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PubMed2005

Handling missing data in patient-level cost-effectiveness analysis alongside randomised clinical trials.

BACKGROUND: Missing data are potentially an extensive problem in cost-effectiveness analyses conducted alongside randomised clinical trials, where prospective collection of both resource use and health outcome information is required. There are several possible reasons for the presence of incomplete records, and the validity of the analysis in the presence of data with missing values is dependent upon the mechanism generating the missing data phenomenon. In the past, the most commonly used methods for analysing datasets with incomplete observations were relatively ad hoc (e.g. case deletion, mean imputation) and suffered from potential limitations. Recently, several alternative and more sophisticated approaches (e.g. multiple imputation) have been proposed that attempt to correct the flaws of the simple imputation methods. OBJECTIVES: The objectives are to provide a concise and accessible description of the quantitative methods most commonly used in trial-based cost-effectiveness analysis for handling missing data, and also to demonstrate the potential impact of these alternative approaches on the cost-effectiveness results reported in two case studies. METHODS: Data from two recently conducted, trial-based economic evaluations are used to explore the sensitivity of the study results to the technique used to deal with incomplete observations. A statistical framework for representing the uncertainty in the alternative methods is outlined using an approach based on net benefits and cost-effectiveness acceptability curves. RESULTS: The case studies demonstrate the potential importance of the approach used to handle missing data. Although the analytical strategy did not appear to alter the results of one of the studies, the other case study showed that that the results of the cost-effectiveness analysis were sensitive to both the decision to impute and also the imputation strategy adopted. CONCLUSIONS: Analysts should be more explicit in reporting the analytical strategies applied in the presence of missing data. The use of a multiple imputation approach is recommended in the majority of cases, so as to adequately reflect the uncertainty in the study results due to the presence of missing data.

Bias↗
PubMed1998

Prognostic value of congestive heart failure history in patients undergoing percutaneous coronary interventions.

OBJECTIVES: We sought to determine the prognostic significance of a history of congestive heart failure above that provided by baseline ejection fraction in patients undergoing percutaneous coronary interventions. BACKGROUND: Left ventricular function is a known predictor of survival in patients with coronary artery disease, as is a history of congestive heart failure. The contribution of heart failure history independent of left ventricular function is unknown. METHODS: Data were pooled from four interventional trials and the Duke University database. The combined dataset included 5,260 patients undergoing percutaneous interventions, 334 with and 4,926 without a history of heart failure. Patients were defined by the treating physician as having a clinical history of heart failure at the time of enrollment. RESULTS: The 30-day and 6-month mortality were higher in patients with a clinical history of congestive heart failure than in those without such a history (2% vs. <1%, p=0.002 at 30 days, 5% vs. 1%, p=0.001 at 6 months). Heart failure history did not influence the incidence of myocardial infarction, use of angioplasty or the use of bypass surgery during follow-up. Multivariable analysis revealed that heart failure history added significantly to ejection fraction in predicting intermediate-term (6-month) mortality (p=0.01). Stepwise logistic regression also revealed heart failure history to be an independent predictor of 6-month mortality (odds risk 1.9, 95% confidence interval 1.1 to 3.5). CONCLUSIONS: A clinical history of congestive heart failure is associated with increased early and intermediate-term mortality in patients undergoing percutaneous revascularization. Congestive heart failure history appears to provide prognostic information independent of that available from a patient's left ventricular function. These findings suggest that patients with a clinical history of congestive heart failure who undergo a percutaneous intervention should be closely monitored, especially those with the lowest ejection fractions.

Aged↗
PubMed2006

Safety and tolerability of tegaserod in patients with chronic constipation: pooled data from two phase III studies.

