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At least 127 records · Page 7Linked to original sources
PubMed2005

Population characteristics in cervical cancer trials: search for external validity.

OBJECTIVE: The purpose of this study was to compare the characteristics of patients with cervical cancer who were enrolled in cooperative group trials with characteristics of the cervical cancer population of the United States and to determine the generalizability of the results of those trials to the disease population in the United States. STUDY DESIGN: Phase III trials in cervical cancer that were conducted by cooperative groups in the United States from 1981 through 1997 were identified. These groups were placed into 4 categories on the basis of disease stage and primary treatment modality: Stage IB, negative pelvic nodes that were treated with radical hysterectomy (n = 277 patients); Stage IB-IIA, positive pelvic nodes that were treated with radical hysterectomy (n = 239 patients); Stage IB 2 , negative pelvic and para-aortic nodes that were treated with radiation therapy (n = 369 patients); and Stage IIB-IVA, negative para-aortic nodes that were treated with radiation therapy (n = 1190 patients). For each category, comparable patients from the Surveillance, Epidemiology, and End Results (SEER) database were identified. The age and ethnic distributions of each study population and the distributions of the SEER program were compared. RESULTS: The age distributions were equivalent, except for patients with IB 2 disease that was treated with radiation therapy where cooperative group subjects were more likely to be younger than 50 years, (odds ratio, 0.17; 95% CI, 0.11-0.26). A statistically significant higher proportion of black and Hispanic women enrolled in cooperative group studies in comparison with surveillance, epidemiology, and end results. CONCLUSION: Hispanic and black women were recruited proportionately to cooperative group randomized cervical cancer trials in comparison to the United States population. The age distribution of the clinical trial population is also comparable to that of the general population.

Adult↗
PubMed2005

Exploring the boundaries of memory distrust from repeated checking: increasing external validity and examining thresholds.

Checking behavior is among the most common forms of compulsions in OCD. Recent research suggests that repeated checking decreases memory confidence, and supports theoretical models of how repeated checking is maintained. The current paper presents findings from two studies exploring the boundaries of memory distrust from repeated checking. Results of study 1 show that repeated checking of a real stove decreases memory confidence, vividness, and detail (i.e., metamemory), and leads to a greater reliance on knowing as a source of memory, without meaningfully altering memory accuracy. Results of study 2 suggest that these changes in metamemory are observed after performing a relatively low number of checks on one occasion. The findings are considered within the context of theoretical models of checking and future directions are delineated.

Adolescent↗
PubMed2004

The external validity of results derived from ecstasy users recruited using purposive sampling strategies.

This study sought to compare the patterns and correlates of 'recent' and 'regular' ecstasy use estimated on the basis of two datasets generated in 2001 in New South Wales, Australia, from a probability and a non-probability sample. The first was the National Drug Strategy Household Survey (NDSHS), a multistage probability sample of the general population; and the second was the Illicit Drug Reporting System (IDRS) Party Drugs Module, for which regular ecstasy users were recruited using purposive sampling strategies. NDSHS recent ecstasy users (any use in the preceding 12 months) were compared on a range of demographic and drug use variables to NDSHS regular ecstasy users (at least monthly use in the preceding 12 months) and purposively sampled regular ecstasy users (at least monthly use in the preceding 6 months). The demographic characteristics of the three samples were consistent. Among all three, the mean age was approximately 25 years, and a majority (60%) of subjects were male, relatively well-educated, and currently employed or studying. Patterns of ecstasy use were similar among the three samples, although compared to recent users, regular users were likely to report more frequent use of ecstasy. All samples were characterised by extensive polydrug use, although the two samples of regular ecstasy users reported higher rates of other illicit drug use than the sample of recent users. The similarities between the demographic and drug use characteristics of the samples are striking, and suggest that, at least in NSW, purposive sampling that seeks to draw from a wide cross-section of users and to sample a relatively large number of individuals, can give rise to samples of ecstasy users that may be considered sufficiently representative to reasonably warrant the drawing of inferences relating to the entire population. These findings may partially offset concerns that purposive samples of ecstasy users are likely to remain a primary source of ecstasy-related information.

Adolescent↗
PubMedDate not supplied

Turning theory into practice: rationale, feasibility and external validity of an exploratory randomized controlled trial of training family practitioners in reattribution to manage patients with medically unexplained symptoms (the MUST).

