Search PubMed⌕ Search

Biomedical subjects

Lucas M Bachmann

Publications and source records attributed to Lucas M Bachmann.

At least 37 records · Page 2Linked to original sources
PubMed2004

Value of supplemental interventions to enhance the effectiveness of physical exercise during respiratory rehabilitation in COPD patients. A systematic review.

BACKGROUND: There is a controversy about the additional benefit of various supplemental interventions used in clinical practice to further enhance the effectiveness of respiratory rehabilitation in patients with Chronic obstructive pulmonary disease (COPD). The aim of this research was to assess randomised controlled trials (RCTs) testing the additional benefit of supplemental interventions during respiratory rehabilitation in COPD patients. METHODS: Systematic review with literature searches in six electronic databases, extensive hand-searching and contacting of authors. Two reviewers selected independently eligible RCTs, rated the methodological quality and extracted the data, which were analyzed considering the minimal important difference of patient-important outcomes where possible. FINDINGS: We identified 20 RCTs whereof 18 provided sufficient data for analysis. The methodological quality was low and sample sizes were too small for most trials to produce meaningful results (median total sample size = 28). Data from five trials showed that supplemental oxygen during exercise did not have clinically meaningful effects on health-related quality of life while improvements of exercise capacity may be even larger for patients exercising on room air. RCTs of adding assisted ventilation, nutritional supplements or a number of anabolically acting drugs do not provide sufficient evidence for or against the use any of these supplemental interventions. INTERPRETATION: There is insufficient evidence for most supplemental interventions during respiratory rehabilitation to estimate their additional value, partly due to methodological shortcomings of included RCTs. Current data do not suggest benefit from supplemental oxygen during exercise, although the methodological quality of included trials limits conclusions. To appropriately assess any of the various supplemental interventions used in clinical practice, pragmatic trials on respiratory rehabilitation of COPD patients need to consider methodological aspects as well as appropriate sample sizes.

Anabolic Agents↗
PubMed2004

The accuracy of the Ottawa knee rule to rule out knee fractures: a systematic review.

BACKGROUND: The Ottawa knee rule is a clinical decision aid that helps rule out fractures and avoid unnecessary radiography. PURPOSE: To summarize evidence about the accuracy of the Ottawa knee rule. DATA SOURCES: Relevant English- and non-English-language articles were identified from PreMEDLINE and MEDLINE (1966-2003), EMBASE (1980-2003), CINAHL (1982-2003), BIOSIS (1990-2003), the Cochrane Library (2002, Issue 3), the Science Citation Index database, reference lists of included studies, and experts. STUDY SELECTION: Articles were included if they reported enough information to determine the sensitivity and specificity of the Ottawa knee rule for detecting fractures confirmed either radiologically or in combination with follow-up. DATA EXTRACTION: Two reviewers independently extracted data on study samples, the ways that the Ottawa knee rule was used, and methodologic characteristics of studies. DATA SYNTHESIS: Of 11 identified studies, 6 involving 4249 adult patients were considered appropriate for pooled analysis. The pooled negative likelihood ratio was 0.05 (95% CI, 0.02 to 0.23), the pooled sensitivity was 98.5% (CI, 93.2% to 100%), and the pooled specificity was 48.6% (CI, 43.4% to 51.0%). CONCLUSION: A negative result on an Ottawa knee rule test accurately excluded knee fractures after acute knee injury. However, because the rule is calibrated toward 100% sensitivity and actual fracture prevalences are usually low, large-scale, multicentered studies are still needed to establish the cost-effectiveness of routinely implementing the rule.

Decision Support Techniques↗
PubMed2004

Minimal changes of serum creatinine predict prognosis in patients after cardiothoracic surgery: a prospective cohort study.