BACKGROUND & AIMS: Studies show that tegaserod effectively relieves the symptoms of chronic constipation/idiopathic constipation (CC). This pooled analysis assessed the safety and tolerability of tegaserod in a large dataset of CC patients. METHODS: Adverse event (AE) data were pooled from 2 double-blind, placebo-controlled phase III trials of 12 weeks' duration. Post hoc analysis was conducted for the most frequent AEs (incidence, >or=3%). RESULTS: Eight hundred eighty-one, 861, and 861 patients received tegaserod 6 mg twice a day, 2 mg twice a day, or placebo, respectively. Most AEs were mild/moderately severe. AE incidence was similar for the tegaserod 6 mg and 2 mg twice a day (57.1% and 56.3%, respectively) and placebo groups (59.6%) and most frequent in the gastrointestinal system (tegaserod 6 mg twice a day, 25.8%; 2 mg twice a day, 22.5%; placebo, 24.6%). Headache, the most common AE, was slightly more frequent in the placebo group (tegaserod 6 mg twice a day, 11.0%; 2 mg twice a day, 10.1%; placebo, 13.2%). Diarrhea (generally transient and resolved with continued treatment) was the only AE with a statistically significant difference between groups (tegaserod 6 mg twice a day 6.6% vs placebo 3.0%, P=.0005). Serious AE incidence (1.4% overall) was comparable across treatment groups, although abdominal surgery was less common in the combined tegaserod (0.5%) than the placebo group (1.0%). Discontinuation as a result of AEs was slightly higher in tegaserod 6 mg twice a day patients (5.7%; 2 mg twice a day, 3.3%; placebo, 3.7%), mainly because of diarrhea. Laboratory and electrocardiogram parameters were comparable across groups. CONCLUSIONS: Tegaserod is well tolerated by patients with CC during 12 weeks of treatment.

Administration, Oral↗
PubMed2004

Construction, training and clinical validation of an interpretation system for genotypic HIV-1 drug resistance based on fuzzy rules revised by virological outcomes.

OBJECTIVES: To evaluate whether fuzzy operators can be usefully applied to the interpretation of genotypic HIV-1 drug resistance by experts, and to improve the prediction of salvage therapy outcome by adapting interpretation rules of genotypic resistance on the basis of their association with virological response data. METHODS: We used a clinical dataset of 231 patients failing highly active antiretroviral therapy (HAART) and starting salvage therapy with baseline resistance genotyping and virological outcomes after 3 and 6 months. A set of rules predicting genotypic resistance was initially derived from an expert (ADL). Rules were implemented using a fuzzy logic approach and the virological outcomes dataset used for the training phase. The resulting algorithm was validated using a separate set of 184 selected patients by correlating the resulting predicted activity with observed virological response at 3 months. For comparison, the expert systems from the drug resistance group of the Agence Nationale de Recherches sur le SIDA (ANRS-AC11) and the algorithm from the Stanford's HIV drug resistance database (Stanford HIVdb) were evaluated on the same set. RESULTS: The starting algorithm had a correlation with virological outcomes of R2=0.06 (P=0.0001). After the training phase the correlation with virological outcomes increased to R2=0.19 (P<0.000001). In the validation set of patients, the activity of the salvage regimen predicted by the fuzzy algorithm was the only variable independently predictive of the 3-month viral load change even after adjusting by the activity predicted by the two expert systems and baseline viral load (for each 10% salvage regimen's activity increase, mean HIV RNA change from baseline: -0.27 log10 copies/ml; 95% CI -0.39, -0.15). CONCLUSION: Using fuzzy operators in a virological outcomes training database to implement a rules-based algorithm for genotypic resistance interpretation, significant improvements of outcomes prediction were obtained. The resulting algorithm showed an independent predictive capability of virological outcomes over that of two rules-based interpretation algorithms made by experts. Although the system was trained and validated on a limited number of cases, the approach deserves further evaluation.

Adolescent↗
PubMed2003

Laryngeal cancer in women: tobacco, alcohol, nutritional, and hormonal factors.

Laryngeal cancer is the neoplasm with the largest male to female sex ratio in most populations. Thus, inadequate data are available on women. We analyzed several risk factors in the combined dataset from two case-control studies conducted between 1986 and 2000 in northern Italy and Switzerland. Cases were 68 women under age 79 years, with incident, histologically confirmed cancer of the larynx. Controls were 340 women, admitted to the same network of hospitals as cases, for acute, nonmalignant conditions, unrelated to tobacco and alcohol consumption. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were estimated by logistic regression models, conditioned by age, study center and year of interview, and including terms for education, body mass index, tobacco, alcohol drinking, and nonalcohol energy intake. Laryngeal cancer was strongly associated with cigarette smoking (OR = 435.7, 95% CI: 38.2-4964.4 for smokers of >/=25 cigarettes/day) and alcohol drinking (OR = 4.3, 95% CI: 0.8-24.1 for >/=5 drinks/day). An inverse relation was found for vegetables (OR = 0.3, 95% CI: 0.1-0.9 for the highest level of consumption), fruit (OR = 0.5, 95% CI: 0.2-1.3), and olive oil (OR = 0.3, 95% CI: 0.1-0.9). Reproductive and hormonal factors were not consistently associated to laryngeal cancer risk. This investigation, based on a uniquely large number of laryngeal cancers in women, provides definite evidence that cigarette smoking is the prominent risk factor for laryngeal cancer in women, accounting for 78% of cases in this population. Alcohol and selected dietary aspects account for approximately 30% of cases, whereas menstrual and hormonal factors do not appear to have a consistent role in laryngeal carcinogenesis.

