OBJECTIVE: To assess reproducibility and validity of clinical classification of angina pectoris (AP) patients. DESIGN: Fifty-six patients scheduled for coronary angiography because of stable AP were classified by two independent observers with regard to (i) type and (ii) severity of chest pain (Canadian Cardiovascular Society, CCS) and (iii) cardiac functional status (New York Heart Association, NYHA). Myocardial perfusion imaging (MPI) was performed in 55 including measurement of ejection fraction in 46, angiography was undertaken in 51. RESULTS: Observers agreed 100% on the presence (n = 45) or absence (n = 11) of angina. They agreed in 52 (93%), 48 (86%), and 42 (75%) patients with regard to type of pain, CCS grade, and NYHA class, respectively. In the remaining patients, they disagreed by one class only. The positive and negative predictive values of typical/atypical angina for perfusion abnormalities and coronary disease were 55%/82% and 53%/ 82%, respectively. CONCLUSIONS: Observer agreement was excellent for presence, type, and severity of chest pain but moderate with regard NYHA class. Clinical judgment could not predict with reasonable accuracy abnormal perfusion or coronary artery disease.

Adult↗
PubMed2006

To what degree is amelioration of angina following coronary revascularization associated with improvement in myocardial perfusion?

OBJECTIVE: To examine the association between changes in chest pain and changes in perfusion following revascularization as assessed by clinical evaluation and myocardial perfusion imaging (MPI) in patients with stable angina. DESIGN: In a prospective series of 380 patients (58.8 +/- 8.8 years) referred to angiography because of known or suspected stable angina, changes in chest discomfort and changes in perfusion after 2 years were assessed in 144 patients, who underwent revascularization, and 236, who did not. The decision to treat invasively was made without knowledge of the result of MPI. RESULTS: In revascularized patients, the presence of typical/atypical angina was reduced from 93% to 36% and the improvement was associated with improvement in perfusion. A small improvement in perfusion induced a high frequency of change from angina to no pain, whereas a further reduction caused little extra change. In non-revascularized patients the change in chest discomfort was not related to changes in perfusion, which were rarely present. CONCLUSION: Alleviation of chest discomfort 2 years after revascularization is associated with improvements in perfusion. This association appeared to be an all-or-nothing phenomenon. Non-revascularized patients also exhibited improvements in chest discomfort despite insignificant changes in perfusion.

Aged↗
PubMed2006

Prognostic value of myocardial perfusion imaging in patients with known or suspected stable angina pectoris: evaluation in a setting in which myocardial perfusion imaging did not influence the choice of treatment.

OBJECTIVE: Previous investigations on the prognostic value of myocardial perfusion imaging (MPI) were performed under circumstances in which the test result was known to the patient's physician. We wanted to examine the prognostic value of MPI in patients with known or suspected stable angina in a setting in which MPI could not influence the diagnostic and therapeutic strategy. DESIGN: A prospective series of 507 patients referred to coronary angiography for this condition were examined by MPI before angiography. Management was based on symptoms and angiographic findings, as the results of MPI were not communicated. Patients were followed for a mean of 45.3 +/- 7.7 months. RESULTS: During follow-up, 20 patients (3.9%) suffered from myocardial infarction, 19 (3.8%) died and eight (1.6%) were revascularized >1 year after MPI resulting in a combined annual event rate of 2.5%. Patients with normal MPI had a low annual event rate of 1.6% (or 1.1% with regard to myocardial infarction or death only). In contrast, event rates in patients with reversible or mixed ischaemia were 4.0% per year. MPI added independent prognostic value to standard clinical data in a multivariate Cox model. CONCLUSION: We could confirm that in patients with known or suspected stable angina, MPI is a valuable risk stratifying tool.

Adult↗
PubMed2005

Estimation of prevalence and incidence based on occurrence of health-related events.