BACKGROUND: The evidence for the effectiveness of reattribution training are limited, and optimal service delivery is not yet established. OBJECTIVES: The objectives of this study were to establish the feasibility and to optimize the service delivery and design of a definitive randomized controlled trial (RCT) of reattribution training for patients with medically unexplained symptoms (MUSs) in routine primary care. METHODOLOGY: The study was of a cluster RCT design with the practice as the unit of randomization. Health facilitator (HF)-delivered reattribution training was compared with no reattribution training. The primary outcome measure used is doctor-patient communication in the consultation. Quantitative and qualitative methods identify barriers to effectiveness. The acceptability and feasibility of the intervention were established by attendance rates and postal survey after completion of training. RESULTS: Sixteen practices and 70 family practitioners (FPs) were recruited with representative practice and FP characteristics. Six hours of HF reattribution training to FPs in the workplace proved feasible and acceptable with all 35 FPs completing the training. Feedback from 27 (77%) FPs who received training indicated that 25 (93%) FPs believed that specific and relevant learning achievements were made, 22 (82%) felt more confident and 21 (77%) thought the training was useful. CONCLUSION: HF-delivered reattribution training to whole practices is feasible and acceptable, and its effectiveness is measurable in routine primary care.

Adult↗
PubMed2006

External validation of the Glasgow Aneurysm Score to predict outcome in elective open abdominal aortic aneurysm repair.

OBJECTIVES: Selecting patients based on their risk profiles could improve the outcome after elective surgery of an abdominal aortic aneurysm (AAA). The Glasgow Aneurysm Score (GAS) is a scoring system developed to determine such risk profiles. In other settings, the GAS has proved to have a predictive value for the postoperative outcome. The aim of this study was to investigate whether the GAS was also valid for the patients in our hospital and to examine risk factors with a possible predictive value for postoperative mortality and morbidity. METHODS: We performed a retrospective cohort study in a university hospital. The medical records of 229 patients who underwent open elective repair for an AAA in the period 1994 to 2003 were retrospectively analyzed to assess the GAS and to determine which of the examined risk factors had a predictive value for the prognosis. RESULTS: Five patients (2.2%) died after surgery and 30 (13.1%) had a major complication. The GAS was predictive for postoperative death (P = .021; sensitivity, 1.00; 95% confidence interval [CI], 0.52 to 1.00; specificity, 0.67; 95% CI, 0.61 to 0.73) and also for major morbidity (P = .029; sensitivity, 0.63; 95% CI, 0.46 to 0.78; specificity, 0.70; 95% CI, 0.64 to 0.76). The positive predictive value (mortality, 0.06; morbidity, 0.24) and the positive likelihood ratio (mortality, 3.07; morbidity, 2.14) were low, however. The best cutoff value for the GAS was determined at 77. All the deceased patients (100%) and 63.3% of those who had a major complication had a risk score of >or=77. Of all examined risk factors, suprarenal clamping during surgery was predictive of in-hospital mortality (8.3%, P = .017). For major morbidity, three risk factors, all of which are components of the GAS, were predictive: age (P = .046), cardiac disease (P = .032), and renal disease (P = .041). CONCLUSIONS: The Glasgow Aneurysm Score has a predictive value for outcome after open elective AAA repair. Because of its relatively low positive predictive value for death and major morbidity, the GAS is of limited value in clinical decision-making for the individual high-risk patient. In some particular cases, however, the GAS can be a useful tool, especially for low-risk patients because it has good negative predictive value for this group. Suprarenal clamping was found to be a risk factor for postoperative death.

Adult↗
PubMed2006

External validation of the Prostate Cancer Prevention Trial risk calculator in a screened population.