Acute renal failure increases risk of death after cardiac surgery. However, it is not known whether more subtle changes in renal function might have an impact on outcome. Thus, the association between small serum creatinine changes after surgery and mortality, independent of other established perioperative risk indicators, was analyzed. In a prospective cohort study in 4118 patients who underwent cardiac and thoracic aortic surgery, the effect of changes in serum creatinine within 48 h postoperatively on 30-d mortality was analyzed. Cox regression was used to correct for various established demographic preoperative risk indicators, intraoperative parameters, and postoperative complications. In the 2441 patients in whom serum creatinine decreased, early mortality was 2.6% in contrast to 8.9% in patients with increased postoperative serum creatinine values. Patients with large decreases (DeltaCrea <-0.3 mg/dl) showed a progressively increasing 30-d mortality (16 of 199 [8%]). Mortality was lowest (47 of 2195 [2.1%]) in patients in whom serum creatinine decreased to a maximum of -0.3 mg/dl; mortality increased to 6% in patients in whom serum creatinine remained unchanged or increased up to 0.5 mg/dl. Mortality (65 of 200 [32.5%]) was highest in patients in whom creatinine increased > or =0.5 mg/dl. For all groups, increases in mortality remained significant in multivariate analyses, including postoperative renal replacement therapy. After cardiac and thoracic aortic surgery, 30-d mortality was lowest in patients with a slight postoperative decrease in serum creatinine. Any even minimal increase or profound decrease of serum creatinine was associated with a substantial decrease in survival.

Adolescent↗
PubMed2004

The accuracy of various tests for bacterial vaginosis in predicting preterm birth: a systematic review.

OBJECTIVE: To determine the accuracy with which various types of tests for bacterial vaginosis predict spontaneous preterm birth in pregnant women. DATA SOURCES: Studies were identified without language restrictions through nine different databases, and manual searching of bibliographies of known primary and review articles. STUDY SELECTION AND DATA EXTRACTION: There are four different bacterial vaginosis testing methods: Gram staining tests using either Nugent's or Spiegel's criteria, and gas liquid chromatography are laboratory based, and the fourth method uses clinical (Amsel's) criteria to diagnose bacterial vaginosis. Two reviewers independently selected studies and extracted data on their characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables of the bacterial vaginosis test results with spontaneous preterm birth as the reference standard. DATA SYNTHESIS: Data on asymptomatic women and women with symptoms of threatened preterm labour were analysed separately. Data were pooled to produce summary estimates of likelihood ratios for positive (LR+) and negative (LR-) test results for the various types of tests. RESULTS: There were 18 primary articles, involving altogether 17,868 women. There was unexplained heterogeneity in the meta-analyses of the accuracy results, which requires caution in their interpretation. Meta-analyses of studies testing asymptomatic women in the second trimester showed that clinical criteria had a LR+ of 0.98 (95% confidence interval 0.59 to 1.6) and a LR- of 1.00 (0.93 to 1.1), Gram staining (Nugent's criteria) had a LR+ of 1.6 (1.4 to 1.9) and a LR- of 0.9 (0.8 to 0.9), and Gram staining (Spiegel's criteria) had a LR+ of 2.4 (1.4 to 4.9) and a LR- of 0.81 (0.64 to 1.0). Among symptomatic women, Gram staining (Spiegel's criteria) had a LR+ of 1.3 (1.0 to 1.6) and LR- of 0.9 (0.7 to 1.0). CONCLUSION: There was a lack of difference in the accuracy of the various bacterial vaginosis tests for predicting preterm birth in both asymptomatic and symptomatic women of threatened preterm labour.

Bacteriological Techniques↗
PubMed2004

Comparison of dynamic contour tonometry with goldmann applanation tonometry.