A new method for estimating incidence and prevalence is developed, which only requires observation of occurrence of health-related events within a given time window. Occurrence data are often easy to collect but estimating incidence and prevalence of a disease from such data is non-trivial, since the true disease status is not directly observed for all at the beginning of the study period. Our method for overcoming this problem is based on an idea first presented in 'The waiting time distribution as a graphical approach to epidemiologic measures of drug utilization' (Epidemiology 1997; 8:666-670). Their fundamental idea is to analyse the waiting time from start of the window to the first event of each individual, and we formalize this by establishing a parametric likelihood which allows ordinary maximum likelihood analysis and explicit modelling of censoring. The developed method is used to analyse incidence and prevalence of hypertension in a Danish cohort of 70+-year-olds. A simulation study on the finite sample properties of the method is reported, which indicates that the method gives a quite robust and cost-effective alternative to ordinary surveys and follow-up studies for estimating incidence and prevalence.

Aged↗
PubMed2005

Potential impact of myocardial perfusion scintigraphy as gatekeeper for invasive examination and treatment in patients with stable angina pectoris: observational study without post-test referral bias.

AIMS: To evaluate the impact of using myocardial perfusion scintigraphy (MPS) as gatekeeper for coronary angiography and revascularization in stable angina pectoris. METHODS AND RESULTS: A prospective series of 507 out of 972 adult patients referred to coronary angiography for known or suspected stable angina pectoris underwent clinical examination followed immediately by MPS, the result of which was not communicated. MPS showed normal perfusion in 258/507 (51%) patients, reversible defects in 201/507 (40%), and fixed defects in 48/507 (9%). Of 168 revascularized patients, 27 (16%) had normal perfusion and 13 (8%) had fixed defects. Coronary angiography was undertaken in 476 patients of whom 252 (53%) had normal findings or insignificant stenoses. The same was the case in 361 (41%) out of the 883 of the 972 consecutive patients, who had this examination. Assuming that the true rate of normal perfusion in the entire series was correspondingly lower, 48% of catheterizations and 19% of revascularizations were superfluous. CONCLUSION: The use of MPS as gatekeeper appears to make about half of catheterizations and almost one-fifth of revascularizations redundant. Even in high-risk groups, substantial savings are possible, and the risk of overlooking patients with severe disease seems negligible.

Angina Pectoris↗
PubMed2005

The dependence of Cohen's kappa on the prevalence does not matter.

BACKGROUND AND OBJECTIVE: The dependence of Cohen's kappa on the prevalence has been a major concern in the literature. Indeed, it indicates a serious limitation with respect to comparing kappa-values among studies with varying prevalences. STUDY DESIGN AND SETTING: The basic arguments used by different authors are reviewed. RESULTS: Two types of dependence can be distinguished: a dependence on the observed marginal prevalences and a dependence on the prevalence of a latent binary variable, representing the true status. The first dependence is simply a consequence of the purpose of kappa, which is to improve the interpretation of agreement rates, and so does not constitute a real argument against kappa. The second occurs only if one can change the prevalence without changing sensitivity and specificity. Typically, in agreement studies a change in prevalence implies also a change in sensitivity and specificity, and we show that in such a framework the dependence on the prevalence becomes negligible. CONCLUSION: We should stop criticizing kappa for its dependence on the prevalence. Instead, we should focus on its dependence on the composition of the population with respect to subjects easy or difficult to agree on.

Data Interpretation, Statistical↗
PubMed2005

Use of myocardial perfusion imaging to predict the effectiveness of coronary revascularisation in patients with stable angina pectoris.

PURPOSE: Coronary revascularisation is the treatment of choice in patients with stable angina who have significant stenoses. From a pathophysiological point of view, however, mitigation of angina is to be expected only in the presence of reversible ischaemia. Therefore it was the aim of this study to examine the effect of revascularisation on stable angina in relation to the myocardial perfusion imaging (MPI) pattern prior to intervention. METHODS: Three hundred and eighty-four patients (58.0+/-8.8 years) referred for angiography underwent MPI. Prior to MPI and at 2-year follow-up, patients were classified as having typical angina, atypical angina, non-cardiac chest pain or no pain, and the severity of chest pain was graded according to the Canadian Cardiovascular Society (CCS) criteria. The patients themselves estimated their pain on a visual analogue scale. Management was based on symptoms and angiographic findings, since the results of MPI were not communicated. RESULTS: Among the 240 patients who were not revascularised, 79% had typical or atypical angina at study entrance versus 40% at follow-up. In comparison, 93% of the 144 revascularised patients had typical or atypical angina before intervention versus only 36% at follow-up. This additional advantage of invasive therapy was present only in patients with reversible defects; revascularisation had no additional effect in patients with normal perfusion or irreversible defects. Similarly, additional, significant reductions in CCS class and visual analogue score were observed exclusively in patients with reversible defects. CONCLUSION: In patients referred for coronary angiography owing to known or suspected stable angina, revascularisation was significantly more effective than medical treatment exclusively in patients with reversible ischaemia.