Aged↗
PubMed2003

Intravenous immunoglobulins for multiple sclerosis.

BACKGROUND: From animal experiments, there is evidence to suggest that intravenous immunoglobulins can reverse some of the disease process of central nervous system demyelination. Subsequently, clinical trials of intravenous immunoglobulins have been conducted in people with multiple sclerosis (MS). OBJECTIVES: To identify and summarise the evidence that intravenous immunoglobulins are safe and beneficial for people with MS. SEARCH STRATEGY: We searched the Cochrane Multiple Sclerosis Group trials Register( January 2003) The Cochrane Central Register of Controlled Trials (The Cochrane Library issue 4, 2002), MEDLINE (January 1966 to April 2001), EMBASE (January 1988 to April 2001) and reference lists of articles. We also contacted relevant pharmaceutical companies and authors of identified trials. SELECTION CRITERIA: Randomised controlled trials of intravenous immunoglobulins for the secondary prevention of relapses and disease progression in MS. DATA COLLECTION AND ANALYSIS: 913 titles and abstracts were obtained from the literature search, and we eventually identified 10 clinical trials. All reviewers agreed on the final dataset for entry into RevMan 4.1, and summarised the results. Study authors were contacted for additional information but no response was obtained. MAIN RESULTS: Of 913 potential studies, 10 trials were identified with a total of 918 participants, four of which are in progress or awaiting publication. The remaining six trials were suitable for consideration by this review (344 participants). Only two trials met our protocol's inclusion criteria. The four remaining trials were excluded as they did not use outcome measures specified in our review (2 trials, 122 participants), or were of insufficient methodological quality (2 trials, 34 participants). From the two included trials (168 participants) there was a reduction in relapse rate and increased time to first relapse during treatment with intravenous immunoglobulins, but reliable disease progression outcomes were not reported, nor were magnetic resonance imaging (MRI) data available to support clinical information. There may be as many as 574 participants in ongoing or yet to be published trials. REVIEWER'S CONCLUSIONS: There is some evidence to support use of intravenous immunoglobulins as a preventative treatment for relapses in relapsing remitting MS, but further studies should be performed using MRI and disease progression endpoints. It may be possible to draw more robust conclusions when ongoing or recently completed trials make their data available for review. Two rigorously conducted trials with a total of 122 participants did not demonstrate a positive clinical benefit, but were excluded from this review as they employed outcome measures not specified in our protocol. Immunoglobulins were well tolerated with a less than 5% risk of adverse events in participants in included trials.

Humans↗
PubMed2002

Relationship between ion pair geometries and electrostatic strengths in proteins.

The electrostatic free energy contribution of an ion pair in a protein depends on two factors, geometrical orientation of the side-chain charged groups with respect to each other and the structural context of the ion pair in the protein. Conformers in NMR ensembles enable studies of the relationship between geometry and electrostatic strengths of ion pairs, because the protein structural contexts are highly similar across different conformers. We have studied this relationship using a dataset of 22 unique ion pairs in 14 NMR conformer ensembles for 11 nonhomologous proteins. In different NMR conformers, the ion pairs are classified as salt bridges, nitrogen-oxygen (N-O) bridges and longer-range ion pairs on the basis of geometrical criteria. In salt bridges, centroids of the side-chain charged groups and at least a pair of side-chain nitrogen and oxygen atoms of the ion-pairing residues are within a 4 A distance. In N-O bridges, at least a pair of the side-chain nitrogen and oxygen atoms of the ion-pairing residues are within 4 A distance, but the distance between the side-chain charged group centroids is greater than 4 A. In the longer-range ion pairs, the side-chain charged group centroids as well as the side-chain nitrogen and oxygen atoms are more than 4 A apart. Continuum electrostatic calculations indicate that most of the ion pairs have stabilizing electrostatic contributions when their side-chain charged group centroids are within 5 A distance. Hence, most (approximately 92%) of the salt bridges and a majority (68%) of the N-O bridges are stabilizing. Most (approximately 89%) of the destabilizing ion pairs are the longer-range ion pairs. In the NMR conformer ensembles, the electrostatic interaction between side-chain charged groups of the ion-pairing residues is the strongest for salt bridges, considerably weaker for N-O bridges, and the weakest for longer-range ion pairs. These results suggest empirical rules for stabilizing electrostatic interactions in proteins.