PURPOSE: The dynamic contour tonometer (DCT; Pascal tonometer) is a novel tonometer designed to measure intraocular pressure (IOP) independent of corneal properties. The purpose of this study was a comparison of the DCT with the Goldmann applanation tonometer (GAT) with respect to mean of IOP readings, the influence of ocular structural factors on IOP readings, and both intra- and interobserver variability, in a large group of healthy subjects. METHODS: In a prospective study of 228 eyes, IOP measurements by GAT and DCT were compared, and the effects of central corneal thickness (CCT), corneal curvature, axial length, and anterior chamber depth were analyzed. To evaluate intra- and interobserver variability, IOP was measured in eight eyes by four observers. RESULTS: There was a high concordance between the IOP readings obtained by DCT and GAT. However, IOP readings were consistently higher with DCT than with GAT (median difference: +1.7 mm Hg, interquartile range [25th-75th percentile] = 0.8-2.7 mm Hg). In contrast to GAT, multivariable regression analysis showed no significant effect of corneal thickness, corneal curvature, astigmatism, anterior chamber depth, and axial length on DCT readings. For repeated measurements the intraobserver variability was 0.65 mm Hg for the DCT and 1.1 mm Hg for the GAT (P = 0.008). Interobserver variability was 0.44 mm Hg for the DCT and 1.28 mm Hg for the GAT (P = 0.017). CONCLUSIONS: IOP measurements by DCT are highly concordant with IOP readings obtained from GAT but do not vary in CCT and have a lower intra- and interobserver variability. DCT seems to be an appropriate method of tonometry for routine clinical use.

Astigmatism↗
PubMed2004

Oral purified bacterial extracts in chronic bronchitis and COPD: systematic review.

BACKGROUND: Oral lyophilized extracts of bacteria species have been used since the early 1970s to improve symptoms and to prevent exacerbations in COPD patients. The value of these treatments, which are thought to be immunomodulating, is poorly understood. Our aim was to quantify the efficacy of oral bacteria extracts in patients with chronic bronchitis and COPD. DESIGN: Systematic review of randomized trials. DATA SOURCES: Electronic databases, bibliographies, and contact with authors and manufacturers. REVIEW METHODS: Randomized comparisons of oral purified bacterial (active) extracts with placebo or no treatment (control) were selected. Meta-analyses were performed using fixed and random-effects models, and the results were expressed as relative risk (RR), odds ratio (OR), number needed to treat for one to benefit (NNTB), or number needed to treat for one to be harmed (NNTH), with 95% confidence interval (CI). RESULTS: Thirteen trials (1,971 patients), most of which were of low quality, tested OM-85BV (Broncho-Vaxom; OM Pharma; Geneva, Switzerland), LW-50020 (Luivac; ALTANA Pharma; Bad Homburg, Germany), or SL-04. Two trials (731 patients) had appropriate methodologies and reported on exacerbations. The RR in favor of the oral bacterial extract (active) was 0.83 (95% CI, 0.55 to 1.25), and the NNTB was 15.4 (95% CI, 5.5 to infinity; NNTH, 27.5). Five trials (591 patients) reported on observer-assessed improvement of symptoms RR in favor of active extracts was 0.57 (95% CI, 0.49 to 0.66), and the NNTB was 4 (95% CI, 2.8 to 5.4). Two trials (n = 344), reported on patient-assessed improvement (RR, 0.44; 95% CI, 0.31 to 0.61) [NNTB, 4; 95% CI, 3.0 to 5.9]. In two trials (163 patients), the average duration of an exacerbation was shorter with the active extracts (weighted mean difference, -2.7 days; 95% CI, -3.5 to -1.8). Itching or cutaneous eruptions was reported in 3.3% of patients (four trials; 802 patients) who received active extracts compared with 1.0% of control subjects (OR, 2.94 95% CI, 1.12 to 7.69) [NNTH, 50; 95% CI, 14 to 161]. Urologic problems (two trials; 671 patients) were reported in 8% of patients who received active extracts compared with 3.0% of control subjects (OR, 2.62; 95% CI, 1.35 to 5.11) [NNTH, 22; 95% CI, 10 to 61]. CONCLUSIONS: Oral purified bacterial extracts improve symptoms in patients with chronic bronchitis and COPD. There is not enough evidence to suggest that they prevent exacerbations. Cutaneous and urologic adverse effects are common.

