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Search Results: 1 - 10 of 402594 matches for " Olaf M. Dekkers "
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Risk factors and outcomes after unplanned extubations on the ICU: a case-control study
Robin I de Groot, Olaf M Dekkers, Ingeborg HF Herold, Evert de Jonge, M Sesmu Arbous
Critical Care , 2011, DOI: 10.1186/cc9964
Abstract: A case-control study was performed with a case to control ratio of 1:4. Incidence density sampling was applied. Seventy-four cases and 296 control patients were included.Seventy-four UEs occurred in 69 patients, comprising 2% of all mechanically ventilated patients. Multivariable regression analysis revealed that the first and second categories of the Ramsay Sedation Scale score were associated with a high risk for an UE (odds ratios (ORs) 30 and 25, respectively). Male sex, subunit of the intensive care unit (ICU), length of stay in the ICU and midazolam use at time of UE were also risk factors for an UE. Patients with an UE had lower hospital mortality than mechanically ventilated patients without UE, 10% versus 30%, respectively. Forty-seven percent (n = 35) of the patients with an UE had to be reintubated.The present study shows that the first and second categories of the Ramsay Sedation Scale were associated with a high risk for an UE. Also, male sex and use of midazolam at time of UE were identified as risk factors for an UE. However, compared with mechanically ventilated controls, no increased mortality was shown for UE patients. In UE patients without the need for subsequent reintubation, mortality was very low.Unplanned extubation (UE) is a frequent event after endotracheal intubation for respiratory support in critically ill patients and is associated with increased morbidity and mortality [1-12]. The incidence of UE among intubated patients is reported to vary from 0.3% [7] to 14% [7,13], depending on patient characteristics, the characteristics of the intensive care units (ICUs) surveyed and the duration of mechanical ventilation of the patients [14]. UEs account for approximately 10% (range, 3% to 16%) of extubations and require reintubation in 60% of the cases [4]. Furthermore, experiencing an UE is associated with prolonged duration of mechanical ventilation, ICU stay and hospital stay compared to not having experienced an UE [4,15,16]. Reported risk
Insulin Resistance and Risk of Incident Cardiovascular Events in Adults without Diabetes: Meta-Analysis
Karin B. Gast, Nathanja Tjeerdema, Theo Stijnen, Johannes W. A. Smit, Olaf M. Dekkers
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052036
Abstract: Background Glucose, insulin and Homeostasis Model Assessment Insulin Resistance (HOMA-IR) are markers of insulin resistance. The objective of this study is to compare fasting glucose, fasting insulin concentrations and HOMA-IR in strength of association with incident cardiovascular disease. Methods We searched the PubMed, MEDLINE, EMBASE, Web of Science, ScienceDirect and Cochrane Library databases from inception to March, 2011, and screened reference lists. Cohort studies or nested case-control studies that investigated the association between fasting glucose, fasting insulin or HOMA-IR and incident cardiovascular disease, were eligible. Two investigators independently performed the article selection, data extraction and risk of bias assessment. Cardiovascular endpoints were coronary heart disease (CHD), stroke or combined cardiovascular disease. We used fixed and random-effect meta-analyses to calculate the pooled relative risk for CHD, stroke and combined cardiovascular disease, comparing high to low concentrations of glucose, insulin or HOMA-IR. Study heterogeneity was calculated with the I2 statistic. To enable a comparison between cardiovascular disease risks for glucose, insulin and HOMA-IR, we calculated pooled relative risks per increase of one standard deviation. Results We included 65 studies (involving 516,325 participants) in this meta-analysis. In a random-effect meta-analysis the pooled relative risk of CHD (95% CI; I2) comparing high to low concentrations was 1.52 (1.31, 1.76; 62.4%) for glucose, 1.12 (0.92, 1.37; 41.0%) for insulin and 1.64 (1.35, 2.00; 0%) for HOMA-IR. The pooled relative risk of CHD per one standard deviation increase was 1.21 (1.13, 1.30; 64.9%) for glucose, 1.04 (0.96, 1.12; 43.0%) for insulin and 1.46 (1.26, 1.69; 0.0%) for HOMA-IR. Conclusions The relative risk of cardiovascular disease was higher for an increase of one standard deviation in HOMA-IR compared to an increase of one standard deviation in fasting glucose or fasting insulin concentration. It may be useful to add HOMA-IR to a cardiovascular risk prediction model.