Biophysical Phenomena↗
PubMed2003

Comparison of statistically derived ASAS improvement criteria for ankylosing spondylitis with clinically relevant improvement according to an expert panel.

OBJECTIVE: To investigate whether the recently developed (statistically derived) "ASsessment in Ankylosing Spondylitis Working Group" improvement criteria (ASAS-IC) for ankylosing spondylitis (AS) reflect clinically relevant improvement according to the opinion of an expert panel. METHODS: The ASAS-IC consist of four domains: physical function, spinal pain, patient global assessment, and inflammation. Scores on these four domains of 55 patients with AS, who had participated in a non-steroidal anti-inflammatory drug efficacy trial, were presented to an international expert panel (consisting of patients with AS and members of the ASAS Working Group) in a three round Delphi exercise. The number of (non-)responders according to the ASAS-IC was compared with the final consensus of the experts. The most important domains in the opinion of the experts were identified, and also selected with discriminant analysis. A number of provisional criteria sets that best represented the consensus of the experts were defined. Using other datasets, these clinically derived criteria sets as well as the statistically derived ASAS-IC were then tested for discriminative properties and for agreement with the end of trial efficacy by patient and doctor. RESULTS: Forty experts completed the three Delphi rounds. The experts considered twice as many patients to be responders than the ASAS-IC (42 v 21). Overall agreement between experts and ASAS-IC was 62%. Spinal pain was considered the most important domain by most experts and was also selected as such by discriminant analysis. Provisional criteria sets with an agreement of >or=80% compared with the consensus of the experts showed high placebo response rates (27-42%), in contrast with the ASAS-IC with a predefined placebo response rate of 25%. All criteria sets and the ASAS-IC discriminated well between active and placebo treatment (chi(2)=36-45; p<0.001). Compared with the end of trial efficacy assessment, the provisional criteria sets showed an agreement of 71-82%, sensitivity of 67-83%, and specificity of 81-88%. The ASAS-IC showed an agreement of 70%, sensitivity of 62%, and specificity of 89%. CONCLUSION: The ASAS-IC are strict in defining response, are highly specific, and consequently show lower sensitivity than the clinically derived criteria sets. However, those patients who are considered as responders by applying the ASAS-IC are acknowledged as such by the expert panel as well as by patients' and doctors' judgments, and are therefore likely to be true responders.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2006

An automated labeling system for subdividing the human cerebral cortex on MRI scans into gyral based regions of interest.

In this study, we have assessed the validity and reliability of an automated labeling system that we have developed for subdividing the human cerebral cortex on magnetic resonance images into gyral based regions of interest (ROIs). Using a dataset of 40 MRI scans we manually identified 34 cortical ROIs in each of the individual hemispheres. This information was then encoded in the form of an atlas that was utilized to automatically label ROIs. To examine the validity, as well as the intra- and inter-rater reliability of the automated system, we used both intraclass correlation coefficients (ICC), and a new method known as mean distance maps, to assess the degree of mismatch between the manual and the automated sets of ROIs. When compared with the manual ROIs, the automated ROIs were highly accurate, with an average ICC of 0.835 across all of the ROIs, and a mean distance error of less than 1 mm. Intra- and inter-rater comparisons yielded little to no difference between the sets of ROIs. These findings suggest that the automated method we have developed for subdividing the human cerebral cortex into standard gyral-based neuroanatomical regions is both anatomically valid and reliable. This method may be useful for both morphometric and functional studies of the cerebral cortex as well as for clinical investigations aimed at tracking the evolution of disease-induced changes over time, including clinical trials in which MRI-based measures are used to examine response to treatment.

Adult↗
PubMed1999

British Hyperbaric Association carbon monoxide database, 1993-96.