Administration, Oral↗
PubMed2003

Systematic reviews with individual patient data meta-analysis to evaluate diagnostic tests.

Systematic literature reviews with meta-analysis of reported data in diagnostic research studies about the accuracy of tests assist clinicians in decision-making. However, there are limitations to this approach as the analysis of such data often does not allow reviewers to explore the diagnostic information gained from combinations of tests. In recent years meta-analysis of individual patient data (IPD) has been introduced as gold standard analytic approach in systematic reviews of randomised controlled trials. Application of IPD meta-analysis in systematic reviews of diagnostic tests can allow advanced analysis to decipher the real value of testing. In particular, the additional information provided by testing can be examined in light of the information already known from history and examination. To our knowledge there are no IPD meta-analyses in diagnostic research so far. This commentary aims to highlight the benefits of IPD meta-analysis in the diagnostic domain and demonstrates how strategies for diagnostic work-up of women with postmenopausal bleeding could be improved using this approach in systematic reviews of diagnostic research on accuracy of ultrasound and hysteroscopy.

Diagnostic Tests, Routine↗
PubMed2003

A readers' guide to the interpretation of diagnostic test properties: clinical example of sepsis.

BACKGROUND: One of the most challenging practical and daily problems in intensive care medicine is the interpretation of the results from diagnostic tests. In neonatology and pediatric intensive care the early diagnosis of potentially life-threatening infections is a particularly important issue. FOCUS: A plethora of tests have been suggested to improve diagnostic decision making in the clinical setting of infection which is a clinical example used in this article. Several criteria that are critical to evidence-based appraisal of published data are often not adhered to during the study or in reporting. To enhance the critical appraisal on articles on diagnostic tests we discuss various measures of test accuracy: sensitivity, specificity, receiver operating characteristic curves, positive and negative predictive values, likelihood ratios, pretest probability, posttest probability, and diagnostic odds ratio. CONCLUSIONS: We suggest the following minimal requirements for reporting on the diagnostic accuracy of tests: a plot of the raw data, multilevel likelihood ratios, the area under the receiver operating characteristic curve, and the cutoff yielding the highest discriminative ability. For critical appraisal it is mandatory to report confidence intervals for each of these measures. Moreover, to allow comparison to the readers' patient population authors should provide data on study population characteristics, in particular on the spectrum of diseases and illness severity.

Bayes Theorem↗
PubMed2003

Electronic searching of the literature for systematic reviews of screening and diagnostic tests for preterm birth.

BACKGROUND: Published systematic reviews on prediction of preterm birth have tended to focus on a limited number of tests and their search strategies have often been relatively simple. Evaluation of all available tests in a systemic review will require a broad search strategy. AIM: To describe a case study of electronic searching for a systematic review of accuracy studies evaluating all tests for predicting preterm birth. METHODS: The search strategy, developed to capture literatures concerning all the tests en-masse consisted of formulation of an appropriate combination of search terms, pilot searches to refine the search term combination, selection of relevant databases, and citation retrieval from the refined searches for selection of potentially relevant papers. Electronic searches were carried out on general bibliographic databases (Biosis, Embase, Medline, Pascal and Scisearch), specialised databases (Database of Abstracts of Reviews of Effectiveness, Medion, National Research Register, Cochrane Controlled Trial Register and Cochrane Database of Systematic Reviews). RESULTS: A total of 30076 citations were identified. Of these 8855 (29%) citations were duplications either within a database or across databases. Of the remaining 21221 citations, 3333 were considered potentially relevant to the review after assessment by two reviewers. These citations covered 19 different tests for predicting preterm birth. CONCLUSIONS: This case study suggests that with use of a concerted effort to organise and manage the electronic searching it is feasible to undertake broad searches for systematic reviews with multiple questions.

Databases, Bibliographic↗
PubMed2003

Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review.

