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PubMedDate not supplied

Reliability of self-reported breast screening information in a survey of lower income women.

BACKGROUND: Self-reported behavior is widely used to estimate the prevalence of breast cancer screening and to evaluate programs for promoting screening, but detailed studies of reliability have not previously been performed. METHODS: Reliability was assessed by comparing responses to questions about screening behavior from repeat personal interviews of 382 women age 40 and older living in low-income census tracts of two Florida communities. Reliability was assessed using Pearson's correlation (r) and kappa (kappa) coefficients. RESULTS: Estimated reliabilities were kappa = 0.38 for "ever had clinical breast examination," kappa = 0.82 for "ever had mammogram," kappa = 0.65 for "mammogram in past year," r = 0.54 for "date of last mammogram," and r = 0.72 for "number of mammograms." The dates of last mammogram reported at the two interviews agreed within 1 month for 64% of the women, while the dates of last clinical breast examination agreed within 1 month for 50% of the women. Reliability of "ever had mammogram" was significantly related to demographic variables. CONCLUSIONS: Women reliably report ever having mammography, but information about timing and frequency has lower reliability. The results have implications for breast screening research because measurement error affects the precision of estimates and the sample sizes needed to detect program effects.

Adult↗
PubMed1990

"Rainbow reviews." IV: Recent publications of the National Center for Health Statistics.

I am always impressed at the wealth of interesting and useful information available from the NCHS, if one knows where to look. The Center tries to adapt to the changing needs of the potential users of their data, including health planners and policy analysts, and academicians. This is illustrated by the increasing emphasis on medical care utilization, especially in long term care, on disease prevention and health promotion issues and on international comparisons. Clinical investigators should be familiar with the NCHS reports, if only to avoid duplication of effort. But beyond that, the information they present can be used to develop hypotheses, estimate variances for sample size determinations, and provide useful model instruments and methods. Beyond that, the NCHS does not analyze and report exhaustively on these data, if only because of lack of resources, so that it makes most of these data available for further research at a nominal charge. Many doctoral dissertations have been based on these tapes as the primary data source for detailed content analysis and/or for methodologic innovation.

Government Publications as Topic↗
PubMed2026

Inavolisib for PIK3CA-mutated advanced endometrial cancer: a multicentric, phase II, MITO END-4 trial.

BACKGROUND: The phosphatase and tensin homolog-phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) pathway is frequently altered in gynecological tumors, notably in endometrial cancer where PIK3CA mutations are found in nearly half of patients. Despite this, evidence of clinical activity of PI3K inhibitors in endometrial cancer is poor and limited. Alpelisib, an oral PI3K alpha-selective inhibitor, showed encouraging preliminary activity in advanced gynecological tumors harboring PIK3CA alterations. Inavolisib is a highly potent and selective PI3K inhibitor. PRIMARY OBJECTIVE(S): The MITO END-4 trial aims to assess the efficacy and safety of inavolisib in patients with endometrial cancer who have received platinum-based chemotherapy and immunotherapy. The primary objective is to determine the anti-tumor activity (assessed by objective response rate) of inavolisib in patients with advanced endometrial cancer with PIK3CA mutated tumors. STUDY HYPOTHESIS: The study tests the hypothesis that inavolisib has superior anti-tumor activity compared to historically available standard therapies in previously treated patients with advanced endometrial cancer harboring a PIK3CA mutation. TRIAL DESIGN: This is a phase II, single-arm, multicenter trial in which advanced endometrial cancer patients whose tumors harbor a pathogenic PIK3CA mutation will receive inavolisib. MAJOR INCLUSION/EXCLUSION CRITERIA: Patients aged 18 years and older with documented evidence of PIK3CA mutated advanced endometrial cancer (endometrioid, serous, clear cell, carcinosarcoma or mixed histology) will be enrolled. Patients have previously received at least 1 platinum-based chemotherapy in any setting (adjuvant or advanced) with or without immune checkpoint inhibitor, alone or in combination. Not more than 4 lines of therapy are allowed. Key exclusion criteria include uterine sarcoma and prior treatment with any PI3K, AKT, or mechanistic target of rapamycin (mTOR) inhibitor. PRIMARY ENDPOINT(S): Objective response rate defined as a complete response or partial response by the Investigator using RECIST v1.1 criteria over the whole treatment period. SAMPLE SIZE: 48 patients. ESTIMATED DATES FOR COMPLETING ACCRUAL: May 2028. TRIAL REGISTRATION: MITO END-4; EU-CT NUMBER: 2025-522981-61-00; NCT07522697.