OBJECTIVES: To study the referral pattern of patients, poisoned with carbon monoxide and subsequently transferred to British hyperbaric oxygen facilities, from April 1993 until March 1996 inclusive. METHODS: A standard dataset was used by hyperbaric facilities within the British Hyperbaric Association. The data on each patient were sent in confidence to the Hyperbaric Unit at Whipps Cross Hospital for analysis. The epidemiology of poisoning and the population studied were analysed. Times of removal from exposure, referral to a hyperbaric facility, arrival at the hyperbaric facility, and start of treatment were recorded. Data on the outcome of the episode were documented in one of the contributing facilities. RESULTS: 575 patients exposed to carbon monoxide were reported as being referred to British hyperbaric facilities in the three years, the busiest facilities being in London and Peterborough. The proportions of accidental and non-accidental exposures were 1:1.05. Of the accidental exposures, central heating faults were responsible in 71.5% of cases (n = 206). Smoke inhalation from fires was responsible for a further 13.5% (n = 39). The mean delay to arrival in a hyperbaric oxygen facility was 9 hours and 15 minutes after removal from exposure. Recovery after treatment was sometimes incomplete. CONCLUSIONS: The reported pattern of referral was regionally weighted towards the south east of England. Smoke inhalation victims were often not referred for hyperbaric oxygen treatment. The delay to treatment was multifactorial; and the mean delay was well in excess of six hours. There is room for improvement in the consistency and speed of referral. Treatment schedules require standardisation. A central advice and referral service would be helpful.

Adolescent↗
PubMed2002

Rat Genome Database (RGD): mapping disease onto the genome.

The Rat Genome Database (RGD, http://rgd.mcw.edu) is an NIH-funded project whose stated mission is 'to collect, consolidate and integrate data generated from ongoing rat genetic and genomic research efforts and make these data widely available to the scientific community'. In a collaboration between the Bioinformatics Research Center at the Medical College of Wisconsin, the Jackson Laboratory and the National Center for Biotechnology Information, RGD has been created to meet these stated aims. The rat is uniquely suited to its role as a model of human disease and the primary focus of RGD is to aid researchers in their study of the rat and in applying their results to studies in a wider context. In support of this we have integrated a large amount of rat genetic and genomic resources in RGD and these are constantly being expanded through ongoing literature and bulk dataset curation. RGD version 2.0, released in June 2001, includes curated data on rat genes, quantitative trait loci (QTL), microsatellite markers and rat strains used in genetic and genomic research. VCMap, a dynamic sequence-based homology tool was introduced, and allows researchers of rat, mouse and human to view mapped genes and sequences and their locations in the other two organisms, an essential tool for comparative genomics. In addition, RGD provides tools for gene prediction, radiation hybrid mapping, polymorphic marker selection and more. Future developments will include the introduction of disease-based curation expanding the curated information to cover popular disease systems studied in the rat. This will be integrated with the emerging rat genomic sequence and annotation pipelines to provide a high-quality disease-centric resource, applicable to human and mouse via comparative tools such as VCMap. RGD has a defined community outreach focus with a Visiting Scientist program and the Rat Community Forum, a web-based forum for rat researchers and others interested in using the rat as an experimental model. Thus, RGD is not only a valuable resource for those working with the rat but also for researchers in other model organisms wishing to harness the existing genetic and physiological data available in the rat to complement their own work.

Animals↗
PubMed1999

European system for cardiac operative risk evaluation (EuroSCORE).

OBJECTIVE: To construct a scoring system for the prediction of early mortality in cardiac surgical patients in Europe on the basis of objective risk factors. METHODS: The EuroSCORE database was divided into developmental and validation subsets. In the former, risk factors deemed to be objective, credible, obtainable and difficult to falsify were weighted on the basis of regression analysis. An additive score of predicted mortality was constructed. Its calibration and discrimination characteristics were assessed in the validation dataset. Thresholds were defined to distinguish low, moderate and high risk groups. RESULTS: The developmental dataset had 13,302 patients, calibration by Hosmer Lemeshow Chi square was (8) = 8.26 (P < 0.40) and discrimination by area under ROC curve was 0.79. The validation dataset had 1479 patients, calibration Chi square (10) = 7.5, P < 0.68 and the area under the ROC curve was 0.76. The scoring system identified three groups of risk factors with their weights (additive % predicted mortality) in brackets. Patient-related factors were age over 60 (one per 5 years or part thereof), female (1), chronic pulmonary disease (1), extracardiac arteriopathy (2), neurological dysfunction (2), previous cardiac surgery (3), serum creatinine >200 micromol/l (2), active endocarditis (3) and critical preoperative state (3). Cardiac factors were unstable angina on intravenous nitrates (2), reduced left ventricular ejection fraction (30-50%: 1, <30%: 3), recent (<90 days) myocardial infarction (2) and pulmonary systolic pressure >60 mmHg (2). Operation-related factors were emergency (2), other than isolated coronary surgery (2), thoracic aorta surgery (3) and surgery for postinfarct septal rupture (4). The scoring system was then applied to three risk groups. The low risk group (EuroSCORE 1-2) had 4529 patients with 36 deaths (0.8%), 95% confidence limits for observed mortality (0.56-1.10) and for expected mortality (1.27-1.29). The medium risk group (EuroSCORE 3-5) had 5977 patients with 182 deaths (3%), observed mortality (2.62-3.51), predicted (2.90-2.94). The high risk group (EuroSCORE 6 plus) had 4293 patients with 480 deaths (11.2%) observed mortality (10.25-12.16), predicted (10.93-11.54). Overall, there were 698 deaths in 14,799 patients (4.7%), observed mortality (4.37-5.06), predicted (4.72-4.95). CONCLUSION: EuroSCORE is a simple, objective and up-to-date system for assessing heart surgery, soundly based on one of the largest, most complete and accurate databases in European cardiac surgical history. We recommend its widespread use.