High Prevalence of Metabolic Syndrome Features in Patients Previously Treated for Nonfunctioning Pituitary Macroadenoma
Sjoerd D. Joustra, Kim M. J. A. Claessen, Olaf M. Dekkers, André P. van Beek, Bruce H. R. Wolffenbuttel, Alberto M. Pereira, Nienke R. Biermasz
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0090602
Abstract: Objective Patients treated for nonfunctioning pituitary macroadenoma (NFMA) with suprasellar extension show disturbed sleep characteristics, possibly related to hypothalamic dysfunction. In addition to hypopituitarism, both structural hypothalamic damage and sleep restriction per se are associated with the metabolic syndrome. However, the prevalence of the metabolic syndrome in patients with NFMA is not well established. Our objective was to study the prevalence and risk factors for (components of) the metabolic syndrome in patients treated for NFMA. Design The metabolic syndrome (NCEP-ATP III criteria) was studied in an unselected cohort of 145 NFMA patients (aged 26–88yr, 44% female) in long-term remission after treatment, receiving adequate stable hormone replacement for any pituitary deficiencies. The results were compared to population data of 63,995 Dutch inhabitants by standardization (LifeLines cohort study). Results NFMA patients showed increased risk for reduced HDL-cholesterol (SMR 1.59, 95% CI 1.13–2.11), increased triglyceride levels (SMR 2.31, 95% CI 1.78–2.90) and the metabolic syndrome (SMR 1.60, 95% CI 1.22–2.02), but not for increased blood pressure, waist circumference or hyperglycemia. Preoperative visual field defects independently affected the risk for increased blood pressure (OR 6.5, 95% CI 1.9–22.2), and hypopituitarism was associated with a body mass index - dependent risk for increased waist circumference (OR 1.6, 95% CI 1.2–2.2) and the metabolic syndrome (OR 1.4, 95% CI 1.0–1.9). Conclusions Patients treated for NFMA are increased at risk for developing the metabolic syndrome, mainly due to decreased HDL-cholesterol and increased triglycerides. Risk factors included hypopituitarism and preoperative visual field defects. Hypothalamic dysfunction may explain the metabolic abnormalities, in addition to intrinsic imperfections of hormone replacement therapy. Additional research is required to explore the relation between derangements in circadian rhythmicity and metabolic syndrome in these patients.
Surgical Treatment for Unexplained Severe Pain of the Thyroid Gland: Report of Three Cases and Concise Review of the Literature
Jan van Schaik,Olaf M. Dekkers,Eleonora P. M. van der Kleij-Corssmit,Johannes A. Romijn,Hans Morreau,Cornelis J. H. van de Velde
Case Reports in Medicine , 2011, DOI: 10.1155/2011/349756
Abstract: Painful thyroid has a limited differential diagnosis. In rare cases, no clear cause can be found after careful clinical, biochemical, and radiological analysis. This may lead to extensive patient morbidity and frustration when symptomatic treatment proves insufficient. Hemithyroidectomy or total thyroidectomy may then be the last resort for doctor and patient. Three cases of unexplained painful thyroid which were successfully treated with hemi or total thyroidectomy are presented. In two cases extensive histological evaluation did not yield a satisfactory explanation for the extreme thyroid pain. In one case histological evaluation of the thyroid revealed Hashimoto's thyroiditis. Review of the literature does not mention surgical treatment for unexplained painful thyroid, and only 15 cases of surgical treatment for painful Hashimoto's thyroiditis are presented. Surgical therapy is a successful final option in the treatment of unexplained painful thyroid and painful Hashimoto's thyroiditis.
Survival in dialysis patients is not different between patients with diabetes as primary renal disease and patients with diabetes as a co-morbid condition
Marielle A Schroijen, Olaf M Dekkers, Diana C Grootendorst, Marlies Noordzij, Johannes A Romijn, Raymond T Krediet, Elisabeth W Boeschoten, Friedo W Dekker, the NECOSAD Study Group
BMC Nephrology , 2011, DOI: 10.1186/1471-2369-12-69
Abstract: Data were collected from the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), a multicenter, prospective cohort study in which new patients with end stage renal disease (ESRD) were monitored until transplantation or death. Patients with diabetes as primary cause of ESRD were compared with patients with diabetes as co-morbid condition and both of these patient groups were compared to patients without diabetes. Analysis was performed using Kaplan-Meier and Cox regression.Fifteen % of the patients had diabetic nephropathy as primary renal disease (N = 281); 6% had diabetes as co-morbid condition (N = 107) and 79% had no diabetes (N = 1465). During follow-up 42% of patients (N = 787) died. Compared to non-diabetic patients, mortality risk was increased for both patients with diabetes as primary renal disease HR: 1.9 (95% CI 1.6, 2.3) and for patients with diabetes as co-morbid condition HR: 1.7 (95% CI 1.3, 2.2). Mortality was not significantly higher in patients with diabetes as primary renal disease compared to patients with diabetes as co-morbid condition (HR 1.06; 95% CI 0.79, 1.43).This study in patients with ESRD showed no survival difference between patients with diabetes as primary renal disease and patients with diabetes as a co-morbid condition. Both conditions were associated with increased mortality risk compared to non-diabetic patients.Diabetes mellitus is a major contributor to the development of renal failure [1-3]. The proportion of patients with diabetes mellitus that progresses to End Stage Renal Disease (ESRD) is increasing. The increased prevalence of diabetes mellitus is estimated to account for 28% of the increased incidence of renal replacement therapy (RRT) in general [4,5]. A marked difference exists in incidence of patients with ESRD due to diabetic nephropathy between Europe and the United States. The percentage of patients entering RRT because of diabetic nephropathy is 10-15% [5] in Europe compared to 45% in the United S