Angina Pectoris↗
PubMed2005

Inhibitory effects of feeding with carrots or (-)-falcarinol on development of azoxymethane-induced preneoplastic lesions in the rat colon.

The effects of intake of dietary amounts of carrot or corresponding amounts of (-)-(3R)-falcarinol from carrots on development of azoxymethane (AOM)-induced colon preneoplastic lesions were examined in male BDIX rats. Three groups of eight AOM-treated rats were fed the standard rat feed Altromin supplemented with either 10% (w/w) freeze-dried carrots with a natural content of 35 mug falcarinol/g, 10% maize starch to which was added 35 mug falcarinol/g purified from carrots, or 10% maize starch (control). After 18 weeks, the animals were euthanized and the colon was examined for tumors and aberrant crypt foci (ACF), which were classified into four size classes. Although the number of small ACF was unaffected by the feeding treatments, the numbers of lesions as a function of increasing size class decreased significantly in the rats that received one of the two experimental treatments, as compared with the control treatment. This indicates that the dietary treatments with carrot and falcarinol delayed or retarded the development of large ACF and tumors. The present study provides a new perspective on the known epidemiological associations between high intake of carrots and reduced incidence of cancers.

Alkynes↗
PubMed2005

Usefulness of the exercise electrocardiogram in diagnosing ischemic or coronary heart disease in patients with chest pain.

We compared exercise electrocardiograms with myocardial perfusion images and coronary angiograms in 186 patients who had been referred to coronary angiography for stable angina pectoris. All had normal electrocardiographic findings at rest, and none had undergone coronary revascularization. Sensitivity, specificity, and positive and negative predictive values with the exercise electrocardiogram for prediction of reversible and/or irreversible hypoperfusion were 58%, 89%, 76%, and 77% and 70%, 88%, 72%, and 87%, respectively, for prediction of reversibility only. Corresponding values for comparison with coronary angiography were 65%, 89%, 74%, and 83%, respectively. Sensitivities were considerably lower in women than in men. Exercise electrocardiographic findings were normal in 50% of women and 25% of men who had reversible perfusion defects.

Chest Pain↗
PubMed2005

Serum protein profiling by miniaturized solid-phase extraction and matrix-assisted laser desorption/ionization mass spectrometry.

Serum profiling by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) holds promise as a clinical tool for early diagnosis of cancer and other human diseases. Sample preparation is key to achieving reproducible and well-resolved signals in MALDI-MS; a prerequisite for translation of MALDI-MS based diagnostic methods to clinical applications. We have investigated a number of MALDI matrices and several miniaturized solid-phase extraction (SPE) methods for serum protein concentration and desalting with the aim of generating reproducible, high-quality protein profiles by MALDI-MS. We developed a simple protocol for serum profiling that combines a matrix mixture of 2,5-dihydroxybenzoic acid and alpha-cyano-4-hydroxycinnamic acid with miniaturized SPE and MALDI-MS. Functionalized membrane discs with hydrophobic, ion-exchange or chelating properties allowed reproducible MALDI mass spectra (m/z 1000-12,000) to be obtained from serum. In a proof-of-principle application, SPE with chelating material and MALDI-MS identified protein peaks in serum that had been previously reported for distinguishing a person diagnosed with breast cancer from a control. These preliminary results indicate that this simple SPE/MALDI-MS method for serum profiling provides a versatile and scalable platform for clinical proteomics.