Endometrial cancer↗
PubMed2006

Preventing familial amyotrophic lateral sclerosis: is a clinical trial feasible?

OBJECTIVE: To evaluate the feasibility of a clinical trial designed to delay or prevent the onset of disease amongst subjects at risk for familial amyotrophic lateral sclerosis (fALS). BACKGROUND: The success of many agents in prolonging survival in the SOD1 model of ALS has not been translated into effective therapies for patients with ALS. It is our hypothesis that a trial in fALS may reproduce the positive effects seen in fALS animals. METHODS: Pedigrees with at least two affected family members were constructed. Unaffected family members were assigned a risk status based on their relationship to affected subjects. Attitudes towards genetic testing were ascertained amongst the at-risk family members. RESULTS: We obtained data about 5,544 people (116 families) including 516 subjects with ALS (169 from SOD1 positive families) as well as 1,056 subjects "definitely" or "probably" at risk for fALS (335 from SOD1 positive families). In excess of 80% of subjects indicated an interest in participating in a future clinical trial directed at delaying the onset of the disease. Assuming the use of a therapeutic agent that will prolong the time to the onset of fALS by 50%, we estimate that a sample size of between 261 and 610 subjects 'definitely at risk' will be required (power 0.8) depending on whether patients are followed for 10 or 5 years respectively. CONCLUSIONS: A clinical trial in fALS may be feasible although such a trial would likely require prolonged follow-up and would require a therapeutic agent with a large clinical effect in order to be adequately powered.

Adolescent↗
PubMed2005

Analysis of porosity in porous silicon using hyperpolarized 129Xe two-dimensional exchange experiments.

The porosity in porous silicon was characterized using hyperpolarized (HP) xenon as a probe. HP xenon under conditions of continuous flow allows for the rapid acquisition of xenon NMR spectra that can be used to characterize a variety of materials. Two-dimensional exchange spectroscopy (EXSY) (129)Xe NMR experiments using HP xenon were performed to obtain exchange pathways and rates of xenon mobility between pores of different dimensions within the structure of porous silicon and to the gas phase above the sample. Pore sizes are estimated from chemical shift information and a model for pore geometry is presented.

Isotopes↗
PubMedDate not supplied

QT interval measurement in the dog: chest leads versus limb leads.

INTRODUCTION: An accurate measurement of the QT interval is dependent on the accurate identification of the end of the T wave. Although chest leads have been recommended in dog toxicology studies, their use has not been widely put into practice, as shown by a recent survey on methodology for ECG collection in the pharmaceutical industry. Therefore, there is little published data on dog QT measurement from chest leads. METHODS: Electrocardiograms (ECGs) were taken from 100 beagle dogs (50 males, 50 females), with the dogs restrained in a sling. On the day of recording, measurements were performed at time zero and 1 h later. Recordings were repeated 7 to 10 days later. QT interval measurements were taken simultaneously from Lead II and the chest Lead CV5RL. Heart rate was taken from Lead II. Statistical analyses included the calculation of a QT correction formula, comparison of the mean values and variability of QT and QTc measurements from Leads II and CV5RL, the comparison of T-wave polarity from both leads, and a power analysis for QT and QTc. RESULTS: The T wave was positive in almost all dogs (99/100) in the Lead CV5RL at all measurement periods, while it was either positive or negative in Lead II (64-75/100), and the incidence of positive T wave varied between measurement periods. The QT interval was significantly shorter (194+/-11 to 197+/-12 vs. 197+/-13 to 200+/-12 ms) when measured from the CV5RL lead at all recording periods and in both sexes. In addition, the standard deviation for QT measurement within each individual ECG record demonstrates less intra-animal variation when QT is measured from Lead CV5RL compared with Lead II (3.8 vs. 13.2 ms). The linear regression between QT and heart rate was improved when QT measurements were taken from CV5RL, as shown by the percentage of variability R2. DISCUSSION: Estimates of the sample sizes showed that fewer animals would be required to detect a change at both the high and the mid-doses when using the chest Lead CV5RL. Using Lead II, we are able to detect within-animal changes of 10% in either QT or QTc; with Lead CV5RL, we are able to detect 10% change in QT and 5% change in QTc.