Cardiac Surgical Procedures↗
PubMed1995

Use of Spanish surnames to identify Latinos: comparison to self-identification.

Difficulties in identification of Latinos from secondary datasets have often been addressed by the use of a Spanish surname list. To evaluate the sensitivity and specificity of the 1980 U.S. Census Spanish surname list in correctly identifying Latino ethnicity, we conducted a cross-sectional survey of adult members of a prepaid health plan in the San Francisco Bay Area. We compared a randomly selected list of 1345 Spanish surnames and 717 non-Spanish surnames from health plan membership lists with their self-identified race and ethnicity obtained by telephone interviews. The sample was stratified according to surname group (Spanish or non-Spanish), sex, age, and county. Compared with self-identified ethnicity, a Spanish surname was 88.4% sensitive in identifying Latino men and 70.4% sensitive in identifying Latina women. The non-Spanish surname list was 94.1% sensitive and 95.0% specific in correctly identifying non-Latinos. Although the overall negative predictive value was 97.8%, the positive predictive value of a Spanish surname was only 68.3% for men and 55.7% for women. The low positive predictive value was largely due to the 316 (61%) Filipinos among the 517 persons with Spanish surnames who were not Latinos. We conclude that the use of the Spanish surname list alone to ascertain race and ethnicity in the San Francisco Bay Area both falsely identifies a large number of non-Latino persons as Latino and fails to identify a small proportion of Latinos. Although the level of sensitivity and specificity for Spanish surnames will vary with the area under study, this source of inaccuracy must be considered in studies that plan to use data based on Spanish surnames.

Adult↗
PubMed1999

Transthoracic 3-dimensional echocardiography in the assessment of subaortic stenosis due to a restrictive ventricular septal defect in double inlet left ventricle with discordant ventriculoarterial connections.

UNLABELLED: To evaluate the accuracy and clinical utility of three-dimensional echocardiography in the assessment of the size and shape of the ventricular septal defect in double inlet left ventricle. METHODS: We validated the technique in an autopsy study, and then performed a clinical investigation. Six autopsied hearts were immersed in a waterbath and examined with 3-dimensional echocardiography. We identified the cross-section within the dataset which optimally displayed the ventricular septal defect "en face", and compared its smallest and largest diameters, as well as its area. The ventricular septal defect was then filled with a silicone sealant and a section prepared for direct measurement. In patients, we measured the diameters and area of the ventricular septal defect in endsystole nad computed the aortic valvar area in endsystole from the cross-section showing the aortic valve "en face". Ten patients with double inlet left ventricle, aged between 2 and 15 years, were studied using rotational or parallel scanning. All patients had undergone banding of the pulmonary trunk at a mean age of 7 (3-36) days, usually at the time of repair of the coarctation. Two patients had undergone surgical enlargement of the ventricular septal defect prior to echocardiographic examination. RESULTS: The correlation between the areas of the ventricular septal defect in the specimens measured directly and by 3-dimensional echocardiography was r=0.98, with limits of agreement between -0.1-0.08 cm2. In the patients, the area of the defect was measured as 3.9+/-2 cm2, whereas the aortic valvar area was 2.6+/-0.9 cm2. The ratio between the areas was 1.5 (0.5-2.3). Three patients with areas of the ventricular septal defect smaller than those of the aortic valve had resting Doppler gradients between double inlet left ventricle and the aorta of 16, 20 and 30 mm Hgs, respectively. CONCLUSIONS: 3-dimensional echocardiography provides accurate assessment of the area of the ventricular septal defect in double inlet left ventricle, and is helpful in identifying patients with subaortic stenosis caused by restrictive defects.