OBJECTIVE: To summarise the evidence on accuracy of the Ottawa ankle rules, a decision aid for excluding fractures of the ankle and mid-foot. DESIGN: Systematic review. DATA SOURCES: Electronic databases, reference lists of included studies, and experts. REVIEW METHODS: Data were extracted on the study population, the type of Ottawa ankle rules used, and methods. Sensitivities, but not specificities, were pooled using the bootstrap after inspection of the receiver operating characteristics plot. Negative likelihood ratios were pooled for several subgroups, correcting for four main methodological threats to validity. RESULTS: 32 studies met the inclusion criteria and 27 studies reporting on 15 581 patients were used for meta-analysis. The pooled negative likelihood ratios for the ankle and mid-foot were 0.08 (95% confidence interval 0.03 to 0.18) and 0.08 (0.03 to 0.20), respectively. The pooled negative likelihood ratio for both regions in children was 0.07 (0.03 to 0.18). Applying these ratios to a 15% prevalence of fracture gave a less than 1.4% probability of actual fracture in these subgroups. CONCLUSIONS: Evidence supports the Ottawa ankle rules as an accurate instrument for excluding fractures of the ankle and mid-foot. The instrument has a sensitivity of almost 100% and a modest specificity, and its use should reduce the number of unnecessary radiographs by 30-40%.

Ankle Injuries↗
PubMed2003

Assessment of clinical utility of 18F-FDG PET in patients with head and neck cancer: a probability analysis.

The purpose of this study was to calculate disease probabilities based on data of patients with head and neck cancer in the register of our institution and to perform a systematic review of the available data on the accuracy of PET in the primary assessment and follow-up of patients with head and neck cancer. The pre-test probability of head and neck cancer among patients in our institutional data registry was assessed. Then the published literature was selected and appraised according to a standard protocol of systematic reviews. Two reviewers independently selected and extracted data on study characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables and were pooled to produce summary receiver operating characteristic (ROC) curves and summary likelihood ratios for positive and negative testing. Finally post-test probabilities were calculated on the basis of the pre-test probabilities of this patient group. All patients had cytologically or histologically proven cancer. The prevalence of additional lymph node metastases on PET in staging examinations was 19.6% (11/56), and that of locoregional recurrence on restaging PET was 28.6% (12/42). In the primary assessment of patients, PET had positive and negative likelihood ratios of 3.9 (2.56-5.93) and 0.24 (0.14-0.41), respectively. Disease probabilities were therefore 49.4% for a positive test result and 5.7% for a negative test result. In the assessment of recurrence these values were 3.96 (2.8-5.6) and 0.16 (0.1-0.25), resulting in probabilities of 49.7% and 3.8%. PET evaluation for involvement of lymph nodes had positive and negative likelihood ratios of 17.26 (10.9-27.3) and 0.19 (0.13-0.27) for primary assessment and 11.0 (2.93-41.24) and 0.14 (0.01-1.88) for detection of recurrence. The probabilities were 81.2% and 4.5% for primary assessment and 73.3% and 3.4% for assessment of recurrence. It is concluded that in this clinical setting the main advantage of PET is the ability to reliably rule out the presence of disease in both staging and restaging. Further research is required to derive probabilities for individual patients from sequential testing as applied in the diagnostic work-up of patients with head and neck cancer.

Adult↗
PubMed2003

Multidimensional analysis of learning curves in laparoscopic sigmoid resection: eight-year results.