Animals↗
PubMed2006

Evaluation of QT interval using a linear model in individual cynomolgus monkeys.

INTRODUCTION: The cynomolgus monkey, one of a number of primate species phylogenetically close to humans, is commonly used in cardiovascular research, but a method for determination of the RR interval-corrected QT interval in this species needs greater consideration. The objectives of this study were to determine a method for evaluating QT interval in cynomolgus monkeys individually, disregarding RR interval change artifacts, and to investigate prerequisite information for this method. METHODS: The physiological QT-RR relationship for practical evaluation of QT interval was recorded and analyzed by 24-hour telemetric ECG monitoring. A linear model for log-transformed QT and RR intervals was used to correct the QT interval from RR interval change artifacts for each animal. Sample size was also estimated based on the simulation results. RESULTS: Histograms showed that both QT and RR intervals had a right-heavy tail distribution. QT interval corrected individually by the linear model formula showed smaller within-animal variability than QTb and QTf, which were corrected by Bazett's formula and Fridericia's formula. The simulation results showed that the individual correction factor, beta(i), could be reliably estimated when at least 24 pairs of QT-RR baseline data were available. DISCUSSION: As with humans, QT interval in cynomolgus monkeys varies widely between individuals. Therefore, a method for correcting QT interval individually should be considered, whenever extensive untreated data are available.

Animals↗
PubMed2004

Estimation of genotype error rate using samples with pedigree information--an application on the GeneChip Mapping 10K array.

Currently, most analytical methods assume all observed genotypes are correct; however, it is clear that errors may reduce statistical power or bias inference in genetic studies. We propose procedures for estimating error rate in genetic analysis and apply them to study the GeneChip Mapping 10K array, which is a technology that has recently become available and allows researchers to survey over 10,000 SNPs in a single assay. We employed a strategy to estimate the genotype error rate in pedigree data. First, the "dose-response" reference curve between error rate and the observable error number were derived by simulation, conditional on given pedigree structures and genotypes. Second, the error rate was estimated by calibrating the number of observed errors in real data to the reference curve. We evaluated the performance of this method by simulation study and applied it to a data set of 30 pedigrees genotyped using the GeneChip Mapping 10K array. This method performed favorably in all scenarios we surveyed. The dose-response reference curve was monotone and almost linear with a large slope. The method was able to estimate accurately the error rate under various pedigree structures and error models and under heterogeneous error rates. Using this method, we found that the average genotyping error rate of the GeneChip Mapping 10K array was about 0.1%. Our method provides a quick and unbiased solution to address the genotype error rate in pedigree data. It behaves well in a wide range of settings and can be easily applied in other genetic projects. The robust estimation of genotyping error rate allows us to estimate power and sample size and conduct unbiased genetic tests. The GeneChip Mapping 10K array has a low overall error rate, which is consistent with the results obtained from alternative genotyping assays.

Computer Simulation↗
PubMed2002

Dose-range effects of propofol for reducing emetic symptoms during cesarean delivery.

OBJECTIVE: To evaluate the efficacy and safety of propofol at subhypnotic doses for reducing emetic symptoms in parturients undergoing cesarean delivery under spinal anesthesia. METHODS: In a randomized, double-masked trial, 80 patients received lidocaine intravenously 0.1 mg/kg (for injection pain relief) followed by either placebo or propofol at three different doses (0.5 mg/kg per hour, 1.0 mg/kg per hour, 2.0 mg/kg per hour) (n = 20 in each group) immediately after clamping of the umbilical cord. Emetic episodes and safety assessments were performed during spinal anesthesia for cesarean delivery. To estimate a sufficient sample size, it was calculated that 20 patients per group would be required with alpha =.05 and beta =.2. RESULTS: The rate of patients experiencing no emetic symptoms in an intraoperative, postdelivery period was 45% with propofol 0.5 mg/kg per hour (P =.5), 80% with propofol 1.0 mg/kg per hour (P =.011), and 80% with propofol 2.0 mg/kg per hour (P =.011), compared with placebo (40%). No clinically serious adverse events caused by the study drugs were observed. CONCLUSION: Propofol 1.0 mg/kg per hour is the minimum effective subhypnotic dose for reducing emetic symptoms during cesarean delivery. Increasing the dose to 2.0 mg/kg per hour provides no further benefit.