OBJECTIVES: To evaluate the recently developed Prostate Cancer Prevention Trial (PCPT) prostate cancer risk calculator in the San Antonio Center of Biomarkers of Risk for Prostate Cancer (SABOR) cohort of the Early Detection Research Network, a younger and more ethnically diverse population than that in the PCPT. METHODS: From 3488 SABOR participants, we identified 446 who had undergone prostate biopsy and had undergone prostate-specific antigen measurement and digital rectal examination before biopsy. Most biopsies were performed for abnormal digital rectal examination findings, a prostate-specific antigen level of more than 2.5 ng/mL, or elevated risk because of a first-degree relative with prostate cancer. We evaluated the operating characteristics of the PCPT calculator for detecting prostate cancer in this cohort of SABOR participants. Of the 446 men in this cohort, 24% were younger than 55 years of age. RESULTS: Of the 446 men who had undergone biopsy, 148 (33.2%) had prostate cancer. The observed SABOR prostate cancer rates increased with increasing PCPT risk: 15.7%, 39.0%, 48.8%, and 100.0% for a PCPT risk calculator value of less than 25%, 25% to 50%, 50% to 75%, and greater than 75%, respectively. The PCPT risk calculator had an area under the receiver operating characteristic curve of 65.5% (95% confidence interval 60.2% to 70.8%, P < 0.0001), was greater in African-American men (area under curve of 80.0%, 95% confidence interval 67.8% to 92.2%) than in other races (P = 0.02), and was not different in Hispanic men (P > 0.05). CONCLUSIONS: The results of our study have shown that the PCPT risk calculator, available from the Internet and incorporating the current best panel of risk factors, is valid in other, more diverse, populations.

Aged↗
PubMed2000

Classifying environmental pollutants: Part 3. External validation of the classification system.

In order to validate a classification system for the prediction of the toxic effect concentrations of organic environmental pollutants to fish, all available fish acute toxicity data were retrieved from the ECETOC database, a database of quality-evaluated aquatic toxicity measurements created and maintained by the European Centre for the Ecotoxicology and Toxicology of Chemicals. The individual chemicals for which these data were available were classified according to the rulebase under consideration and predictions of effect concentrations or ranges of possible effect concentrations were generated. These predictions were compared to the actual toxicity data retrieved from the database. The results of this comparison show that generally, the classification system provides adequate predictions of either the aquatic toxicity (class 1) or the possible range of toxicity (other classes) of organic compounds. A slight underestimation of effect concentrations occurs for some highly water soluble, reactive chemicals with low log K(ow) values. On the other end of the scale, some compounds that are classified as belonging to a relatively toxic class appear to belong to the so-called baseline toxicity compounds. For some of these, additional classification rules are proposed. Furthermore, some groups of compounds cannot be classified, although they should be amenable to predictions. For these compounds additional research as to class membership and associated prediction rules is proposed.

Animals↗
PubMed2000

External validity of conduct and oppositional defiant disorders determined by the NIMH Diagnostic Interview Schedule for children.

We administered the Diagnostic Interview Schedule for Children (DISC) two times to a group of youth (222 boys, 147 girls) entering residential care, once at their time of entry and once 1 year later. We then compared their DISC outcomes on Conduct Disorder (CD) and Oppositional Defiant Disorder (ODD) against changes in independent direct observations of diagnostically relevant behavior obtained over the course of that year. Results from hierarchical linear modeling analyses showed significant discriminative relationships between results from the DISC and the independent observations. Specifically, observations of symptomatic behaviors (CD or ODD) decreased for youth who met diagnostic criteria at the first administration of the DISC but not at the second, increased for youth who did not meet criteria at the first administration but did at the second, and did not change for youth who met criteria at both administrations. These results extend the data on the validity of the DISC and support continued research efforts to determine its clinical utility.

Adolescent↗
PubMed1992

Covert antisocial behavior in boys with attention-deficit hyperactivity disorder: external validation and effects of methylphenidate.

Covert antisocial behaviors such as stealing, destroying property, and cheating carry high risk for delinquency. An individual laboratory setting was devised in which youngsters could take desired objects and use answer keys to assist with worksheets. Twenty-two boys with attention-deficit hyperactivity disorder (ADHD) and 22 comparison boys were observed on two occasions, with the ADHD Ss receiving a methylphenidate-placebo crossover. Laboratory stealing and property destruction were positively correlated with maternal and staff ratings of parallel behaviors. Methylphenidate resulted in significant reductions of these acts, but it also effected an increase in cheating, presumably because of its enhancement of task involvement. The generalizability of the laboratory findings, actions of stimulants in this domain, and the ethics of experimental investigations of covert antisocial behavior are discussed.

Antisocial Personality Disorder↗