Adolescent↗
PubMed2004

A statistical simulation study finds discordance between WHO criteria and RECIST guideline.

OBJECTIVE: Tumor shrinkage has been adopted as an end point for evaluating the effectiveness of new anticancer agents. The WHO (World Health Organization) criterion suggested measuring the tumor shrinkage by the change in the product of maximal diameter (MD) and the corresponding largest perpendicular diameter (LPD). The RECIST (Response Evaluation Criteria In Solid Tumor) guideline proposed using the change in MD only, based on the observation that this measure is more linearly related to tumor cell kill than the cross product (MD*LPD). Both criteria classify patients into four categories of response: complete response (CR: total disappearance), partial response (PR), stable disease (SD), and progressive disease (PD) but the criteria used in the definition of PD vary. It was anticipated that patients' actual response categorization would not be considerably affected by utilizing the RECIST criteria instead of WHO. Empirical evidence supporting this fact was provided by retrospective analysis of several large datasets. STUDY DESIGN AND SETTING: A statistical simulation is performed to generate tumor measurements and patient response data under meaningful probability distributions with parameters based on data from 130 patients on clinical trials at a cancer center. Concordance measures between the two response criteria (Kappa coefficient and percentage disagreement per response category) are assessed systematically over various combinations of the percentage of elliptical tumors at baseline and the percentage of tumors changing shape from baseline to follow-up. RESULTS: The overall percentage of disagreement between the two methods of response assessment is found to be in the range of 14-20%. The patients categorized by WHO in the PR, SD, and PD groups fall into a different category when assessed by RECIST between 8-16%, 3-12%, and 32-35% of the times, respectively. The kappa coefficient ranges between 0.68-0.77. The proportion of elliptical tumors at baseline does not greatly impact the concordance, but the magnitude of the change in the aspect ratio has a large impact. CONCLUSION: Response assessment as measured by RECIST, with both a change in the underlying metric and change in definition of progression, often results in different categorization of response compared to WHO. The difference in response categorization may be problematic when new experimental therapies are compared to conventional agents whose response rates have been established in historical trials. The apparent lower rate of disease progression with RECIST may mean that more patients remain on therapy. Higher percentages of patients with SD need to be interpreted cautiously by distinguishing those due to the change in the response criterion as opposed to those induced by drugs using pathways such as angiogenesis where disease stabilization is expected rather than shrinkage of tumor.

Antineoplastic Agents↗
PubMed2005

Cost-effectiveness of leucocyte-depleted erythrocyte transfusion in cardiac valve surgery.

Cost-effectiveness of leucodepleted erythrocytes (LD) over buffy-coat-depleted packed cells (PC) is estimated from the primary dataset of a recently reported randomized clinical trial involving valve surgery (+/-CABG) patients. Data on the patient level of 474 adult patients who were randomized double-blind to LD or PC were used in order to calculate the healthcare costs and longevity per patient. The incremental cost-effectiveness ratio (ICER) in net costs per life-year gained was established from the healthcare perspective. Bootstrapping and cost-effectiveness acceptability curves were used in order to determine the confidence interval (CI) of the ICER. The longevity of patients in the PC and LD group was 10.6 and 11.4 years, respectively. Relative to PC, LD yielded an estimated 0.8 (95% CI = -0.27 to 1.84) life-year in the baseline. Adjusted for age and sex differences, health gains for LD are 0.4 life-year gained (95% CI = -0.67 to 1.44). Healthcare costs per patient averaged 10163 US dollars per patient in the PC group and 9949 US dollars in the LD group. Average cost-savings were 214 US dollars (95% CI = -1536 to 1964) per patient. Acceptability curves constructed from bootstrap simulations showed a probability of being cost-saving of 59% for universal leucodepletion from the healthcare perspective. The probability of adopting leucodepletion regardless of the costs reaches 92.7%. LD in patients receiving four or more transfusions showed the highest cost-savings and health gains. Leucodepletion of erythrocytes is a cost-saving strategy in cardiac valve (+/-CABG) patients. However, probablistic analysis failed to show a significant difference with buffy-coat-depleted PC.