AQUILA: assessment of quality in lower limb arthroplasty. An expert Delphi consensus for total knee and total hip arthroplasty
Bart G Pijls, Olaf M Dekkers, Saskia Middeldorp, Edward R Valstar, Huub JL van der Heide, Henrica MJ Van der Linden-Van der Zwaag, Rob GHH Nelissen
BMC Musculoskeletal Disorders , 2011, DOI: 10.1186/1471-2474-12-173
Abstract: A web-based Delphi was conducted consisting of two internal rounds and three external rounds in order to achieve expert consensus on items considered relevant for reporting quality, methodological quality and generalizability.The internal rounds were used to construct a master list. The first external round was completed by 44 experts, 35 of them completed the second external round and 33 of them completed the third external round. Consensus was reached on an 8-item reporting quality checklist, a 6-item methodological checklist and a 22-item generalizability checklist.Checklist for reporting quality, methodological quality and generalizability for case series and cohorts in total hip and total knee arthroplasty were successfully created through this Delphi. These checklists should improve the accuracy, completeness and quality of case series and cohorts regarding total hip and total knee arthroplasty.Observational studies (case series and cohorts) provide an important source of knowledge on total hip arthroplasty (THA) and total knee arthroplasty (TKA). In addition to personal experience, they are the most common type of evidence used by orthopaedic surgeons for clinical decision making according to a survey of the participants at the 2007 Annual Meeting of the American Orthopaedic Association [1].Nevertheless, their rank in the hierarchy of scientific evidence is lower than evidence obtained from randomised experiments, and they often suffer from lack of a control group, incomplete data collection, selection bias and confounding by indication [2]. Despite these issues, case series and cohorts are important in signalling inferior prosthesis designs, particularly those prone to aseptic loosening, which accounts for 60% of THA revisions. They are therefore a valuable addition to clinical trials and implant registries [3-6]. Further advantages are great detail, relatively low costs, short study completion time and a potentially high external validity due to the inclusi
Predicting Mortality in Patients with Diabetes Starting Dialysis
Merel van Diepen, Marielle A. Schroijen, Olaf M. Dekkers, Joris I. Rotmans, Raymond T. Krediet, Elisabeth W. Boeschoten, Friedo W. Dekker
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0089744
Abstract: Background While some prediction models have been developed for diabetic populations, prediction rules for mortality in diabetic dialysis patients are still lacking. Therefore, the objective of this study was to identify predictors for 1-year mortality in diabetic dialysis patients and use these results to develop a prediction model. Methods Data were used from the Netherlands Cooperative Study on the Adequacy of Dialysis (NECOSAD), a multicenter, prospective cohort study in which incident patients with end stage renal disease (ESRD) were monitored until transplantation or death. For the present analysis, patients with DM at baseline were included. A prediction algorithm for 1-year all-cause mortality was developed through multivariate logistic regression. Candidate predictors were selected based on literature and clinical expertise. The final model was constructed through backward selection. The model's predictive performance, measured by calibration and discrimination, was assessed and internally validated through bootstrapping. Results A total of 394 patients were available for statistical analysis; 82 (21%) patients died within one year after baseline (3 months after starting dialysis therapy). The final prediction model contained seven predictors; age, smoking, history of macrovascular complications, duration of diabetes mellitus, Karnofsky scale, serum albumin and hemoglobin level. Predictive performance was good, as shown by the c-statistic of 0.810. Internal validation showed a slightly lower, but still adequate performance. Sensitivity analyses showed stability of results. Conclusions A prediction model containing seven predictors has been identified in order to predict 1-year mortality for diabetic incident dialysis patients. Predictive performance of the model was good. Before implementing the model in clinical practice, for example for counseling patients regarding their prognosis, external validation is necessary.