PURPOSE: The number of operations to reach a plateau phase in colorectal laparoscopic surgery is still under debate. There are few publications reporting on multidimensional assessment of the learning curve, including operation time and complication and conversion rates. The purpose of this study was to define a multidimensional learning curve for sigmoid resection performed by two surgeons with experience in laparoscopic surgery. METHODS: Between 1993 and 2001 from a total of 715 laparoscopic colorectal procedures, two surgeons performed self-educated 338 sigmoid resections. Demographic data, indications for surgery, procedure performed, operation time, frequency and kind of complications, conversion rate, and days to discharge were recorded. The moving average method was used to demonstrate the change of the operation time. The cumulative sum technique was used to chart the changes in the conversion and complication rates. RESULTS: Surgeon A performed 199 and Surgeon B 139 sigmoid resections. The operation time decreased from 225 minutes to 169 minutes after approximately 90 operations for Surgeon A and from 270 minutes to 223 minutes after 110 operations for Surgeon B. Based on a decline in intraoperative complications and conversion rate, the steady state was reached after approximately 70 to 80 interventions for both surgeons. CONCLUSIONS: The assessment of a learning curve should not be limited to measurement of a decrease in operation time but should also include the conversion and complication rates. The cumulative sum technique and moving average method as proposed in this study seem appropriate to evaluate the learning curve in this clinical domain. Our findings might be especially useful for those planning training programs in laparoscopic surgery.

Adult↗
PubMed2003

Elective cervical cerclage for prevention of preterm birth: a systematic review.

BACKGROUND: Elective cervical cerclage has been purported to prevent spontaneous preterm birth. We present a systematic review to determine the effectiveness of cervical cerclage in preventing spontaneous preterm birth before 34 weeks' gestation. METHODS: Searches were conducted in MEDLINE, EMBASE, Cochrane Library, and Science Citation Index to identify randomized trials published between 1966 and 2002. All randomized trials that evaluated the effectiveness of elective cerclage compared with no cerclage in women who were at risk of preterm birth before 34 weeks' gestation were included for analysis. Quality assessment and data extraction were performed in duplicate. RESULTS: There were seven relevant trials, comprising 2354 women. Meta-analysis was inappropriate because of large differences in the quality of the studies. However, in the largest single trial of good quality, cerclage was shown to prevent birth before 34 weeks' gestation. In this single study the reported number to be treated to prevent one additional preterm birth before 34 weeks was 24 women (95% CI: 10-61). The results of other trials were consistent with the finding of the largest trial. Data on complications were sparse and inconclusive. CONCLUSION: Our systematic review shows that elective cervical cerclage has a significant effect in preventing spontaneous preterm birth before 34 weeks' gestation. Further research should focus on identification and quantification of possible complications, and of risk factors and tests that identify high-risk women who would benefit most from cerclage.

Cerclage, Cervical↗
PubMed2003

Probability analysis for diagnosis of endometrial hyperplasia and cancer in postmenopausal bleeding: an approach for a rational diagnostic workup.

OBJECTIVE: To develop an analytical approach to estimate the probability of endometrial hyperplasia and cancer in women with postmenopausal bleeding, using a combination of patient history and tests. METHODS: A prospectively collected database of 428 postmenopausal women investigated for abnormal uterine bleeding in an outpatient rapid access clinic was used. The probability of disease was estimated using multivariable logistic regression models considering a combination of age and the use of hormone replacement therapy (HRT) and tests (ultrasound and hysteroscopy) in keeping with the actual clinical process. RESULTS: The prevalence or prior probability of endometrial cancer in the sample studied was 4.4%. Hysteroscopy alone performed better than ultrasound alone. In all patients, a negative hysteroscopy reduced the probability of cancer to 1.3%. In women less than 60 years of age who use HRT, a negative hysteroscopy further reduced this probability to 0.1%. Overall, a positive hysteroscopy raised the probability of cancer to 38.9%. However, in women over 60 years of age not using HRT, a positive hysteroscopy increased this probability to 59.4%. Combining ultrasound results with hysteroscopy did not meaningfully alter the diagnostic probability. CONCLUSION: The combination of information obtained from patient history and tests allows generation of specific disease probabilities in postmenopausal bleeding. This type of multivariable analysis puts diagnostic information gained from history and other tests into a perspective that reflects actual clinical practice.

Databases, Factual↗