Adult↗
PubMed2002

Dexamethasone for the prevention of nausea and vomiting after dilatation and curettage: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy and safety of dexamethasone administered intravenously at three different doses (4 mg, 8 mg, 16 mg) for the prevention of nausea and vomiting after dilatation and curettage. METHODS: In a prospective, randomized, double-masked, placebo-controlled trial, 120 women received placebo or dexamethasone intravenously at doses of 4 mg, 8 mg, or 16 mg immediately before induction of anesthesia (n = 30 in each group). Propofol-based general anesthetic was used. Emetic episodes and safety assessments were performed. To estimate a sufficient sample size, it was calculated that 30 patients per group would be required with alpha =.05 and beta =.2. RESULTS: The rate of patients who were emesis-free (no nausea, retching, or vomiting) 0-24 hours after anesthesia was 57% with dexamethasone 4 mg (P =.796), 87% with dexamethasone 8 mg (P =.005), and 87% with dexamethasone 16 mg (P =.005), compared with placebo (50%). Patients who had received dexamethasone 8 mg or 16 mg were more satisfied than those who had received placebo (P <.05). No clinically important adverse events were observed in any of the groups. CONCLUSION: Dexamethasone 8 mg is an effective antiemetic for preventing postoperative nausea and vomiting 0-24 hours after anesthesia in women undergoing propofol-based general anesthesia for termination of pregnancy. Increasing the dose to 16 mg provided no additional benefit.

Adult↗
PubMed1996

Methodologic standards in surgical trials.

BACKGROUND: Concerns have been raised that flaws in the design and analysis of trials will hinder the interpretation of their relevance to clinical practice. The objective of this study was to review the nature and methodologic standards of surgical trails published in 10 prestigious journals between January 1988 and December 1994. METHODS: We evaluated the demography and methodologic standards of 364 trials. Each article was independently scrutinized by two assessors with documentation of the interassessor variation. RESULTS: Less than 50% of the trials made comment about an unbiased assessment of outcome, gave an adequate description of the randomization technique, or provided a prospective estimate of the sample size. Economic factors were declared in 6.5% of the trials. Only 2% of the trials attempted to measure the effect of an intervention on the quality of life patients. CONCLUSIONS: Readers should be cautious when interpreting the results of surgical trials.

Clinical Trials as Topic↗
PubMed1998

Maintenance chemotherapy for small cell lung cancer: a critical review of the literature.

Maintenance chemotherapy after induction therapy is a controversial topic in small cell lung cancer. We carried out a critical review of the literature on this topic. Since 1980, 13 randomized trials have been published. One shows a statistically significant difference in survival in favor of maintenance, five obtain some survival advantages in subgroups of patients, one shows a significantly shorter survival with maintenance and in six studies, there is no difference between both arms. A quantitative overview or meta-analysis was unpracticable because of the lack of data for calculation of the odds ratio in the publications and because of the heterogeneity of the studies' designs. A qualitative overview was carried out using two scales: the Chalmers scores and the European Lung Cancer Working Party (ELCWP) score. Correlation between both scores was excellent. There was no significant difference in quality scores with both methods between negative trials and those who showed some survival advantage for survival. The overall quality of the publications was not good, with important methodological aspects missing, such as a clear definition of the primary objective or an a priori estimate of the sample size necessary to conduct the trial. We concluded that maintenance chemotherapy could have some indications and that good quality trials, as reflected by very high quality scores, need to be carried out in the future.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Quality control of cancer screening examination procedures in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Investigators for the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial describe quality control procedures for the digital rectal examination, ovarian palpation examination, transvaginal ultrasound, chest X-ray, and flexible sigmoidoscopy. These cancer screening tests are subjective and difficult to standardize. PLCO quality control procedures aim to measure and, where possible, reduce variation, across examiner and screening center, with respect to cancer screening test performance. Initial protocols stressed examiner qualifications, experience, and training; equipment specifications; examination procedures; and definitions for positive tests. The PLCO quality assurance subcommittee developed a final quality assurance plan, which included central approval and registration of PLCO examiners, direct observation of screening test performance during periodic site visits by the National Cancer Institute and coordinating center auditors, periodic analysis of screening test data, and procedures for independently duplicating or reviewing selected examinations. For each modality, the periodic data analyses examine the test-positive and the test-inadequate proportions and aim to identify divergent centers or examiners. Procedures for duplicating examinations specify feasible sample sizes for precise estimates of agreement between examiners, at each center, for each screening test modality, and over a 1-year period. These quality control procedures will help characterize the consistency and reliability of the PLCO cancer screening tests.