Blood Proteins↗
PubMed2005

Cervicothoracic angina identified by case history and palpation findings in patients with stable angina pectoris.

OBJECTIVE: To investigate the decision-making process of an experienced chiropractor in diagnosing noncardiac musculoskeletal chest pain of cervicothoracic angina in patients with stable angina pectoris, based on patient history and clinical examination. Secondly, to examine the possibility of obtaining an objective diagnostic rule tool for the identification of cervicothoracic angina and to validate the diagnosis of this disorder. METHODS: A nonrandomized prospective trial was performed at a university hospital. A total of 516 of 972 consecutive patients referred for coronary angiography because of known or suspected angina pectoris were asked to participate in the study. Of these, 275 gave informed consent to a standardized manual examination of their spine and thorax. Diagnoses of an experienced chiropractor on cervicothoracic angina patients. Myocardial perfusion imaging and coronary angiography were used for validation. A set of candidate variables from patient history and clinical examination were tested for their role in the decision-making process. RESULTS: Eighteen percent of the patients were diagnosed with cervicothoracic angina. Of these, 80% had normal myocardial perfusion compared to 50% of cervicothoracic angina-negative patients. The main determinants of the decision-making process could be identified. CONCLUSION: An experienced chiropractor could identify a subset of patients with angina pectoris as having cervicothoracic angina. Systematic manual palpation of the spine and thorax could be used as part of the clinical examination together with basic cardiological variables to screen patients with chest pain allowing for improvements in referral patterns for specialist opinion or angiography.

Adult↗
PubMed2005

Risk grouping in stage IB squamous cell cervical carcinoma.

OBJECTIVES: To test the Gynecologic Oncology Group (GOG) prognostic criteria (based on stromal invasion, tumor size and vascular invasion) for early squamous cervical carcinoma (SCC) in an independent population and to evaluate the prognostic value of a simpler model. METHODS: We studied 221 patients who underwent radical hysterectomy and bilateral lymphadenectomy for stage IB SCC between 1987 and 1993. Adjuvant treatment consisting of radiotherapy and/or chemotherapy was given in case of large tumor size, positive lymph nodes or invasion into the parametria. Histological slides from all patients were reviewed by one pathologist. RESULTS: The GOG criteria divided the patients from our population in a small low risk group (3-year relapse-free rate (RFR) of 100%), a small high risk group (RFR of 57%) and a bigger intermediate risk group (RFR of 80-90%). These results are in good agreement with those of the original publication. A risk model based on 2 of the 3 factors used by the GOG may perform as well as the 3-factor model, especially when allowing interaction. Tumors measuring >2 cm and invading into the outer third of the cervical wall had a 5-year DFS of 56% compared to 93% for tumors measuring < or =2 cm or invading to less then the outer third of the cervical wall. CONCLUSION: The GOG criteria could be validated in this independent population. A model based on 2 of the 3 factors may perform as good.

Adult↗
PubMed2005

Parent's age and the risk of oral clefts.

BACKGROUND: Some malformations are clearly associated with older maternal age, but the effect of older age of the father is less certain. The aim of this study is to determine the degree to which maternal age and paternal age independently influence the risk of having a child with oral clefts. METHODS: Among the 1,489,014 live births in Denmark during 1973-1996, there were 1920 children with nonsyndromic cleft lip with or without cleft palate and 956 children with nonsyndromic cleft palate. We used logistic regression to assess the impact of parental age on the occurrence of cleft lip with or without cleft palate and cleft palate. Interaction between mother's and father's age was included in the analysis. RESULTS: Separate analyses of mother's and father's age showed that older age was associated with increased risk of both cleft lip with or without cleft palate and cleft palate only. In a joint analysis, both maternal and paternal ages were associated with the risk of cleft lip with or without cleft palate, but the contribution of each was dependent on the age of the other parent. In the analysis of cleft palate only, the effect of maternal age disappeared, leaving only paternal age as a risk factor. CONCLUSION: Both high maternal age and high paternal age were associated with cleft lip with or without cleft palate. Higher paternal age but not maternal age increased the risk of cleft palate only.

Adult↗