Relationship between Carotid Intima Media Thickness and Helminth Infections on Flores Island, Indonesia
Aprilianto Eddy Wiria, Linda J. Wammes, Firdaus Hamid, Olaf M. Dekkers, Margaretta A. Prasetyani, Linda May, Maria M. M. Kaisar, Jaco J. Verweij, Jouke T. Tamsma, Felix Partono, Erliyani Sartono, Taniawati Supali, Maria Yazdanbakhsh, Johannes W. A. Smit
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054855
Abstract: Objective To examine the association between helminth infections and atherosclerosis. Background Chronic helminth infection, which can lead to poor nutritional status and anti-inflammatory response, might protect against the development of atherosclerosis. Methods A cross-sectional study was performed in Flores, Indonesia, an area highly endemic for soil-transmitted helminths (STH). Stool samples from 675 participants aged 18–80 years were collected and screened for Trichuris trichiura by microscopy and for Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, and Strongyloides stercoralis by qPCR. We collected data on body mass index (BMI), waist to hip ratio (WHR), blood pressure, fasting blood glucose (FBG), lipid, high sensitive C-reactive protein (hs-CRP), total immunoglobulin-E (TIgE) and Escherichia coli lipopolysaccharide stimulated cytokines (tumor necrosis factor and interleukin-10). In a subset of 301 elderly adults (≥40 years of age) carotid intima media thickness (cIMT) was measured. Results Participants with any STH infection had lower BMI (kg/m2) (mean difference ?0.66, 95%CI [?1.26, ?0.06]), WHR (?0.01, [?0.02, ?0.00]), total cholesterol (mmol/L) (?0.22, [?0.43, ?0.01]) and LDL-cholesterol (mmol/L) (?0.20, [?0.39, ?0.00]) than uninfected participants. After additional adjustment for BMI the association between helminth infection and total cholesterol (mean difference ?0.17, 95%CI [?0.37, 0.03]) as well as LDL-cholesterol (?0.15, [?0.33, 0.04]) was less pronounced. BMI, WHR, and total cholesterol were negatively associated with number species of helminth co-infections. Participants with high TIgE, an indicator of exposure to helminths, had lower FBG, TC, and HDL. The association between TIgE and TC and HDL remained significant after adjustment with BMI. No clear association was found between STH infection or TIgE and mean cIMT. Conclusions This cross-sectional study presents evidence that helminth infections were negatively associated with risk factors for cardiovascular disease, an association at least partially mediated by an effect on BMI. The significance of this finding needs to be determined.
All That Glitters Isn't Gold: A Survey on Acknowledgment of Limitations in Biomedical Studies
Gerben ter Riet, Paula Chesley, Alan G. Gross, Lara Siebeling, Patrick Muggensturm, Nadine Heller, Martin Umbehr, Daniela Vollenweider, Tsung Yu, Elie A. Akl, Lizzy Brewster, Olaf M. Dekkers, Ingrid Mühlhauser, Bernd Richter, Sonal Singh, Steven Goodman, Milo A. Puhan
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073623
Abstract: Background Acknowledgment of all serious limitations to research evidence is important for patient care and scientific progress. Formal research on how biomedical authors acknowledge limitations is scarce. Objectives To assess the extent to which limitations are acknowledged in biomedical publications explicitly, and implicitly by investigating the use of phrases that express uncertainty, so-called hedges; to assess the association between industry support and the extent of hedging. Design We analyzed reporting of limitations and use of hedges in 300 biomedical publications published in 30 high and medium -ranked journals in 2007. Hedges were assessed using linguistic software that assigned weights between 1 and 5 to each expression of uncertainty. Results Twenty-seven percent of publications (81/300) did not mention any limitations, while 73% acknowledged a median of 3 (range 1–8) limitations. Five percent mentioned a limitation in the abstract. After controlling for confounders, publications on industry-supported studies used significantly fewer hedges than publications not so supported (p = 0.028). Limitations Detection and classification of limitations was – to some extent – subjective. The weighting scheme used by the hedging detection software has subjective elements. Conclusions Reporting of limitations in biomedical publications is probably very incomplete. Transparent reporting of limitations may protect clinicians and guideline committees against overly confident beliefs and decisions and support scientific progress through better design, conduct or analysis of new studies.
Are there Hilbert-style Pure Type Systems?
M. W. Bunder,W. M. J. Dekkers
Computer Science , 2007, DOI: 10.2168/LMCS-4(1:1)2008
Abstract: For many a natural deduction style logic there is a Hilbert-style logic that is equivalent to it in that it has the same theorems (i.e. valid judgements with empty contexts). For intuitionistic logic, the axioms of the equivalent Hilbert-style logic can be propositions which are also known as the types of the combinators I, K and S. Hilbert-style versions of illative combinatory logic have formulations with axioms that are actual type statements for I, K and S. As pure type systems (PTSs)are, in a sense, equivalent to systems of illative combinatory logic, it might be thought that Hilbert-style PTSs (HPTSs) could be based in a similar way. This paper shows that some PTSs have very trivial equivalent HPTSs, with only the axioms as theorems and that for many PTSs no equivalent HPTS can exist. Most commonly used PTSs belong to these two classes. For some PTSs however, including lambda* and the PTS at the basis of the proof assistant Coq, there is a nontrivial equivalent HPTS, with axioms that are type statements for I, K and S.
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