Aged↗
PubMed1999

The accuracy of self-reported health behaviors and risk factors relating to cancer and cardiovascular disease in the general population: a critical review.

OBJECTIVE: To critically review the literature concerning the accuracy of self-reported health behaviors and risk factors relating to cancer and cardiovascular disease among the general population. METHOD: A literature search was conducted on three major health research databases: MEDLINE, HealthPLAN, and PsychLit. The bibliographies of located articles were also checked for additional relevant references. Studies meeting the following five inclusion criteria were included in the review: They were investigating the accuracy of self-report among the general population, as opposed to among clinical populations. They employed an adequate and appropriate gold standard. At least 70% of respondents consented to validation, where validation imposed minimal demands on the respondent; and 60% consent to validation was considered acceptable where validation imposed a greater burden. They had a sample size capable of estimating sensitivity and specificity rates with 95% confidence intervals of width +/-10%. The time lag between collection of the self-report and validation data for physical measures did not exceed one month. RESULTS: Twenty-four of 66 identified studies met all the inclusion criteria described above. In the vast majority, self-report data consistently underestimated the proportion of individuals considered "at-risk." Similarly, community prevalences of risk factors were considerably higher according to gold standard data sources than they were according to self-report data. CONCLUSIONS: This review casts serious doubts on the wisdom of relying exclusively on self-reported health information. It suggests that caution should be exercised both when trying to identify at-risk individuals and when estimating the prevalence of risk factors among the general population. The review also suggests a number of ways in which the accuracy of individuals' self-reported health information can be maximized.

Cardiovascular Diseases↗
PubMed1994

The frequency of culturing stools from adults with diarrhoea in Great Britain.

Utilizing the Office of Population Censuses and Surveys (OPCS) Omnibus Survey, it was possible to measure the frequency with which a stool culture was obtained following episodes of diarrhoea in adults. Interviewing over 8000 adults, over a 4-month period between October 1992 and January 1993, 633 persons (7.9%) reported one episode of diarrhoea in the previous month, and 5.4% of these individuals with diarrhoea reported that a stool had been requested for examination. No significant regional differences were observed with the sample size available. The estimate of the rate of diarrhoea in adults was just under one episode per person per year.

Adolescent↗
PubMed2003

Therapists as fixed versus random effects-some statistical and conceptual issues: a comment on Siemer and Joormann (2003).

The authors disagree with M. Siemer and J. Joormann's assertion that therapist should be a fixed effect in psychotherapy treatment outcome studies. If treatment is properly standardized, therapist effects can be examined in preliminary tests and the therapist term deleted from analyses if such differences approach zero. If therapist effects are anticipated and either cannot be minimized through standardization or are specifically of interest because of the nature of the research question, the study has to be planned with adequate statistical power for including therapist as a random term. Simulation studies conducted by Siemer and Joormann confounded bias due to small sample size and inconsistent estimates.

Analysis of Variance↗
PubMed1999

Evaluation of screening for nasopharyngeal carcinoma: trial design using Markov chain models.

In this paper, we develop a Markov chain model to estimate parameters pertaining to the natural history of nasopharyngeal carcinoma (NPC). The model is of progression from no disease to Epstein-Barr virus (EBV) infection, preclinical screen-detectable tumour and clinical tumour. We derive tentative estimates of the parameters of the model, based on limited published data, to assess the efficacy of serum screening in conjunction with clinical assessment (indirect mirror examination for NPC), for example the average duration of the preclinical screen-detectable phase is estimated as 3.1 years. We further apply these parameters to a hypothetical screening trial in the Hong Kong population to assess the efficacy of serum screening with clinical assessment by different combinations of screening regime. Results suggest: (1) there is no substantial difference between 3-yearly and 6-yearly serum screening; and (2) within the same serum screening regime annual and 3-yearly clinical assessment can prevent 33% and 28% of deaths from NPC respectively. Prediction of deaths and surrogate end points can be used to estimate the required sample size and duration for designing a randomized trial of screening for NPC. Based on these findings and power projections, we suggest a design for a randomized trial in a high incidence area such as Hong Kong.

Disease Progression↗