Aged↗
PubMed2003

Improvement in quality of colorectal cancer pathology reporting with a standardized proforma--a comparative study.

BACKGROUND: Histopathological evaluation is a critical component in the management of patients with colorectal cancer (CRC). It is the single most powerful prognostic indicator in CRC and determines if adjuvant chemotherapy is indicated. The aim of this study was to assess if the introduction of a comprehensive standardized pathology proforma improved the quality of histopathology reporting. METHODS: A standardized pathology proforma, based on the 1996 minimum dataset for colorectal histopathology reporting, was introduced in our pathology department in 1998. Pathology reports for all colonic resection specimens for 1996 (n = 85) and 2000 (n = 86) were identified, retrieved and entered on to database. Comparison was made with the minimum dataset published in the 1996 guidelines for the management of colorectal cancer. RESULTS: Demographic details were complete in all cases. Clinical data was incomplete in 57 (67%) patients in 1996 and 63 (73%) in 2000 (ns; chi2). There were 24 (28%) (7 Abdomino-perineal resections (APER)) and 40 (47%) (17 APER's) rectal specimens for 1996 and 2000, respectively. The presence or absence of pathological background abnormalities were commented on in 18 (21%) reports in 1996 and 80 (93%) reports in 2000 (P < 0.01; Fishers exact test (Fisher)). Histological differentiation was commented on in 73 (86%) and 86 (100%) in 1996 and 2000, respectively (P < 0.01; Fisher). Dukes' stage was stated in 33 (39%) reports in 1996 and 86 (100%) in 2000 (P < 0.01; Fisher) but Dukes' stage was calculable in 84 (99%) in 1996 and 86 reports (100%) for 2000 (ns; Fisher). The apical node was commented on in 34 (40%) reports in 1996 and 85 (99%) reports in 2000 (P < 0.01; Fisher). The median (IQR) number of nodes assessed in 1996 was 8 (5-12) compared to 12 (8-17) in 2000 (P < 0.001; Mann-Whitney (MW)). Complete resection was mentioned in 74 (87%) reports in 1996 and 86 (100%) in 2000 (P < 0.01; Fisher). Regarding rectal specimens, the circumferential resection margin (CRM) was commented on in 19 of 24 specimens in 1996 and 38 of 40 specimens in 2000 (ns; Fisher). Relationship to the peritoneal reflection was commented on in 1 (1%) rectal specimen in 1996 and 30 (35%) in 2000 (P < 0.001; Fisher). CONCLUSION: The introduction of a standardized proforma for reporting CRC resection specimens improves the quality of histopathological reporting. This aids decision-making regarding adjuvant chemotherapy or radiotherapy and further surveillance.

Colorectal Neoplasms↗
PubMed2004

Three new consensus QSAR models for the prediction of Ames genotoxicity.

Three QSAR methods, artificial neural net (ANN), k-nearest neighbors (kNN), and Decision Forest (DF), were applied to 3363 diverse compounds tested for their Ames genotoxicity. The ratio of mutagens to non-mutagens was 60/40 for this dataset. This group of compounds includes >300 therapeutic drugs. All models were developed using the same initial set of 148 topological indices: molecular connectivity chi indices and electrotopological state indices (atom-type, bond-type and group-type E-state), as well as binary indicators. While previous studies have found logP to be a determining factor in genotoxicity, it was not found to be important by any modeling method employed in this study. The three models yielded an average training/test concordance value of 88%, with a low percentage of false positives and false negatives. External validation testing on 400 compounds not used for QSAR model development gave an average concordance of 82%. This value increased to 92% upon removal of less reliable outcomes, as determined by a reliability criterion used within each model. The ANN model showed the best performance in predicting drug compounds, yielding 97% concordance (34/35 drugs) after the removal of less reliable predictions. The appreciable commonality found among the top 10 ranked descriptors from each model is of particular interest because of the diversity in the learning algorithms and descriptor selection techniques employed in this study. Forty percent of the most important descriptors in any one model are found in one or two other models. Fourteen of the most important descriptors relate directly to known toxicophores involved in potent genotoxic responses in Salmonella typhimurium. A comparison of the validation results with those of MULTICASE and DEREK indicated that the new models presented in this work perform substantially better than the former models in predicting genotoxicity of therapeutic drugs. Substantially higher specificity was achieved with these new models as compared with MULTICASE or DEREK with comparable sensitivities among all models.

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